Publications
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Citations >7,700, h index = 43 (Web of Science) 2018 180. P. C. Loewen, J. Switala, J. P. Wells, F, Huang, A. T. Zara, J. S. Allingham and M. C. Loewen. 2018. Structure and function of a lignostilbene-alpha,beta-dioxygenase orthologue from Pseudomonas brassicacearum. BMC Biochemistry 19: 8. doi.org/10.1186/s12858-018-0098-4. View PDF 179. P. C. Loewen, P. M. De Silva, L. J. Donald, J. Switala, J. Villaneuva, I. Fita and A. Kumar. 2018. KatG-mediated oxidation imparts reduced susceptibility to kanamycin. ACS Omega 3: 4213-4219. View PDF 178. A. Ivancich and P. C. Loewen. 2018. Electron transfer in catalases and catalase-peroxidases. In Robert, G. and Watts, A., European Biophysical Societies (eds), Encyclopedia of Biophysics, Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-35943-9_51-1. View PDF 2017 177. D. Vila-Vicosa, B, Victor, J. Ramos, D. machado, M. Viveiros, J. Switala, P. C. Loewen, R. Leitao, F. Martins and M. Machuqueiro. 2017. Insights on the mechanism of action of INH-C10 as an anti-tubercular pro-drug. Molec. Pharm. 14: 4597-4605. View PDF 176. M. Machuquerio, B. Victor, J. Switala, J. Villanueva, C. Rovira, I. Fita and P. C. Loewen. 2017. Catalase activity of catalase-peroxidases is modulated by changes in pKa of the distal histidine. Biochemistry 56: 2271-2281. View PDF 175. D. M. Fernando, P. Chong, M. Singh, V. Spicer, M. Unger, P. C. Loewen, G. Westmacott, and A. Kumar. 2017. Multi-omics approach to study global changes in a triclosan-resistant mutant strain of Acinetobacter baumannii ATCC 17978. Int. J. Antimicrob. Agts. 49: 74-80. View PDF 2016 174. M. Nandi, C. Berry, A. K. C. Brassinga, M. F. Belmonte, W. G. D. Fernando, P. C. Loewen and T. R. de Kievit. 2016. Pseudomonas brassicacearum strain DF41 kills Caenorhaditis elegans through biofilm-dependent and biofilm-independent mechanisms. Appl. Environ. Micro. 82: 6889-6898. View PDF 173. J. Wiens, R. Ho, D. Fernando, A. Kumar, P. C. Loewen, A. K. Brassinga and W. G. Anderson. 2016. Complete genome sequence of the Rhodococcus species isolated from the winter skate Leucoraja ocellata. genomeA 4: e00918-16 View PDF 172. W. Behrens, T. Schweinitzer, J. McMurry, P. C. Loewen, F. Buttner, S. Menz and C. Josenhans. 2016. Localisation and protein-protein interactions of the Helicobacter pylori taxis sensor TlpD and their connection to metabolic functions. Scientific Reports 6: 23582, doi:10.1038/srep23582 View PDF 171. D. Sun, S. A. Crowell, C. M. Harding, P. M. DeSilva, A. Harrison, D. M. Fernando, K. M. Mason, E. Santana, P. C. Loewen, A. Kumar and Y. Liu. 2016. KatG and KatE confer Acinetobacter resistance to hydrogen peroxide but sensitize bacteria to killing by phagocytic respiratory burst. Life Sciences 148: 31-40. View PDF 2015 170. M. M. Galka, N. Rajagopalan, L. M. Buhrow, K. M. Nelson, J. Switala, A. J. Cutler, D. R. J. Palmer, P. C. Loewen, S. R. Abrams and M. C. Loewen. (2015) Identification of interactions between abscisic acid and ribulose-1,5-bisphosphate carboxylase/oxygenase. PLoS One 10(7):e0133033 doi:10.1371/journal/pone.0133033 View PDF 169. I. Fita, X. Carpena and P. C. Loewen. (2015) Catalase-peroxidase (KatG) structure and function. Heme peroxidases. ed. E. Raven and B. Dunford 168. M. Nandi, C. Selin, A. K. C. Brassinga, M. F. Belmonte, W. G. D. Fernando, P. C. Loewen and T. R. de Kievit. (2015) Pyrrolnitrin and hydrogen cyanide production by Pseudomonas chlororaphis strain PA23 exhibits potent nematicidal and repellent activity against Caenorhabditis elegans. PLoS One 10(4):e0123184 doi:10.1371/journal.pone.0123184 View PDF 167. I. Fita, P. C. Loewen and X. Carpena. (2015) Catalase-peroxidase:KatG. Encyclopedia of Inorganic and Bioinorganic Chemistry ed. R. A. Scott, John Wiley: Chichester. DOI: 10.1002/9781119951438.eibc2273 View PDF 166. P. C. Loewen, J. Villanueva, J. Switala, L. J. Donald and A. Ivancich. (2015) Unprecedented access of phenolic substrates to the heme active site of a catalase: substrate binding and peroxidase-like reactivity of Bacillus pumilus catalase monitored by X-ray crystallography and EPR spectroscopy. Proteins 83: 853-866. View PDF 2014 165. P. C. Loewen, Y. Alsaadi, D. Fernando and A. Kumar. (2014) Genome sequence of Acinetobacter baumannii AB031, a tigecycline-resistant clinical isolate from bloodstream infection. genomeA 2: e01036-14 View PDF 164. P. C. Loewen, Y. Alsaadi, D. Fernando and A. Kumar. (2014) Genome sequence of Acinetobacter baumannii AB030, an extreme drug-resistant (XDR) clinical isolate. genomeA 2: e01035-14 View PDF 163. D. Fernando, W. Xu, P. C. Loewen, G. G. Zhanel and A. Kumar. (2014) Triclosan can select for an AdeIJK overexpressing mutant of Acinetobacter baumannii ATCC17978 that displays reduced susceptibility to multiple antibiotics. Antimicrob. Agents Chemo. 58: 6424-6431. View PDF 162. P. C Loewen, J. Villanueva, W. G. D. Fernando and T. de Kievit. (2014) Genome sequence of Pseudomonas chlororaphis PA23. genomeA 2: e00689-14 View PDF 161. K. D. Miner, T. D. Pfister, P. Hosseinzadeh, N. Karaduman, L. J. Donald, P. C. Loewen, Y. Lu and A. Ivancich. (2014) Identifying the elusive sites of tyrosyl radicals in cytochrome c peroxidase: implications for oxidation of substrates bound at a site remote from the heme. Biochemistry 53: 3781-3789 View PDF 160. P. C. Loewen, X. Carpena, P. Vidossich, I. Fita and C. Rovira. (2014) An ionizable active site tryptophan imparts catalase activity to a peroxidase core. J. Am. Chem. Soc. 136: 7249-7252. View PDF 159. P. C. Loewen, J. Switala, D. Fernando and T. de Kievit. (2014) Genome sequence of Pseudomonas brassicacearum DF41. 2014. genomeA 2: e00390-24. View PDF 158. J. Villanueva, J. Switala, A. Ivancich and P. C. Loewen. (2014) Genome sequence of Bacillus pumilus MTCC B6033. genomeA 2: e00327-14. View PDF 157. P. Vidossich, P. C. Loewen, X. Carpena, G. Fiorin, I. Fita, and C. Rovira. (2014) Binding of the anti-tubercular pro-drug isoniazid in the heme access channel of catalase-peroxidase (KatG). A combined structural and metadynamics investigation. J. Phys. Chem. B 118: 2924-2931. View PDF 156. M. M. S. Ismaiel, Y. M. El-Ayouty, P. C. Loewen, M. D. Piercey-Normore. (2014) Characterization of the iron-containing superoxide dismutase and its response to stress in cyanobacterium Spirulina (Arthrospira) platensis. J. Appl. Phycology DOI 10.1007/s10811-013-0233-y. View PDF 155. C. L. Berry, M. Nandi, J. Manuel, A. K. C. Brassinga, W. G. D. Fernando, P. C. Loewen and T. R. de Kievit. (2014) Characterization of the Pseudomonas sp. DF41 quorum sensing locus and its role in fungal antagonism. Biol. Control 69: 82-89. View PDF 2013 154. A. Ivancich, L. J. Donald, J. Villanueva, B. Wiseman, I. Fita, and P. C. Loewen. (2013) Spectroscopic and kinetic investigation of the reactions of peroxyacetic acid with Burkholderia pseudomallei catalase-peroxidase, KatG. Biochemistry 52: 7271-7282. View PDF 153. D. Aparicio, R. Perez-Luque, X. Carpena, M. Diaz, J. C. Ferrer, P. C. Loewen and I. Fita. (2013) Structural asymmetry and disulphide bridges amoung subunits modulate the activity of human malonyl-CoA decarboxylase. J. Biol. Chem. 288: 11907-11919. View PDF 152. P. C. Loewen, A. L. Didychuk, J. Switala, R. Perez-Luque, I. Fita and M. C. Loewen. (2013) Structure of Pisum sativum rubisco with bound ribulose-1,5-bisphosphate. Acta. Crystallog. F69: 10-14. View PDF 2012 151. D. A. Alarcon, M. Nandi, X. Carpena, I. Fita and P. C. Loewen. (2012) Structure of glycerol-3-phosphate dehydrogenase, GPD1, from Saccharomyces cerevisiae at 2.45 Å resolution. Acta. Crystallog. F68 :1279-1283. View PDF 150. M. Zamocky, Q. Garcia-Fernández, B. Gasselhuber, C. Jakopitsch, P. G. Furtmüller, P. C. Loewen, I. Fita, C. Obinger and X. Carpena. (2012) High conformation stability of secreted eukaryotic catalase-peroxidases – answers from the first crystal and unfolding studies. J. Biol. Chem. 287: 32254-32262. View PDF 149. V. Jha, P. Chelikani, X. Carpena, I. Fita and P. C. Loewen. (2012) Influence of main channel structure on H2O2 access to the heme cavity of catalase KatE of Escherichia coli. Arch. Biochem. Biophys. 526: 54-59. View PDF 148. C. L. Berry, A. K. C. Brassinga, L. J. Donald, W.G. D. Fernando, P. C. Loewen, and T. R. de Kievit. (2012) Investigation of the structure and biological activity of a novel lipopeptide essential for Pseudomonas sp. DF41 biocontrol of Sclerotinia sclerotiorum. Can. J. Microbiol. 58: 1027-1034. View PDF 147. A. Diaz, P. C. Loewen, I. Fita and X. Carpena. (2012) Thirty years of heme catalase structural biology. Arch. Biochem. Biophys 525: 102-110 View PDF 146. V. Jha, L. J. Donald and P. C. Loewen. (2012) Mutation of Phe413 to Tyr in catalase KatE from Escherichia coli leads to side chain damage and main chain cleavage. Arch. Biochem. Biophys 525: 207-214 (2012). View PDF 145. A. Ivancich and P. C. Loewen. (2012) Electron transfer in catalases and catalase-peroxidases. In Encyclopedia of Biophysics. ed. G. C. K. Roberts Springer-Verlag, Vol. 2, pp 611-614. 144. M. Hafez, M. Iranpour, S.-T. Mullineux, J. Sethuraman, K. Wosnitza, P. Lehn, J. Kroeker, P. C. Loewen, J. Reid, and G. Hausner. (2012) Group I intron-like elements within the SSU rDNA gene in species of Ceratocystiopsis and related taxa. Fungal Biol. 116:98-111. View PDF 2011 143. V. Jha, S. Louis, P. Chelikani, X. Carpena, L. J. Donald, I. Fita and P. C. Loewen. (2011) Modulation of heme orientation and binding by a single residue in catalase HPII of E. coli. Biochemistry 50: 2101-2110. View PDF 142. P. Vidossich, X. Carpena, P. C. Loewen, I. Fita and C. Rovira. (2011) Oxygen binding to catalase-peroxidase. J. Phys. Chem. Let. 2: 196-200. View PDF 2010 141. J. Reid, M. Iranpour, S. M. Rudski, P. C. Loewen and G. Hausner. (2010) A new conifer-inhabiting species of Ceratocystis from Norway. Botany 88: 971-983. View PDF 140. C. Berry, W. G. D. Fernando, P. C. Loewen, and T. R. de Kievit. (2010) Lipopeptides are essential for Pseudomonas sp. DF41 biocontrol of Sclerotinia sclerotiorum. Biological Control 55: 211-218. View PDF 139. B. Wiseman, X. Carpena, M. Feliz, L. J. Donald, M. Pons, I. Fita and P. C. Loewen. (2010) Isonicotinic acid hydrazide (INH) conversion to isonicotinyl-NAD by catalase-peroxidases. J. Biol. Chem. 285: 26662-26673. View PDF 138. P. Vidossich, M. Alfonso-Prieto, X. Carpena, I. Fita, P. C. Loewen and C. Rovira (2010) The dynamic role of distal side residues in heme hydroperoxidase catalysis. Interplay between X-ray crystallography and ab initio MD simulations. Arch. Biochem. Biophys. 500: 37-44. View PDF 2009 137. J. Colin, B. Wiseman, J. Switala, P. C. Loewen and A. Ivancich. (2009) Distinct role of specific tryptophans in facilitating electron transfer or as [Fe(IV)=O Trpo] intermediates in the peroxidase reaction of Burkholderia pseudomallei catalase-peroxidase: a multifrequency EPR spectroscopy investigation. J. Am. Chem. Soc. 131:8557-8563 View PDF 136. B. Wiseman, J. Colin, A. T. Smith, A. Ivancich and P. C. Loewen. (2009) Mechanistic insight into the initiation step of the reaction of Burkholderia pseudomallei catalatse-peroxidase with peroxyacetic acid. J. Biol. Inorg. Chem. 14: 801-811 View PDF 135. L. J. Donald, V. M. Collado, J. J. Galka, J. D. O’Neil, H. W. Duckworth, P. C. Loewen and K. G. Standing. (2009) Urea as a protein destabilizing agent in electrospray ionization. Rapid Commun. in Mass Spectrom. 23: 788-792 View PDF 2008 134. M. Alfonso-Prieto, P. Vidossich, A. Rodríguez-Fortea, X. Carpena, I. Fita, P. C. Loewen and Carme Rovira. (2008) Electronic state of the molecular oxygen released in the catalase reaction. J. Phys. Chem. A 112: 12842-12848. View PDF 133. A. J. Fielding, R. Singh, B. Boscolo, P. C. Loewen, E. M. Ghibaudi, and A. Ivancich. (2008) Intramolecular electron transfer vs. substrate oxidation in lactoperoxidase: investigation of the radical intermediates by stopped-flow absorption spectrophotometry and (9-285 GHz) EPR spectroscopy. Biochemistry 47: 9781-9792 View PDF 132. R. Singh, B. Wiseman, T. Deemagarn, V. Jha, J. Switala and P. C. Loewen. (2008) Comparative study of catalase-peroxidases (KatGs). Arch. Biochem. Biophys. 471: 207-214. View PDF 131. J. Richardson, X. Carpena, J. Switala, P. C. Loewen and I Oresnik. (2008) RhaU of Rhizobium leguminosarum is a rhamnose mutarotase. J. Bacteriol. 190: 2903-2910. View PDF 130. G. Hausner, J. Reid, G. G. Eyjolfsdottir, M. Iranpour and P. C. Loewen (2008) Basidiopycnides albertensis gen. et spec. nov., a new anamporphic fungus whith phylogenetic affinities in the Atractiellales (Basidiomycota). Mycotaxon. 103: 279-297. View PDF 129. R. Singh, J. Switala, P. C. Loewen and A. Ivancich. (2007) Two [Fe(IV)=O Trp·] intermediates in M. tuberculosis catalase-peroxidase discriminated by multifrequency (9-285 GHz) EPR spectroscopy: reactivity towards isoniazid. J. Am. Chem. Soc. 129: 15954-15963. View PDF 128. P. Vidossich, M. Alfonso-Prieto, X. Carpena, P. C. Loewen, I. Fita and C. Rovera. (2007) Versatility of the electronic structure of compound I in catalase-peroxidases (KatGs). J. Am. Chem. Soc. 129: 13426-13446. View PDF 127. G. R. Golding, C. A. Kelly, R. Sparling, P. C. Loewen, and T. Barclay (2007) Evaluation of mercury toxicity as a predictor of mercury bioavailability. Environ. Sci. Tech41: 5685-5692. View PDF 126. M. Alfonso-Prieto, A. Borovik, X. Carpena, G. Murshudov, W. Melik-Adamyan, I. Fita, C. Rovira and P. C. Loewen. 2007. The structures and electronic configuration of compound I intermediates of Helicobacter pylori and Penicillium vitale catalases determined by X-Ray crystallography and QM/MM DFT calculations. J. Am. Chem. Soc.> 129: 4193-4205. View PDF 125. C. Jakopitsch, J. Vlasits, B. Wiseman, P. C. Loewen and C. Obinger. (2007) Redox intermediates in the catalase cycle of catalase-peroxidases from Synechocystis PCC 6803, Burkholderia pseudomallei, and Mycobacterium tuberculosis. Biochemistry 46: 1183-1193. View PDF 124. T. Deemagarn, B. Wiseman, X. Carpena, A. Ivancich, I. Fita and P. C. Loewen (2007) Two alternative substrate paths for compound I formation and reduction in catalase-peroxidase KatG from Burkholderia pseudomallei. Proteins 66: 219-228. View PDF 123. X. Carpena, B. Wiseman, T. Deemagarn, B. Herguedas, A. Ivancich, R. Singh, P. C. Loewen, and I. Fita. (2006) Roles for Arg426 and Trp111 in the modulation of NADH oxidase activity of the catalase-peroxidase KatG from Burkholderia pseudomallei inferred from pH-induced structural changes. Biochemistry 45: 5171-5179. View PDF 122. C. Rovira, M. Alfonso, X. Biarnés, X. Carpena, I. Fita, and P. C. Loewen. (2006) A first principles study of the binding of formic acid in catalase complementing high resolution X-ray structures. Chem. Phys. 323: 129-137. View PDF 121. M. Miller-Williams, P. C. Loewen and I. J. Oresnik. (2006) Isolation of salt sensitive mutants of Sinorhizobium meliloti strain Rm1021 Microbiology 152: 2049-2059. View PDF 120. K. Choudhary, V. L. Spicer, L. J. Donald, H. W. Duckworth, W. Ens, P. C. Loewen, and K. G. Standing. (2006) A method for estimating the isotopic distributions of metabolically labeled proteins by MALDI-TOFMS: application to NMR samples. Anal. Chem. 78: 5419-5423. View PDF 119. R. Habibian, J. Dzioba, J. Barrett, M. Y. Galperin, P. C. Loewen and P. Dibrov. (2005). Functional analysis of conserved polar residues in VcNhaD, Na+/H+ antiporter of Vibrio cholerae. J. Biol. Chem. 280: 39637-39643. View PDF 118. X. Carpena, B. Wiseman, T. Deemagarn, R. Singh, J. Switala, A. Ivancich, I. Fita and P.C. Loewen (2005) A molecular switch and electronic circuit modulate activity in catalase-peroxidases. EMBO Reports 6: 1156-1162. View PDF 117. G. Hausner, M. Iranpour, J.-J. Kim, C. Breuil, C, N. Davis, E. A. Gibb, J. Reid, J., P. C. Loewen, and A. A. Hopkin. (2005). Fungi vectored by the introduced bark beetle Tomicus piniperda in Ontario, Canada and comments on the taxonomy of Leptographium lundbergii, L. terebrantis, L. truncatum and L. wingfieldii. Can. J. Bot. 83: 1222-1237. View PDF 116. P.Chelikani, X. Carpena, R. Perez-Luque, L. J. Donald, H. W. Duckworth, J. Switala, I. Fita and P. C. Loewen. (2005) Characterization of a large subunit catalase truncated by proteolytic cleavage. Biochemistry 44: 5597-5605. View PDF 115. T. Deemagarn, X. Carpena, R. Singh, B. Wiseman, I. Fita and P. C. Loewen. (2005) Structural characterization of the Ser324Thr variant of the catalase-peroxidase (KatG) from Burkholderia pseudomallei. J. Mol. Biol. 345: 21-28. View PDF 114. X. Carpena, W. Melik-Adamyan, P. C. Loewen, and I. Fita. 2004. Crystal structure of the C-terminal domain from the catalase-peroxidase KatG of Escherichia coli. Acta Cryst. D60: 1824-1832. View PDF 113. S. H. Cho, P. C. Loewen, and R. R. Marquardt 2004. A plasmid DNA encoding chicken Interleukin-6 and Escherichia coli K88 fimbrial protein FaeG stimulates the production of anti-K88 fimbrial antibodies in chickens Poultry Sci. 83: 1973-1978. View PDF 112. R. Singh, B. Wiseman, T. Deemagarn, L. J. Donald, H. W. Duckworth, X.Carpena, I. Fita, and P. C. Loewen 2004. Catalase-peroxidases (KatG) exhibit NADH oxidase activity. J. Biol. Chem. 279: 43098-43106. View PDF 111. P. C. Loewen, X. Carpena, R. Perez-Luque, C. Rovira, A. Ivancich, R. Perez-Luque, R. Haas, S. Odenbreit, P. Nicholls, and I. Fita. 2004. Structure of Helicobacter pylori catalase, with and without formic acid bound, at 1.6 Å resolution. Biochemistry 43: 3089-3103. View PDF 110. P. Chelikani, I. Fita and P. C. Loewen 2004. Diversity of structures and properties among catalases. Cell Molec. Life Sci. 61: 192-208. View PDF 109. L. J.Donald, O. V. Krokhin, H. W. Duckworth, B.Wiseman, T. Deemagarn, R.Singh, J. Switala, X. Carpena, I. Fita and P. C. Loewen (2003) Characterization of the catalase-peroxidase KatG from Burkholderia pseudomallei by mass spectrometry. J. Biol. Chem. 278: 35687-35692. View PDF 108. P. Chelikani, X. Carpena, I. Fita and P. C. Loewen 2003. An electrical potential in the access channel of catalases enhances catalysis. J. Biol. Chem.278: 31290-31296. View PDF 107. P. Chelikani, L. J. Donald, H. W. Duckworth and P. C. Loewen 2003. Hydroperoxidase II of Escherichia coli exhibits enhanced resistance to proteolytic cleavage compared to other catalases. Biochemistry 42: 5729-5735. View PDF 106. M. G. Klotz and P. C. Loewen (2003) The molecular evolution of catalatic hydroperoxidases: Evidence for multiple lateral transfer of genes between prokaryota and from bacteria into eukaryota. Molec. Biol. Evol. 20: 1098-1112. View PDF 105. X. Carpena, S. Loprasert, S. Mongkolsuk, J. Switala, P. C. Loewen and I. Fita. 2003. Catalase-peroxidase KatG of Burkholderia pseudomallei at 1.7 Å resolution. J. Mol. Biol. 327: 475-489. View PDF 104. X. Carpena, M. Soriano, M. G. Klotz, H. W. Duckworth, L. J. Donald, I. Fita and P. C. Loewen. 2003. Structure of the clade 1 catalase, CatF from Pseudomonas syringae at 1.7 Å resolution. Proteins50: 423-436. View PDF 103. N. Chauvatcharin, P. Vattanaviboon, J. Switala, P. C. Loewen, and S. Mongkolsuk 2003. Cloning and characterization of katA, encoding the major monofunctional catalase from Xanthomonas campestris pv. phaseoli and characterization of the encoded catalase KatA. Curr. Microbiol. 46: 83-87. View PDF 102. X. Carpena, J. Switala, S. Loprasert, S. Mongkolsuk, I. Fita and P. C. Loewen. 2002. Crystallization and preliminary X-ray analysis of the catalase-peroxidase KatG from Burkholderia pseudomallei. Acta Cryst.D58: 2184-2186. View PDF 101. E. Ostroumov, J. Dzioba, P. C. Loewen and P. Dibrov 2002. Asp344 and Thr345 are critical for cation exchange mediated by NhaD, Na+/H+ antiporter of Vibrio cholerae. Biochim. Biophys. Acta. 1564: 99-106. View PDF 100. G. R. Golding, C. A. Kelly, R.Sparling, P. C. Loewen, J. W. M. Rudd, and T. Barkay. 2002. Evidence for facilitated uptake of Hg(II) by Vibrio anguillarum and Escherichia coli under anaerobic and aerobic conditions. Limnol. Oceanog.47: 967-975. View PDF 99. J. Switala and P. C. Loewen. 2002 Diversity of properties among catalases. Arch. Biochem. Biophys. 401:145-154. View PDF 98. X. Carpena, A. Guarné, J. C. Ferrer, P. M. Alzari, I. Fita, and P. C. Loewen. 2002 Crystallization and preliminary X-ray analysis of the hydroperoxidase I C-terminal domain from Eschericia coli. Acta Cryst.D58: 853-855. View PDF 97. X. Carpena, R. Perez, W. F. Ochoa, N. Verdaguer, M. Klotz, J. Switala, W. Melik-Adamyan, I. Fita, and P. C. Loewen. 2001. Crystallisation and preliminary X-ray analysis of Clade I catalases from Pseudomonas syringae and Listeria seeligeri. Acta Cryst. D57: 1184-1186. View PDF 96. G. Regelsberger, C. Jakopitsch, F. Rüker, J. Switala, P. C. Loewen, and C. Obinger. 2001. The role of distal tryptophan in the bifunctional activity of catalase-peroxidases. Biochem. Soc. Trans. 29: 99-105. View PDF 95. W. Melik-Adamyan, J. Bravo, X. Carpena, J. Switala, M. J. Maté, I. Fita and P. C. Loewen. 2001. Substrate flow in catalases deduced from the crystal structures of active site variants of HPII from Escherichia coli. Proteins 44: 270-281. View PDF 94. L. Powers, A. Hillar and P. C. Loewen. 2001. Active site structure of the catalase-peroxidases from Mycobacterium tuberculosis and Escherichia coli by extended X-ray absorption fine structure analysis (EXAFS) Biochim. Biophys. Acta 1546: 44-54. View PDF 93. P. Nicholls, I. Fita and P. C. Loewen. 2001. Enzymology and structure of catalases. Adv. Inorg. Chem. 51: 51-106. View PDF 92. M. J. Mate, G. Murshudov, J. Bravo, W. Melik-Adamyan, P. C. Loewen and I. Fita. 2001. Heme catalases. In: Handbook of Metalloproteins pp 486-502, J. Wiley & Sons, New York, NY View PDF 91. P. C. Loewen, M. G. Klotz, and D. J. Hassett. 2000. Catalase – an ‘old’ enzyme that continues to surprise us. ASM News 66: 76-82. View PDF 90. A. Hillar, B. Peters, R. Pauls, A. Loboda, H. Zhang, A. G. Mauk, and P. C. Loewen. 2000. Modulation of the activities of catalase-peroxidase HPI of Escherichia coli by site-directed mutagenesis. Biochemistry 39: 5868-5875. View PDF 89. M. J. Mate, M. S. Sevinc, B. Hu, J. Bujons, J. Bravo, J. Switala, W. Ens, P. C. Loewen, and I. Fita. 1999. Mutants that alter the covalent structure of catalase HPII from Escherichia coli. J. Biol. Chem. 274: 27717-27725. View PDF 88. P. C. Loewen.1999. Catalase. In: The Encyclopedia of Molecular Biology ed. T. Creighton, pp 351-353, J. Wiley & Sons, New York, NY View PDF 87. J. Switala, J. O’Neil, and P. C. Loewen. 1999. Catalase HPII from Escherichia coli exhibits enhanced resistance to denaturation. Biochemistry 38: 3895-3901. View PDF 86. A. Hillar, L. Van Caeseele and P. C. Loewen. 1999. Intracellular location of catalase-peroxidase HPI of E. coli. FEMS Microbiol. Lett. 170: 307-312. View PDF 85. M. S. Sevinc, M. J. Mate, J. Switala, I. Fita, and P. C. Loewen. 1999. Role of the lateral channel in catalase HPII of Escherichia coli. Protein Sci. 8: 490-498. View PDF 84. J. Bravo, M. J. Mate, T. Schneider, J. Switala, K. Wilson, P. C. Loewen, and I. Fita. 1999. Structure of catalase HPII from Escherichia coli at 1.9 Å resolution. Proteins 34: 155-166. View PDF 83. P. C. Loewen, B. Hu, J. Strutinsky and R. Sparling. 1998. Regulation in the rpoS regulon of Escherichia coli. Can. J. Microbiol. 44: 707-717. View PDF 82. M. S. Sevinc, J. Switala, J. Bravo, I. Fita, and P.C. Loewen. 1998. Truncation and heme pocket mutations reduce the accumulation of functional catalase HPII of Escherichia coli. Prot. Eng. 11: 549-555. View PDF 81. M. Maj, P. C. Loewen and P. Nicholls. 1998. E. coli HPII catalase interaction with high spin ligands: formate and fluoride as active site probes. Biochim. Biophys. Acta 1384: 209-222. View PDF 80. K. Tanaka, K. Handel, P. C. Loewen and H. Takahashi. 1997. Identification and analysis of the RpoS-dependent promoter of katE, encoding catalase HPII in Escherichia coli. Biochim. Biophys. Acta 1352: 161-166. View PDF 79. C. Obinger, M. Maj, P. Nicholls and P. C. Loewen. 1997. Activity, peroxide compound formation and heme d synthesis in E. coli HPII catalase. Arch. Biochem. Biophys. 342: 58-67. View PDF 78. J. Bravo, I. Fita, J. C. Ferrer, W. Ens, A. Hillar, J. Switala and P. C. Loewen. 1997. Identification of a novel bond between a histidine and the essential tyrosine in catalase HPII of Escherichia coli. Protein Science 6: 1016-1023. View PDF 77. M. G. Klotz, G. R. Klassen and P. C. Loewen. 1997. Phylogenetic relationaships among prokaryotic and eukaryotic catalases. Molec. Biol. Evol. 14: 951-958. View PDF 76. P. C. Loewen 1997. Bacterial catalases. In: Oxidative Stress and the Molecular Biology of Antioxidant Defenses. pp.273-308. Cold Spring Harbor Laboratory Press, Cold Spring Harbor NY View PDF 75. M. Maj, P. Nicholls, C. Obinger, A. Hillar and P.C. Loewen. 1996. Reaction of E. coli catalase HPII with cyanide as ligand and as inhibitor. Biochim. Biophys. Acta1298: 241-249. View PDF 74. P. C. Loewen. 1996. Probing the structure of HPII of Escherichia coli – a review. Gene 179: 39-44. View PDF 73. G. N. Murshudov, A. I. Grebenko, V. Barynin, Z. Dauter, K. S. Wilson, B. K. Vainshtein, W. Melik-Adamyan, J. Bravo, J. M. Ferran, J. C. Ferrer, J. Switala, P. C. Loewen, and I. Fita. 1996. Structure of heme d of Penicillium vitale and Escherichia coli catalases. J. Biol. Chem. 271: 8863-8868. View PDF 72. P. C. Loewen and J. Switala. 1995. Template structure can increase the error frequency of the DNA polymerase from Thermus aquaticus. Gene 164: 59-63. View PDF 71. A. Hillar and P. C. Loewen. 1995. Comparison of isoniazid oxidation catalyzed by bacterial catalase-peroxidases and horse radish peroxidase. Arch. Biochem. Biophys. 323: 438-446. View PDF 70. M. S. Sevinc, W. Enns and P. C. Loewen. 1995. The cysteines of catalase HPII of Escherichia coli, including Cys438 which is blocked, do not have a catalytic role. Eur. J. Biochem. 230: 127-132. View PDF 69. J. Bravo, N. Verdaguer, J. Tormo, C. Betzel, J. Switala, P. C. Loewen and I. Fita 1995. Crystal structure of catalase HPII from Escherichia coli. Structure 3: 491-502. View PDF 68. N. A. Buchmeier, S. J. Libby, Y. Xu, P. C. Loewen, J. Switala, D. G. Guiney and F. C. Fang. 1995. DNA repair is more important than catalase for Salmonella virulence in mice. J. Clin. Invest. 95: 1047-1053. View PDF 67. P. C. Loewen and R. Hengge-Aronis. 1994. The role of the sigma factor sigma-S (KatF) in bacterial global regulation. Annu. Rev. Microbiol. 48: 53-80. View PDF 66. A. Hillar, P. Nicholls, J. Switala and P. C. Loewen. 1994. NADPH binding and control of catalase compound II formation: comparison of bovine, yeast and Escherichia coli enzymes. Biochem. J. 300: 531-539. View PDF 65. F. F. Davidson, P. C. Loewen and H. G. Khorana. 1994. Structure and function in rhodopsin: replacement by alanine of cysteine residues 110 and 187, components of a conserved disulfide bond in rhodopsin, affects the light-activated metarhodopsin II state. Proc. Natl. Acad. Sci USA 91: 4029-4033. View PDF 64. M. R. Volkert, P. C. Loewen, J. Switala, D. Crowley and M. Conley. 1994. The delta(argF-lacZ)205(U169) deletion greatly enhances resistance to hydrogen peroxide in stationary-phase Escherichia coli. J. Bacteriol.176: 1297-1302. View PDF 63. P. C. Loewen, J. Switala, I. von Ossowski, A. Hillar, A. Christie, B. Tattrie and P. Nicholls. 1993. Catalase HPII of Escherichia coli catalyzes the conversion of protoheme to cis-heme d. Biochemistry 32: 10159-10164. View PDF 62. I. von Ossowski, G. Hausner, and P.C. Loewen. 1993. Molecular evolutionary analysis based on the amino acid sequence of catalase. J. Mol. Evol.37: 71-76. View PDF 61. P.C. Loewen, I. von Ossowski, J. Switala and M.R. Mulvey. 1993. KatF (sigma-S) synthesis in Escherichia coli is subject to post-transcriptional regulation. J. Bacteriol.> 175: 2150-2153. View PDF 60. F.C. Fang, S.J. Libby, N.A. Buchmeier, P.C. Loewen, J. Switala, J. Harwood, and D.G. Gurney. 1992. The alternative sigma factor KatF regulates Salmonella virulence. Proc. Natl. Acad. Sci. USA 89: 11978-11982. View PDF 59. Q. Pang, R. Timkovich, P.C. Loewen and J. Peterson. 1992. Identification of heme macrocycle type by near-infrared magnetic circular dichroism spectroscopy at cryogenic temperatures. FEBS Lett. 309: 157-160. View PDF 58. P.C. Loewen. 1992. Regulation of bacterial catalase synthesis. In: Molecular Biology of Free Radical Scavenging Systems>. pp. 77-115. Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. View PDF 57. J.H. Dawson, A.M. Bacete, A.M. Huff, S. Kadkhodayan, C.M. Zeitter, M. Sono, C.K. Chang and P.C. Loewen. 1991. The active site structure of E. coli HPII catalase. Evidence favoring coordination of a tyrosinate proximal legand to the chlorin iron. FEBS Lett.> 295: 123-126. View PDF 56. I. von Ossowski, M.R. Mulvey, P.A. Leco, A. Borys and P.C. Loewen 1991. Nucleotide sequence of katE of Escherichia coli encoding catalase HPII. J. Bacteriol. 173: 514-520. View PDF 55. M.R. Mulvey, J. Switala, A. Borys and P.C. Loewen 1990. Regulation of transcription of katE and katF in Escherichia coli. J. Bacteriol. 172: 6713-6720. View PDF 54. P.C. Loewen and G.V. Stauffer. 1990. Nucleotide sequence of katG of Salmonella typhimurium LT2 and characterization of its product, hydroperoxidase I. Molec. Gen. Genet. 224: 147-151. View PDF 53. J. Switala, B.L. Triggs-Raine and P.C. Loewen 1990. Homology among bacterial catalase genes. >Canad. J. Microbiol. 36: 728-731. View PDF 52. P.C. Loewen, J. Switala, M. Smolenski and B.L. Triggs-Raine 1990. Molecular characterization of three mutations in katG, affecting the activity of hydroperoxidase I of Escherichia coli. Biochem. Cell Biol. 68: 1037-1044. View PDF 51. J. Tormo, I. Fita, J. Switala and P.C. Loewen 1990. Crystallization and preliminary x-ray diffraction analysis of catalase HPII from Escherichia coli. J. Mol. Biol. 213: 219-220. View PDF 50. M.R. Mulvey and P.C. Loewen. 1989. Nucleotide sequence of katF suggests KatF protein is a novel sigma transcription factor. Nucl. Acids Res.> 17: 9979-9991. View PDF 49. J.T. Chiu, P.C. Loewen, J. Switala, R.B. Gennis & R. Timkovich. 1989. Proposed structure for the prosthetic group of the catalase HPII from Escherichia coli. J. Am. Chem. Soc. 111: 7046-7050. View PDF 48. P.C. Loewen. 1989. Genetic mapping of katB, a locus that affects catalase 2 levels in Bacillus subtilis. Can. J. Microbiol. 35: 807-810. View PDF 47. M.R. Mulvey, P.A. Sorby, B.L. Triggs-Raine and P.C. Loewen. 1988. Cloning and physical characterization of katE and katF, required for catalase HPII expression in E. coli. Gene 73: 337-345. View PDF 46. B.L. Triggs-Raine, B.W. Doble, M.R. Mulvey, P.A. Sorby and P.C. Loewen. 1988. Nucleotide sequence of katG encoding catalase HPI of Escherichia coli. J. Bacteriol. 170: 4415-4419. View PDF 45. P.C. Loewen and J. Switala. 1988. Purification and characterization of spore-specific catalase-2 from Bacillus subtilis. Biochem. Cell. Biol.66: 707-714. View PDF 44. H.E. Richter, J. Switala and P.C. Loewen 1988. Effect of ascorbate on oxygen uptake and growth of Escherichia coli B. >Can. J. Microbiol. 34: 822-824. View PDF 43. P.C. Loewen and J. Switala 1987. Genetic mapping of katA, a locus that affects the synthesis of catalase-1 in Bacillus subtilis. J. Bacteriol. 169: 5848-5851. View PDF 42. P.C. Loewen and J. Switala 1987. Purification of catalase-1 from Bacillus subtilis. Biochem. Cell Biol. 65: 939-947. View PDF 41. P.C. Loewen and J. Switala 1987. Multiple catalases in Bacillus subtilis. J. Bacteriol. 169: 3601-3607. View PDF 40. B.L. Triggs-Raine and P.C. Loewen 1987. Physical characterization of katG, encoding catalase HPI of Escherichia coli. Gene 52: 121-128. View PDF 1986 39. P.C. Loewen and J. Switala 1986. Purification and characterization of catalase HPII from Escherichia coli K12. Can. J. Biochem. Cell Biol. 64: 638-646. View PDF 38. P.C. Loewen, J. Switala and B.L. Triggs-Raine 1985. Catalases HPI and HPII in Escherichia coli are induced independently. Arch. Biochem. Biophys. 243: 144-149. View PDF 37. P.C. Loewen, B.L. Triggs, C.S. George and B.E. Hrabarchuk 1985. Genetic mapping of katG, a locus that affects the synthesis of the bifunctional catalase-peroxidase HPI in Escherichia coli. J. Bacteriol. 162: 661-667. View PDF 36. F.C. Wong, J.G. Spearman, M.A. Smolenski and P.C. Loewen 1985. Equine parvovirus: Initial isolation and partial characterization. Can. J. Comp. Med. 49: 50-54. View PDF 35. P.C. Loewen 1985. Detection of p-aminobenzoylpoly(gamma-glutamates) using fluorescamine. Methods in Enzymology 122: 330-333. View PDF 34. P.C. Loewen and B.L. Triggs 1984. Genetic mapping of katF, a locus that with katE affects the synthesis of a second catalase species in Escherichia coli. J. Bacteriol. 160: 668-675. View PDF 33. P.C. Loewen 1984. Isolation of catalase-deficient Escherichia coli mutants and genetic mapping of katE, a locus that affects catalase activity. J. Bacteriol. 157: 622-626. View PDF 32. P.C. Loewen, B.L. Triggs, G.R. Klassen and J.H. Weiner 1983. Identification and physical characterisation of a ColEl hybrid plasmid containing a catalase gene of Escherichia coli. Can. J. Biochem. 61: 1315-1321. View PDF 31. P.C. Loewen and H.E. Richter 1983. Inhibition of sugar uptake by ascorbic acid in Escherichia coli. Arch. Biochem. Biophys. 226: 657-665. View PDF 30. W.J.P. Blonski, F.E. Hruska, K.L. Sadana and P.C. Loewen 1983. Conformational studies of ribo-, 2′-deoxyribo- and arabinonucleotides by carbon 13 NMR. <Biopolymers 22: 605-616. View PDF 29. H.E. Richter and P.C. Loewen 1982. Rapid inactivation of bacteriophage T7 by ascorbic acid is repairable. Biochem. Biophys. Acta 697: 25-30. View PDF 28. H.E. Richter and P.C. Loewen 1982. Catalase synthesis in Escherichia coli is not controlled by catabolite repression. Arch. Biochem. Biophys.215: 72-77. View PDF 27. K.L. Sadana, F.E. Hruska and P.C. Loewen 1981. A simplified strategy for the synthesis of dideoxyribonucleotide blocks. Tetrahedron Letters< 22: 3367-3370. View PDF 26. R.A.H. Furness and P.C. Loewen 1981. Detection of p-aminobenzoyl(gamma- glutamates) using fluorescamine. Anal. Biochem. 117: 126-135. View PDF 25. H.E. Richter and P.C. Loewen 1981. Induction of catalase in Escherichia coli by ascorbic acid involves hydrogen peroxide. Biochem. Biophys. Res. Comm. 100: 1039-1046. View PDF 24. W.P. Niemczura, F.E. Hruska, K.L. Sadana and P.C. Loewen 1981. Proton magnetic resonance study of nucleosides, nucleotides and dideoxynucleoside monophosphates containing a syn pyrimidine base. Biopolymers 20: 1671-1690. View PDF 23. P.C. Loewen 1981. Effect of glutathione deficiency on the pool of CoA-glutathione mixed disulfide in Escherichia coli. Can. J. Biochem. 59: 379-382. View PDF 22. W.C.H. Bees and P.C. Loewen 1979. Partial characterization of the mode of inhibition of E. coli RNA polymerase by the mixed disulfide, CoASSG. Can. J. Biochem. 57: 336-345. View PDF 21. P.C. Loewen 1979. Levels of glutathione in E. coli. Can. J. Biochem. 57: 107-111. View PDF 20. K.L. Sadana and P.C. Loewen 1978. A rapid and efficient synthesis of ribonucleotides. Tetrahedron Letters 5095-5098. View PDF 19. P.C. Loewen 1978. Levels of coenzyme A-glutathione mixed disulfide in Escherichia coli. Can. J. Biochem. 56: 753-759. View PDF 18. D.R. McNaughton, G.R. Klassen, P.C. Loewen and H.B. LéJohn 1978. Recharacterization of fungal dinucleoside polyphosphate (HS3). Can. J. Biochem.56: 217-226. View PDF 17. J. Peeling, F.E. Hruska and P.C. Loewen 1978. Ribo-, 2′-deoxyribo- hybrid dinuclesoide monophosphates. Proton, magnetic resonance studies of 3′, 5′- and 2′,5′-uridylyl-2′-deoxythymidine. Can. J. Chem.> 56: 522-529. View PDF 16. P.C. Loewen l977. Identification of a coenzyme A-glutathione disulfide (DSI), a modified coenzyme A disulfide (DSII) and a NADPH-dependent coenzyme A-glutathione disulfide reductase in E. coli. Can. J. Biochem. 55: 1019-1027. View PDF 15. P.C. Loewen 1976. Partial characterization of an endonuclease activity which appears in nuclease free T4 polynucleotide kinase. Nucl. Acids Res. 3: 3133-3141. View PDF 14. G.R. Klassen, R.A. Furness and P.C. Loewen 1976. Inhibition of E. coli DNA dependent RNA polymerase by novel nucleotides DSI and DSII. Biochem. Biophys. Res. Comm. 72: 1056-1062. View PDF 13. P.C. Loewen 1976. Novel nucleotides from E. coli isolated and partially characterized. Biochem. Biophys. Res. Comm. 70: 1210-1218. View PDF 12. R. Kleppe, T. Sekiya, P.C. Loewen, K. Kleppe, A.L. Agarwal, H. Buchi, P. Besmer, M.H. Caruthers, P.J. Cashion, M. Fridkin, E. Jay, A. Kumar, R.C. Miller, K. Minamoto, A. Panet, U.L. RajBhandary, B. Ramamoorthy, N. Siderova, T. Takeya, J.H. van de Sande and H.G. Khorana 1976. Studies on Polynucleotides CXLI. Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from E. coli. Enzymatic joining to form the total DNA duplex. J. Biol. Chem. 251: 667-675. View PDF 11. P.C. Loewen, R.C. Miller, A. Panet, T. Sekiya and H.G. Khorana 1976.Studies on polynucleotides CXXXVIII. Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from E. coli. Enzymatic joining of the chemically synthesized segments to form DNA duplexes corresponding to the nucleotide sequences 23 to 60 and 23 to 66. J. Biol. Chem. 251: 642-650. View PDF 10. H.G. Khorana, K.L. Agarwal, P. Besmer, H. Buchi, M.H. Caruthers, P.J. Cashion, M. Fridkin, E. Jay, K. Kleppe, R. Kleppe, A. Kumar, P.C. Loewen, R.C. Miller, K. Minamoto, A. Panet, U.L. RajBhandary, B. Ramamoorthy, T. Sekiya, T. Takeya and J.H. van de Sande 1976. Studies on Polynucleotides CXXXI. Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer from E. coli. General introduction. J. Biol. Chem. 251: 565-570. View PDF 9. P.C. Loewen 1974. Determination of the sequences of 18 nucleotides from the 5′-end of the 1-strand and 15 nucleotides from the 5′-end of the r-strand of T7 DNA. Nucleic Acids Research 2: 839-852. View PDF 8. P.C. Loewen, T. Sekiya and H.G. Khorana 1974. Studies on Polynucleotides CXXVI. The nucleotide sequence adjoining the CCA end of the E. coli tyrosine transfer RNA gene. >J. Biol. Chem. 249: 217-226. View PDF 7. P.C. Loewen and H.G. Khorana 1973. Studies on Polynucleotides CXXII. Dodecanucleotide sequence adjoining the CCA end of the tyrosine transfer RNA gene. J. Biol. Chem. 248: 3489-3499. View PDF 6. A. Panet, J.H. van de Sande, P.C. Loewen, H.G. Khorana, A.J. Raae, J.L. Lillehaug and K. Kleppe 1973. Studies on Polynucleotides CXXIII. Physical characterisation and simultaneous purification of bacteriophage T4 induced polynucleotide kinase, polynucleotide ligase and DNA polymerase. Biochemistry 12: 5045-5050. View PDF 5. H. van de Sande, P.C. Loewen and H.G. Khorana 1972. Studies on Polynucleotides CXVIII. A further study of ribonucleotide incorporation into DNA by DNA polymerase I of E. coli. J. Biol. Chem. 247: 6140-6148. View PDF 4. P.C. Loewen and R.K. Brown 1972. 2-Aryloxytetrahydrofurans. Their reductive cleavage by ether solutions of AlH2Cl and their cleavage and rearrangement by ether solutions of AlCl3. Can. J. Chem. 50: 3639-3647. View PDF 3. P.C. Loewen, L.P. Makubu and R.K. Brown 1972. The influence of the 2-alkoxy group and C-5 substituents on the direction of reductive cleavage of 2-alkoxytetrahydrofurans by AlH2Cl in ether solution. Can. J. Chem. 50: 1502-1512. View PDF 2. P.C. Loewen, W.W. Zajac and R.K. Brown 1969. Hydrogenolysis of LiAlH4-AlCl3 of an ether solution of norcamphor isobutylene ketal. Can. J. Chem. 47: 4059-4067. View PDF 1. T.L. Richards and P.C. Loewen 1965. A preliminary investigation of solar radiation over the Great Lakes as compared to adjacent land areas. Proc. Eighth Conf. on Great Lakes Research 13: 278-282. View PDF |
 Tetrameric catalase HPII of E. coli   Monomer of HPII before (top) and after (bottom) treatment with proteinase K (protease resistant core in red).
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