The active site structure of E. coli HPII catalase : Evidence favoring coordination of a tyrosinate proximal ligand to the chlorin iron

• Published in: FEBS letters Vol. 295; no. 1; pp. 123 - 126
• Main Authors: Dawson, John H., Bracete, Alma M., Huff, Ann M., Kadkhodayan, Saloumeh, Zeitler, Caroline M., Sono, Masanori, Chang, Chi K., Loewen, Peter C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 16-12-1991; Elsevier
• Subjects: Active site structure determination; Analytical, structural and metabolic biochemistry; Binding Sites; Biological and medical sciences; Catalase; Catalase - chemistry; Catalase - metabolism; Circular Dichroism; Dihydroporphyrin; Electron Spin Resonance Spectroscopy; Enzymes and enzyme inhibitors; EPR spectroscopy; Escherichia coli - enzymology; Fundamental and applied biological sciences. Psychology; Isoenzymes - chemistry; Isoenzymes - metabolism; Magnetic circular dichroism spectroscopy; Oxidoreductases; Porphyrins; Protein Conformation; Tyrosinate proximal ligand; Tyrosine; Tyrosinate proximal ligand; Active site structure determination; Catalase; Magnetic circular dichroism spectroscopy; EPR; HRP; Dihydroporphyrin; MeC; OEC; EPR spectroscopy; MCD; Enzyme; Isozyme; Escherichia coli; Active site; EPR spectrometry; Bacteria; Magnetic circular dichroism; Enterobacteriaceae; Structural analysis
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(91)81401-S

E. coli produces 2 catalases known as HPI and HPII. While the heme prosthetic group of the HPII catalase has been established to be a dihydroporphyrin or chlorin, the identity of the proximal ligand to the iron has not been addressed. The magnetic circular dichroism (MCD) spectrum of native ferric HPII catalase is very similar to those of a 5-coordinate phenolate-ligated ferric chlorin complex, a model for tyrosinate proximal ligation, as well as of chlorin-reconstituted ferric horseradish peroxidase, a model for 5-coordinate histidine ligation. However, further MCD comparisons of chlorin-reconstituted myoglobin with parallel ligand-bound adducts of the catalase clearly rule out histidine ligation in the latter, leaving tyrosinate as the best candidate for the proximal ligand.