Structure of Type A Catalases

Detailed structural information about Type A catalases is available 

Within this common core structure, modifications have been identified that provide catalases with further unique properties. The large-subunit enzymes have extensions at both the amino and carboxyl ends, the latter having a flavodoxinlike structure, a unique His-Tyr bond, a protected cysteine, and a modified heme. NADPH binding and an oxidized methionine are found in small subunit enzymes. Identification and assignment of roles to channels providing access to and egress from the deeply buried heme have recently become the focus of study. Analysis of the structure of catalase HPII of E. coli has been facilitated by the construction of more than 75 mutants (Table I). 

Mutation Specific activity (units/mg) Heme His392-Tyr415  

Presence of the His392-T3rr415 (y, yes n, no) covalent bond was determined by MALDI-MS analysis of trypic digest mixtures. Where no indication is given, no determination was made. 

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