  4.99.1.9 | more |
active site architecture of wild-type and R45L mutant coproporphyrin ferrochelatases with bound physiological substrate coproporphyrin III, crystal structure analysis, propionate interactions and porphyrin core deformation, detailed overview. A cleft, build by structural elements of both ferredoxin-like domains, contains several conserved amino acid residues (distal H182 and E263, proximal Y12) and is the porphyrin binding site, where catalysis happens. The monomeric enzyme exhibits two ferredoxin-like domains, each with a four-stranded parallel beta-sheet flanked by alpha-helices. In cpIII-LmCpfC, as well as in the coproheme-bound structure, the porphyrin is oriented in the active site with the propionates 2 and 4 (p2 and p4) pointing to the inner core of the protein, p6 and p7 face towards the protein surface and are much more solvent exposed. In both cpIII and coproheme complexes with LmCpfC the H-bond interactions between the four propionates and six amino acids, Thr14, Arg29, Arg45, Tyr46, Ser53, and Tyr124, are fundamental to the porphyrin stabilization |
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