1CCG

CONSTRUCTION OF A BIS-AQUO HEME ENZYME AND REPLACEMENT WITH EXOGENOUS LIGAND

Summary for 1CCG

• Entry DOI: 10.2210/pdb1ccg/pdb
• Descriptor: CYTOCHROME C PEROXIDASE, PROTOPORPHYRIN IX CONTAINING FE, IMIDAZOLE, ... (4 entities in total)
• Functional Keywords: oxidoreductase(h2o2(a))
• Biological source: Saccharomyces cerevisiae (baker's yeast)
• Cellular location: Mitochondrion matrix: P00431
• Total number of polymer chains: 1
• Total formula weight: 33830.42

Authors

Mcree, D.E.,Jensen, G.M.,Fitzgerald, M.M.,Siegel, H.A.,Goodin, D.B. (deposition date: 1994-05-04, release date: 1994-07-31, Last modification date: 2024-02-07)

Primary citation

McRee, D.E.,Jensen, G.M.,Fitzgerald, M.M.,Siegel, H.A.,Goodin, D.B.
Construction of a bisaquo heme enzyme and binding by exogenous ligands.
Proc.Natl.Acad.Sci.USA, 91:12847-12851, 1994

PubMed Abstract: The crystal structure of the His-175-->Gly (H175G) mutant of cytochrome-c peroxidase (EC 1.11.1.5), missing its only heme ligand, reveals that the histidine is replaced by solvent to give a bisaquo heme protein. This protein retains some residual activity, which can be stimulated or inhibited by addition of exogenous ligands. Structural analysis confirms the binding of imidazole to the heme at the position of the wild-type histidine ligand. This imidazole complex reacts readily with hydrogen peroxide to produce a radical species with novel properties. However, reactivation in this complex is incomplete (approximately 5%), which, in view of the very similar structures of the wild-type and the H175G/imidazole forms, implies a critical role for tethering of the axial ligand in catalysis. This study demonstrates the feasibility of constructing heme enzymes with no covalent link to the protein and with unnatural ligand replacements. Such enzymes may prove useful in studies of electron transfer mechanisms and in the engineering of novel heme-based catalysts.

PubMed: 7809133
DOI: 10.1073/pnas.91.26.12847

Experimental method

X-RAY DIFFRACTION (2.1 Å)