4l4e

Publication Abstract from PubMed

A close homolog to the cytochrome P450cam that catalyzes the same hydroxylation of camphor to 5-exo hydroxycamphor is CYP101D1. There are potentially important differences in and around the active site that could contribute to subtle functional differences. Adjacent to the heme iron ligand, Cys357, is Leu358 in P450cam while this residue is Ala in CYP101D1. Leu358 plays a role in binding of the P40cam redox partner, putidaredoxin (Pdx). On the opposite side of the heme about 15 - 20 A away Asp251 in P450cam plays a critical role in a proton relay network required for O2 activation but forms strong ion pairs with Arg186 and Lys178. In CYP101D1 a Gly replaces Lys178. Thus, the local electrostatic environment and ion pairing is substantially different in CYP101D1. These sites have been systematically mutated in P450cam to the corresponding residues in CYP101D1 and the mutants analyzed by crystallography, kinetics, and UV/Vis spectroscopy. Individually the mutants have little effect on activity or structure but in combination there is a major drop in enzyme activity. This loss in activity is due the mutants being locked in the low-spin state which prevents electron transfer from the P450cam redox partner, Pdx. These studies illustrate the strong synergistic effects on well separated parts of the structure in controlling the equilibrium between the open (low-spin) and closed (high-spin) conformational states.

Synergistic Effects of Mutations in Cytochrome P450cam Designed to Mimic CYP101D1.,Batabyal D, Li H, Poulos TL Biochemistry. 2013 Jul 18. PMID:23865948^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.