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A positive charge route for the access of nadh to heme formed in the distal heme pocket of cytochrome p450nor
Arg and Lys residues are concentrated on the distal side of cytochrome P450nor (P450nor) to form a positively charged cluster facing from the outside to the inside of the distal heme pocket. We constructed mutant proteins in which the Arg and Lys residues were replaced with Glu, Gln, or Ala. The results showed that this cluster plays crucial roles in NADH interaction. We also showed that some anions such as bromide (Br(-)) perturbed the heme environment along with the reduction step in P450nor-catalyzed reactions, which was similar to the effects caused by the mutations. We determined by x-ray crystallography that a Br(-), termed an anion hole, occupies a key region neighboring heme, which is the terminus of the positively charged cluster and the terminus of the hydrogen bond network that acts as a proton delivery system. A comparison of the predicted mechanisms between the perturbations caused by Br(-) and the mutations suggested that Arg(174) and Arg(64) play a crucial role in binding NADH to the protein. These results indicated that the positively charged cluster is the unique structure of P450nor that responds to direct interaction with NADH.
A positively charged cluster formed in the heme-distal pocket of cytochrome P450nor is essential for interaction with NADH., Kudo T, Takaya N, Park SY, Shiro Y, Shoun H, J Biol Chem. 2001 Feb 16;276(7):5020-6. Epub 2000 Nov 13. PMID:11076941
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.