| Autor: |
Sligar, S G, Kennedy, K A, Pearson, D C |
| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; March 1980, Vol. 77 Issue: 3 p1240-1244, 5p |
| Abstrakt: |
Using isotopic tracer methods, we have shown that dihydrolipoic acid (2,3-thioctic acid) acylates the distal oxygen of ferrous oxygenated Pseudomonas cytochrome P-450, forming a transient acyl peroxide intermediate that facilitates oxygen-oxygen bond cleavage. Single-turnover studies with 18O2 indicate one oxygen-18 atom incorporated into the carboxylate group of lipoic acid for each oxygen-18 inserted into the substrate, camphor, forming the product, exo-5-hydroxycamphor. Such a branching ratio for label indicates that water is initially released from an unlageled position and illustrates that the general P-450 mixed-function oxidase stoichiometry generates H218O from 18O2 only after multiple-turnover equilibration with the acylating carboxylate oxygen. Formation of an acyl peroxide state is a natural intermediate in peracid, "oxene", or radical mechanisms for methylene carbone oxygenation. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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