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. 1991 Nov 1;88(21):9463–9467. doi: 10.1073/pnas.88.21.9463

Subunit interactions change the heme active-site geometry in p-cresol methylhydroxylase.

G L McLendon 1, S Bagby 1, J A Charman 1, P C Driscoll 1, W S McIntire 1, F S Mathews 1, H A Hill 1
PMCID: PMC52738  PMID: 1946360

Abstract

The enzyme p-cresol methylhydroxylase [4-cresol: (acceptor) oxidoreductase (methyl-hydroxylating), EC 1.17.99.1] contains two subunits: a cytochrome c (electron transfer) subunit (cytochrome cpc) and a flavin (catalytic) subunit. When these subunits are separated by isoelectric focusing, a stable cytochrome subunit is obtained. Significant differences are observed between the one-dimensional NMR spectra of oxidized cytochrome cpc and of oxidized p-cresol methylhydroxylase. Analysis of the two-dimensional nuclear Overhauser enhancement and exchange spectroscopy (NOESY) spectrum of reduced cytochrome cpc suggests that the axial ligand, Met-50, of the stable subunit reorients by a rotation about the C gamma-S delta bond when cytochrome cpc binds to the flavin subunit. This reorientation must result in a change in bonding at the heme, which is reflected both in the para-magnetically shifted resonances and in the redox potential. p-Cresol methylhydroxylase thereby provides an interesting example of the coupling of subunit interactions to active-site structure and reactivity.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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