Subunit Interactions Change the Heme Active-Site Geometry in p-Cresol Methylhydroxylase
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 cyt...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 88; no. 21; pp. 9463 - 9467 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Washington, DC
National Academy of Sciences of the United States of America
01.11.1991
National Acad Sciences |
Subjects | |
Online Access | Get full text |
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Summary: | 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 cpcand of oxidized p-cresol methylhydroxylase. Analysis of the two-dimensional nuclear Overhauser enhancement and exchange spectroscopy (NOESY) spectrum of reduced cytochrome cpcsuggests that the axial ligand, Met-50, of the stable subunit reorients by a rotation about the Cγ-Sδ bond when cytochrome cpcbinds to the flavin subunit. This reorientation must result in a change in bonding at the heme, which is reflected both in the paramagnetically 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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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.88.21.9463 |