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.
journal_name
Proc Natl Acad Sci U S Aauthors
McLendon GL,Bagby S,Charman JA,Driscoll PC,McIntire WS,Mathews FS,Hill HAdoi
10.1073/pnas.88.21.9463subject
Has Abstractpub_date
1991-11-01 00:00:00pages
9463-7issue
21eissn
0027-8424issn
1091-6490journal_volume
88pub_type
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