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  • 标题:Subunit interactions change the heme active-site geometry in p-cresol methylhydroxylase.
  • 本地全文:下载
  • 作者:G L McLendon ; S Bagby ; J A Charman
  • 期刊名称:Proceedings of the National Academy of Sciences
  • 印刷版ISSN:0027-8424
  • 电子版ISSN:1091-6490
  • 出版年度:1991
  • 卷号:88
  • 期号:21
  • 页码:9463-9467
  • DOI:10.1073/pnas.88.21.9463
  • 语种:English
  • 出版社:The National Academy of Sciences of the United States of America
  • 摘要: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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