Subunit interactions change the heme active-site geometry in p-cresol methylhydroxylase.
AUTOR(ES)
McLendon, G L
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=52738Documentos Relacionados
- p-cresol methylhydroxylase from a denitrifying bacterium involved in anaerobic degradation of p-cresol.
- Anaerobic oxidation of p-cresol mediated by a partially purified methylhydroxylase from a denitrifying bacterium.
- Structure of an intermolecular electron-transfer complex: p-cresol methylhydroxylase at 6.0-A resolution.
- Metabolism of p-Cresol by the Fungus Aspergillus fumigatus
- Pathways for the degradation of m-cresol and p-cresol by Pseudomonas putida.
