Redox equilibria of manganese peroxidase from Phanerochaetes chrysosporium: Functional role of residues on the proximal side of the haem pocket

Roberta Santucci, Cristiana Bongiovanni, Stefano Marini, Rebecca Del Conte, Ming Tien, Lucia Banci, Massimo Coletta

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Redox potentials of recombinant manganese peroxidase from Phanerochaeres chrysosporium have been measured by cyclic voltammetry as a function of pH, between pH 4.5 and pH 10.5. They display a bimodal behaviour (characterized by an 'alkaline' and an 'acid' transition), which indicates that (at least) two protonating groups change their pK(b) values upon reduction (and/or oxidation) of the iron atom in haem. Analogous measurements have been carried out on four site-directed mutants involving residues in close proximity to the proximal ligand, His173, in order to investigate the role played by residues of the proximal haem pocket on the redox properties of this enzyme. Results obtained suggest that the protonation state of N(δ) of the proximal imidazole group is redox-linked and that it is crucial in regulating the 'alkaline' transition. On the other hand, none of the proximal mutants alters the 'acid' transition, suggesting that it is modulated by groups located in a different portion of the protein.

Original languageEnglish (US)
Pages (from-to)85-90
Number of pages6
JournalBiochemical Journal
Volume349
Issue number1
DOIs
StatePublished - Jul 1 2000

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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