Tryptophan 121 of subunit II is the electron entry site to cytochrome-c oxidase in Paracoccus denitrificans. Involvement of a hydrophobic patch in the docking reaction

  • To investigate the contribution of hydrophobic residues to the molecular recognition of cytochrome c with cytochrome oxidase, we mutated several hydrophobic amino acids exposed on subunit II of the Paracoccus denitrificans oxidase. KM and kcat values and the bimolecular rate constant were determined under steady- or presteady-state conditions, respectively. We present evidence that Trp-121 which is surrounded by a hydrophobic patch is the electron entry site to oxidase. Mutations in this cluster do not affect the binding of cytochrome c as the KM remains largely unchanged. Rather, the kcat is reduced, proposing that these hydrophobic residues are required for a fine tuning of the redox partners in the initial collisional complex to obtain a configuration optimal for electron transfer.

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Author:Heike Witt, Francesco MalatestaORCiD, Flavia Nicoletti, Maurizio BrunoriORCiDGND, Bernd LudwigGND
Pubmed Id:
Parent Title (English):Journal of biological chemistry
Publisher:American Society for Biochemistry and Molecular Biology Publications
Place of publication:Bethesda, Md
Document Type:Article
Date of Publication (online):2021/01/04
Year of first Publication:1998
Publishing Institution:Universit├Ątsbibliothek Johann Christian Senckenberg
Release Date:2023/11/16
Page Number:5
First Page:5132
Last Page:5136
Institutes:Biochemie, Chemie und Pharmazie / Biochemie und Chemie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 4.0 International