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.K M and k cat 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 K Mremains largely unchanged. Rather, the k cat 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.
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 / Witt, H; Malatesta, Francesco; Nicoletti, F; Brunori, Maurizio; Ludwig, B.. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 273:(1998), pp. 5132-5136. [10.1074/jbc.273.9.5132]
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.
MALATESTA, FRANCESCO;BRUNORI, Maurizio;
1998
Abstract
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.K M and k cat 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 K Mremains largely unchanged. Rather, the k cat 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.