Characterization of a nitrite-reducing octaheme hydroxylamine oxidoreductase that lacks the tyrosine cross-link.

ABSTRACT: The hydroxylamine oxidoreductase (HAO) family consists of octaheme proteins that harbor seven bis-His ligated electron-transferring hemes and one 5-coordinate catalytic heme with His axial ligation. Oxidative HAOs have a homotrimeric configuration with the monomers covalently attached to each other via a unique double cross-link between a Tyr residue and the catalytic heme moiety of an adjacent subunit. This cross-linked active site heme, termed the P460 cofactor, has been hypothesized to modulate enzyme reactivity toward oxidative catalysis. Conversely, the absence of this cross-link is predicted to favor reductive catalysis. However, this prediction has not been directly tested. In this study, an HAO homolog that lacks the heme-Tyr cross-link (HAOr) was purified to homogeneity from the n

SUBMITTER: Ferousi C 

PROVIDER: S-EPMC8042395 | biostudies-literature | 2021 Jan-Jun

REPOSITORIES: biostudies-literature