Identification of a histidine-tyrosine cross-link in the active site of the cbb3-type cytochrome c oxidase from Rhodobacter sphaeroides.

ABSTRACT: The heme-copper oxidases constitute a superfamily of terminal dioxygen-reducing enzymes located in the inner mitochondrial or in the bacterial cell membrane. The presence of a mechanistically important covalent bond between a histidine ligand of the copper ion (Cu(B)) in the active site and a generally conserved tyrosine residue nearby has been shown to exist in the canonical cytochrome c oxidases. However, according to sequence alignment studies, this critical tyrosine is missing from the subfamily of cbb(3)-type oxidases found in certain bacteria. Recently, homology modeling has suggested that a tyrosine residue located in a different helix might fulfill this role in these enzymes. Here, we show directly by methods of protein chemistry and mass spectrometry that there is indeed a covalen

SUBMITTER: Rauhamaki V 

PROVIDER: S-EPMC1637549 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature