Holocytochrome-c synthase
In enzymology, a holocytochrome-c synthase () is an enzyme that catalyzes the chemical reaction Hence, this enzyme has one substrate, holocytochrome c, and two products, apocytochrome c and heme. This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is holocytochrome-c apocytochrome-c-lyase (heme-forming). Other names in common use include cytochrome c heme-lyase, holocytochrome c synthetase, and holocytochrome-c apocytochrome-c-lyase. This enzyme participates in porphyrin and chlorophyll metabolism. Cytochrome c haem-lyase (CCHL) and cytochrome Cc1 haem-lyase (CC1HL ) are mitochondrial enzymes that catalyse the covalent attachment of a haem group on two cysteine residues of cytochrome c and c1. These two enzymes are functionally and evolutionary related. There are two conserved regions, the first is located in the central section and the second in the C-terminal section. Both patterns contain conserved histidine, tryptophan and acidic residues which could be important for the interaction of the enzymes with the apoproteins and/or the haem group. The human enzyme, HCCS, processes both cytochromes "c" and "c1".