Calcium-regulated photoproteins of marine coelenterates

Abstract

Ca(2+)-regulated photoproteins are bioluminescent proteins responsible for bioluminescence of marine coelenterates. The photoprotein molecule is a stable enzyme-substrate complex consisting of a single polypeptide chain and an oxygen "pre-activated" substrate, 2-hydroperoxycoelenterazine, which is tightly but non-covalently bound with a protein. The bioluminescence is triggered by calcium ions and originates from an oxidative decarboxylation of a protein bound substrate. The review provides current data on the photoproteins structure, the mechanism of bioluminescent reaction, the function of some amino acid residues of an active site in the catalysis and the formation of the emitter, as well as on applications of these proteins in a bioluminescent analysis.