[The effect of substrates on stability of firefly luciferase, embedded in phosphatidylcholine liposomes]

The effects of substrates (ATP and luciferin) on stability of firefly luciferase embedded into phosphatidylcholine liposomes have been studied. Luciferin did not exert any appreciable influence on enzyme inactivation. Minor concentrations of adenosine 5'-triphosphate destabilized the enzyme; however, the increase in ATP concentration markedly stabilized the enzyme entrapped into liposomes. A kinetic scheme of ATP action on enzyme inactivation is proposed. According to this scheme, the enzyme has two ATP-binding sites.