MODULATION BY SUBSTRATE, ADENOSINE 5'-TRI PHOSPHATE, LIPID-PROTEIN INTERACTIONS IN FIREFLY LUCIFERIN LUCIFERASE SYSTEM

The firefly luciferase was absorbed at the nitrocellulose membranes co ated by phosphatidylcholine at different concentrations of substrates: luciferin or ATP. The bioluminescence intensity of the adsorbed enzym e was measured. No influence of luciferin (0-50 muM) on the protein ad sorption was found. Whereas, with the growth of ATP concentration, at first the bioluminescence signal decreased two times, then increased t o the limit value which was 1,4 time higher than the signal in the cas e of the adsorption without ATP. That light change was explained by th e different quantities of the luciferase adsorbed on the membrane coat ed by phospholipid at different ATP concentrations. When the adsorptio n was carried out at the presence of albumin, no dependence of the lig ht signal on the ATP concentration was found. ATP didn't exert any eff ect on the protein adsorption at the membranes which were not coated b y phosphatidylcholine. According the hypothesis proposed, ATP can modu late the lipid-luciferase interactions and so change the affinity of t he enzyme to the phospholipid bilayer.