Effect of temperature on the adenylate cyclase activity of Mytilus galloprovincialis mantle tissue.
1. The basal and NaF-stimulated adenylate cyclase activities of Mytilus galloprovincialis mantle tissue were studied at different temperatures. 2. There are no significant differences in the Km for ATP at 13 degrees C and 20 degrees C in both basal and NaF-stimulated conditions. 3. NaF increases the Vmax of the enzyme (5-fold) and decreases about 50% the Km for ATP at both temperatures assayed. 4. Activation energy of the enzyme reaction is 33.4 kJ/mol. K in basal conditions and 29.4 kJ/mol. K when NaF is present. The Q10, at saturating substrate concentrations, is approximately 1.5 and this value is constant in the temperature range studied, 10-30 degrees C. 5. The adenylate cyclase starts being inactivated from 30 degrees C. The enzyme shows greater sensitivity to denaturalization by temperature in NaF-stimulated than in basal conditions.
Mancebo
M J
MJ
Department of Physiology, Faculty of Pharmacy, University of Santiago de Compostela, Spain.
Treviño
M
M
Espinosa
J
J
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D049872:Bivalvia / Q000201:enzymology*; D005260:Female; D007700:Kinetics; D012969:Sodium Fluoride / Q000494:pharmacology; D013816:Thermodynamics
D012969:Sodium Fluoride; D000262:Adenylyl Cyclases