title: The temperature-dependence of adenylate cyclase from baker's yeast.
abstract: The Michaelis constant of membrane-bound adenylate cyclase increased from 1.1 to 1.8 mM between 7 and 38 degrees C (delta H = 13 kJ/mol). Over this temperature range, the maximum velocity increased 10-fold, and the Arrhenius plot was nearly linear, with an average delta H* of 51 kJ/mol. The temperature-dependence of the reaction rate at 2 mM-ATP was examined in more detail: for Lubrol-dispersed enzyme, Arrhenius plots were nearly linear with average delta H* values of 45 and 68 kJ/mol, respectively, for untreated and gel-filtered enzymes; for membrane-bound enzyme, delta H changed from 40 kJ/mol above about 21 degrees C to 62 kJ/mol below 21 degrees C, but this behaviour does not necessarily indicate an abrupt, lipid-induced, transition in the reaction mechanism.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D007700:Kinetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013696:Temperature
chemical_list: D000255:Adenosine Triphosphate; D000262:Adenylyl Cyclases