Sucrose Inversion by Bakers' Yeast as a Function

where k is the rate of the reaction, z is a constant, e is 2.718, R is the gas constant, T is the absolute temperature, and # represents the energy of activation in calories per tool of the pacemaker reaction in the catenary series of events controlling the rate (Crozier and Hoagland, 1934). Since most biological reactions are catalyzed by enzymes, the change in rate is determined by the enzyme, just as in chemical systems the temperature characteristic is indicative of the specific catalyst employed in the reaction. For certain isolated enzyme systems the data on rate of reaction as a function of temperature fit the Arrhenius equation. For yeast invertase, using different experimental conditions and measuring rate of inversion in a variety of ways,/z was found to be independent of temperature and has the value of 11,000-11,500 (Sizer, 1937, 1938). Crozier reported (1924) a cons tant /z = 16,700 obtained by analyzing Quastel's data on succinic dehydrogenase of E. coli. Craig (1936) isolated a fat oxidation system from Lupinus albus and obtained a/z = 11,700, when the system was saturated with oil, but the situation was more complicated if oil were not added. Certain other enzyme systems yield constant temperature characteristics at least over narrow ranges of temperature (Barnes, 1937).