Effect of temperature on the kinetics of the yeast AMP deaminase

The temperature dependence of the kinetics of the yeast AMP deaminase was examined using the purified enzyme and the permeabilized yeast cells. The increase in the enzyme affinity for the substrate AMP was accompanied by the decrease in the maximal velocity with the decreasing temperature in the absence and presence of ATP. The apparent Km for AMP was lowest at 15-20 degrees C, and the affinity was decreased below and above this temperature. The rate of the AMP deaminase reaction remained constant over a wide range of temperature in the presence of physiological AMP concentrations. The temperature dependent change in kinetic properties of AMP deaminase may contribute to the control of the yeast glycolytic flux under the condition of lower temperature environments.