Adenyl Cyclase of Rat Cerebral Cortex

It was concluded that adenyl cyclase exists in its membranous environment in a state of inhibition and treatment with detergents or freezing of the tissue could lead to nonspecific changes in membrane structure which cause reduction of the inhibition and increased catalytic activity.

Abstract

Sodium fluoride activates adenyl cyclase at a rate that is dependent on temperature and the concentration of NaF.The activation is not readily reversed by dilution, extensive washing of the membrane-bound enzyme, or dialysis.Activation occurs in the absence of added Mg++, but the rate of activation is increased Z-fold by 5 mM Mg++.The NaFactivated enzyme is more stable at 40" and during dialysis than the native enzyme.The enzyme also is activated by Triton X-100 and to a lesser extent by sodium dodecyl sulfate.The activity of the detergent-treated enzyme is not stimulated by NaF, but the activity of the NaF-activated enzyme can be increased by Triton X-100.Thus, NaF does not cause full expression of adenyl cyclase activity.Freezing and thawing of the cerebral cortex of young (1 to 20 days) rats prior to homogenization causes a 2-fold increase in enzyme activity.It was concluded that adenyl cyclase exists in its membranous environment in a state of inhibition.Treatment with detergents or freezing of the tissue could lead to nonspecific changes in membrane structure which cause reduction of the inhibition and increased catalytic activity.