Abstract
In human platelet lysates, metal and metal-ATP interactions with adenylate cyclase have been studied, using Mg++ as divalent cation. The kinetic pattern followed Michaelis-Menten kinetics and conformed to a bireactant mechanism in which free metal served as a requisite activator. The alpha adrenergic component of epinephrine (20 µM) reduced Vmax of the enzyme by about 60% without changing the apparent affinities for the substrate, Mg-ATP, and the activator, free Mg++. The inhibition was partial and noncompetitive, with an apparent KI value of 2 µM for epinephrine.
ACKNOWLEDGMENTS We are grateful to Ms. Gabriele Gabel for superb technical assistance and to Dr. Roger A. Johnson for his helpful advice during the kinetic experiments.
- Copyright © 1978 by Academic Press, Inc.
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