Cyclic Nucleotide Phosphodiesterase in Dictyostelium discoideum: Interconversion of Two Enzyme Forms

Science  03 Mar 1972:
Vol. 175, Issue 4025, pp. 1016-1018
DOI: 10.1126/science.175.4025.1016


An extracellular cyclic nucleotide phosphodiesterase was isolated from either growing cultures or aggregating amoebas of Dictyostelium discoideum. The enzyme is released in a form with a low Michaelis constant (15 micromolar) and spontaneously undergoes a slow conversion to a less active form with a high Michaelis constant (2 mnillimolar). Inactivation was prevented or reversed by use of Cleland's reagent, dithiothreitol. The two enzyme forms may be part of a mechanism for control of concentration of cyclic adenosine monophosphate.