title: Cyclic nucleotide phosphodiesterase in Dictyostelium discoideum: interconversion of two enzyme forms.
abstract: 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.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D000242:Cyclic AMP / Q000378:metabolism*; D004229:Dithiothreitol; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D009235:Myxomycetes / Q000201:enzymology* / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D013053:Spectrophotometry
chemical_list: D007527:Isoenzymes; D000242:Cyclic AMP; D010744:Phosphoric Monoester Hydrolases; D004229:Dithiothreitol