| Sumario: | Particulate cell fractions of mycelium of Mucor rouxii contain adenylate cyclase activity which can be partially solubilized by 0.5 m KCl. Homogenates prepared in the presence of Lubrol PX or KCl exhibit two- to threefold more activity compared to homogenates prepared in the absence of detergent or salt. The membrane-bound enzyme prepared in the presence of 2% Lubrol PX was studied in detail. The kinetic properties of this adenylate cyclase were as expected for an allosteric enzyme with the ATP · Mn2- complex as substrate and free Mn2+ ions as activator. Unchelated ATP inhibits the reaction by competing with the substrate. The KCl-solubilized enzyme was partially purified by ion-exchange chromatography, ammonium sulfate precipitation, and gel filtration. Molecular parameters of the solubilized enzyme are: Stokes radius, 8.6 nm; S20,w, 13S; Mr 510,000; and frictional ratio, 1.60. © 1982.
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