A COMPARISON OF THE MEMBRANE-BOUND AND EXTRACELLULAR CYCLIC-AMP PHOSPHODIESTERASES OF DICTYOSTELIUM-DISCOIDEUM
A COMPARISON OF THE MEMBRANE-BOUND AND EXTRACELLULAR CYCLIC-AMP PHOSPHODIESTERASES OF DICTYOSTELIUM-DISCOIDEUM
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DOI：
10.1016/0304-4165(83)90009-0
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
KESSIN, RH
中科院分区：
文献类型：
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作者：
SHAPIRO, RI;FRANKE, J;KESSIN, RH
D. discoideum 膜结合和细胞外环核苷酸磷酸二酯酶 (EC 3.1.4.17) 具有多种特性，包括与特定糖蛋白抑制剂和小抑制分子反应的能力。膜结合酶被部分纯化，并将其特性与胞外形式的特性进行比较。两种形式的动力学性质相似，不同之处在于，虽然与膜颗粒相关，但膜结合形式在广泛的底物范围内进行测定时表现出非线性动力学。当在 6 M 尿素存在下进行等电聚焦时，膜结合磷酸二酯酶的等电点与胞外酶的等电点相同。通过凝胶过滤测定的膜结合酶和胞外酶的分子量在 6 M 尿素存在下等电聚焦后相同。当用针对纯化的胞外磷酸二酯酶制备的抗血清进行沉淀时，部分纯化的膜结合酶制剂含有在SDS[十二烷基硫酸钠]聚丙烯酰胺凝胶电泳期间与胞外酶共迁移的MW 50,000的多肽。当对碘化胞外酶和来自膜结合酶的碘化MW 50,000多肽进行部分蛋白水解消化时，获得相似的谱，表明广泛的同源性区域。
The D. discoideum membrane-bound and extracellular cyclic nucleotide phosphodiesterases (EC 3.1.4.17) share several properties including the ability to react with a specific glycoprotein inhibitor and small inhibitory molecules. The membrane-bound enzyme was partially purified and its properties were compared to those of the extracellular form. The kinetic properties of the 2 forms were similar except that, while associated with membrane particles, the membrane-bound form exhibited non-linear kinetics when assayed over a broad substrate range. The isoelectric point of the membrane-bound phosphodiesterase was identical to that of the extracellular enzyme when isoelectrofocusing was done in the presence of 6 M urea. The MW of membrane-bound and extracellular enzyme, determined by gel filtration, were the same following isoelectrofocusing in the presence of 6 M urea. When precipitated with an antiserum prepared against purified extracellular phosphodiesterase, the partially purified membrane-bound enzyme preparation contained a MW 50,000 polypeptide comigrating with the extracellular enzyme during SDS [sodium dodecyl sulfate] polyacrylamide gel electrophoresis. When the iodinated extracellular enzyme and the iodinated MW 50,000 polypeptide from membrane-bound enzyme were subjected to partial proteolytic digestion, similar profiles were obtained indicating extensive regions of homology.