Studies on potato tuber phosphorylase-catalyzed reaction in the absence of an exogenous acceptor. I. Characterization and properties of the enzyme
Phosphorylase II from potato tuber has been subjected to several purification procedures in order to: (a) separate the unprimed activity from the primed one coexisting in the enzymatic preparation, and (b) eliminate endogenous glucan and/or glycoproteins. Large-scale analytical nondenaturing gel ele...
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| Autores principales: | , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00039861_v212_n2_p525_Sivak |
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| Sumario: | Phosphorylase II from potato tuber has been subjected to several purification procedures in order to: (a) separate the unprimed activity from the primed one coexisting in the enzymatic preparation, and (b) eliminate endogenous glucan and/or glycoproteins. Large-scale analytical nondenaturing gel electrophoresis and affinity chromatography on concanavalin A-Sepharose 4B succeeded in removing endogenous glycoproteins without any effect on the unprimed activity. In addition, phosphorolysis or glucoamylase treatment of the enzymatic preparation did not abolish the phosphorylase-catalyzed reaction in the absence of an exogenous acceptor. However, no separation between both activities, primed and unprimed, could be achieved either by the above-mentioned methods or by sucrose density gradient centrifugation. Based on sodium dodecyl sulfate-urea-gel electrophoresis, a molecular weight of about 96,000 was found for the phosphorylase II subunit. Molecular weight determination by nondenaturing gel electrophoresis at 5, 6, 7, and 8% acrylamide and by ultracentrifugation on sucrose density gradients suggested that the native enzyme is a dimer, as are other phosphorylases. © 1981. |
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