Purification and characterisation of a protein kinase from winged bean.
A soluble, cytoplasmic protein kinase was purified from the developing seeds of winged bean (Psophocarpus tetragonolobus) following conventional methods of protein purification including anion-exchange chromatography, gel-filtration and Blue Sepharose chromatography. The purified enzyme consists of a single polypeptide of M(r) 45,000 as determined by SDS-PAGE and gel-filtration chromatography on Sephacryl S-200. The pH optimum of the protein kinase activity was 7.0, while the optimum concentration of Mg2+ was 5 mM. The enzyme utilised casein as an exogenous phosphate acceptor. The conventional modulators of protein kinases, including the cyclic nucleotides, Ca2+ and calmodulin, did not stimulate the purified enzyme. Heparin and spermine, too, had no effect on its activity. Phosphoamino acid analysis revealed that the enzyme transferred the gamma-phosphate of ATP only to serine residues of casein. All these characteristics, taken together, classifies the purified protein kinase as a member of the casein kinase I group of enzymes.
Mukhopadhyay
K
K
Indian Institute of Chemical Biology, Calcutta, India.
D000596:Amino Acids / Q000032:analysis; D002147:Calmodulin / Q000494:pharmacology; D002364:Caseins / Q000737:chemistry / Q000378:metabolism; D002412:Cations; D002846:Chromatography, Affinity; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D007887:Fabaceae / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D010946:Plants, Medicinal; D011494:Protein Kinases / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000494:pharmacology
D000596:Amino Acids; D002147:Calmodulin; D002364:Caseins; D002412:Cations; D013438:Sulfhydryl Compounds; D000242:Cyclic AMP; D011494:Protein Kinases; D006152:Cyclic GMP