| Abstract: | Using ion-exchange chromatography and gel filtration, cGMP-dependent protein kinase was purified from prawn tissues 220-fold with a yield of activity of 12%. The apparent Ka values for cGMP, cAMP and 8-Br-cGMP are 1 . 10(-7), 5 . 10(-6) and 5 . 10(-8) M, respectively; the apparent Km values for ATP in the presence of cGMP is 9 . 10(-6) M. The cGMP-stimulated protein kinase activity was observed only in the presence of SH-compounds and high Mg2+ concentrations (500-100 mM). The protein kinase demonstrated a broad pH optimum wih a maximum at pH 6.8-7.2. The elution volume of the enzyme during gel filtration corresponded to a globular protein with molecular weight of 140,000. |
