Sobrino F, Prieto J C, Ruiz G, Pintado E, Goberna R
Rev Esp Fisiol. 1978 Sep;34(3):285-9.
A cAMP-dependent protein kinase has been isolated from rabbit muscle and purified. The affinity constant of the enzyme for the nucleotide is Ka = 9.3 X 10(-9) M, with a Vmax = 0.013 X 10(12) moles bound cAMP/1 microgram protein. The influence exerted by different factors is studied: a) Inhibitor (I) of kinase activity: increases the binding capacity for cAMP, by percentages which depend on the amount of I. In the presence of inhibitor (120 microgram/100 microliter) the affinity constant is Ka = 4.1 X 10(-9) M, without change in Vmax. b) Effect of pH: it has a complex influence over binding, being also regulated by cAMP concentration. The positive effect on binding of ionic and bovine serum albumin concentrations, and the negative effect of enzyme preincubation before additions of (H3) cAMP, have also been studied. The importance of these effectors to obtain a high degree of sensitivity in the binding protein method has been assertained.
一种依赖于环磷酸腺苷（cAMP）的蛋白激酶已从兔肌肉中分离并纯化出来。该酶对核苷酸的亲和常数为Ka = 9.3×10⁻⁹ M，最大反应速度Vmax = 0.013×10¹² 摩尔结合的cAMP/1微克蛋白质。研究了不同因素的影响：a）激酶活性抑制剂（I）：增加对cAMP的结合能力，增加的百分比取决于I的量。在存在抑制剂（120微克/100微升）的情况下，亲和常数为Ka = 4.1×10⁻⁹ M，Vmax不变。b）pH的影响：对结合有复杂的影响，也受cAMP浓度调节。还研究了离子和牛血清白蛋白浓度对结合的正向影响，以及在添加（³H）cAMP之前酶预孵育的负向影响。已确定这些效应物对于在结合蛋白方法中获得高度敏感性的重要性。
