Abe K
Third Department of Internal Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Hokkaido Igaku Zasshi. 1993 May;68(3):368-76.
Although the cascade theory is the main story which explains mechanisms of blood coagulation, the interactions among the enzymes (i. e. coagulation factors) involved in this cascade has not been well characterized. In this paper, protein kinase C (phospholipid/Ca(2+)-dependent protein kinase) was found to involve in the phosphorylation of the coagulation factors (I, II and VIII), which require both phospholipid and Ca2+ for their activations. In the phosphorylation of prothrombin (blood coagulation factor II), the apparent Km value of 0.86 microM was obtained. The value was comparable to that reported for most known substrates of protein kinase C. A 2-dimensional separation-analysis revealed that serine residue was apparently phosphorylated by PKC. The phosphorylation was inhibited by protein kinase C inhibitors such as gossypol and staurosporine. Prothrombin seemed to have a tendency to be increased in its coagulation activity (1. e. shortening of prothrombin time), when it was phosphorylated by PKC. These phenomena suggest that PKC may be involved in the mechanism of blood coagulation.
尽管瀑布学说（级联理论）是解释血液凝固机制的主要理论，但参与该级联反应的酶（即凝血因子）之间的相互作用尚未得到充分表征。在本文中，发现蛋白激酶C（磷脂/钙依赖性蛋白激酶）参与凝血因子（I、II和VIII）的磷酸化，这些凝血因子的激活需要磷脂和钙离子。在凝血酶原（血液凝固因子II）的磷酸化过程中，获得了0.86微摩尔的表观米氏常数。该值与报道的蛋白激酶C的大多数已知底物的值相当。二维分离分析表明，丝氨酸残基明显被蛋白激酶C磷酸化。该磷酸化被棉酚和星形孢菌素等蛋白激酶C抑制剂抑制。当凝血酶原被蛋白激酶C磷酸化时，其凝血活性（即凝血酶原时间缩短）似乎有增加的趋势。这些现象表明蛋白激酶C可能参与血液凝固机制。
