The activation of plasminogen to an active fibrinolytic enzyme, plasmin, by Streptokinase and Staphylokinase was studied using caseinolytic assay method. The Staphylokinase producing microorganism was selected among 15 β-hemolytic Staphylococci and that of Streptokinase was purchased from ATCC. Staphylokinase was purified by CM-cellulose ion exchange chromatography and Seph 4B-EACA column chromatography. Ammonium sulfate fractionation and DEAE-cellulose ion exchange chromatography were used to purify Streptokinase.
Both of them showed a very limitted substrate specificity toward plasminogen, and their catalytic activities were inhibited by the presence of macromolecular proteins such as bovine serum albumin and casein.
Both activators showed a similar mode of catalytic action on plasminogen, but their nature and molecular properties were found to be different from that of human urokinase. Based on kinetic experiments and other inhibition study, the reaction mode of these two activators was discussed.
Also, by chemical modification, the ionic interaction between Streptokinase and Plasminogen to form complex was stuied.
SK 와 SLK 에 의해 Plasminogen 이 plasmin 으로 활성화되는 기작을 연구하였다. 변형된 caseinolytic method 를 이용해서 여러가지 성질을 연구한 결과 다음과 같은 사실을 알 수 있었다.
첫째, SK 도 SLK와 같이 casein 에 의해 inhibition을 받는데, 그 이유는 SK 와의 결합을 Pg 와 다투는 competition 으로 추정된다.
둘째, 위의 성질을 이용해서 새로운 caseinolytic method 를 만든 다음, SK 와 SLK의 성질을 비교해 보았다. 여기서 SLK의 성질이 SK 와 극히 유사함을 보게 되었고, 그에따라 SLK의 작용기작은 SK 와 비슷한 것이며 UK 와는 다른 것이리라 결론지었다.
셋째, SK 와 Pg 가 complex 를 이루는 데에는 SK 의 amino group 과 carboxyl-group, 그리고 Pg 의 상대되는 group 사이의 작용이 중요함을 증명하였다. 이러한 ionic interaction 은 이들의 complex formation 을 유도하는 것으로 추정된다.