사람의 양수 중에서 처음으로 세포외성 phospholipase $A_2$ 활성이 있음을 확언하였으며, 출산에 있어서 중요한 prostaglandin의 전구체인 arachidonic acid 제공에 중요한 역활을 할 것이라고 생각된다. 본 효소는 지금까지 보고된 group I이나 group II phospholipase $A_2$와 계변 활성제의 영향이나 monoclonal antibody와의 반응성에서 다른 특성을 갖는 효소로 추정되었으며, 또한 적어도 2종류의 phospholipase $A_2$의 활성이 존재함에 시사되어 금후 더욱 구체적인 검토를 행하여 단백화학적 특성을 규명할 필요가 있다.
Extracellular phospholipase $A_2$ activity has been identified in human amniotic fluid. This enzyme required $Ca^{2+}$ ion and exhibited bimodal pH optimum at pH 7.0 and 9.0. The phospholipase hydrolyzed 1-acyl-2-[1-$^{14}C$]arachidonoylphosphatidylethanolamine to form only [$^{14}C$]arachidonic acid indicating that the enzyme had phospholipase "$A_2$" activity. Ionic and non-ionic detergents caused loss of enzymatic activity. This phospholipase $A_2$ was recognized, in part, by a monoclonal antibody raised against phospholipase $A_2$ from human synovial fluid. This finding suggests that our enzyme is an another type of an extracellular phospholipase $A_2$ which may not belong to the 14 KDa group II phospholipase $A_2$ family.
