FOLLICULAR-FLUID FROM HUMAN OVARIES CONTAINS PLASMA KALLIKREIN IN FREE AND IN COMPLEX WITH A(2)-MACROGLOBULIN

Follicular fluid from human ovaries obtained in in vitro fertilization procedures contained substantial proteinase activities toward synthet ic, arginine-containing endopeptidase substrates. Using Pro-Phe-Arg-4- methylcoumaryl-7-amide as a marker for activity, two enzymes, designat ed human fluid serine proteinase-1 (hFSP-1) and -2 (hFSP-2), were isol ated. The molecular weights of intact hFSP-1 and hFSP-2 were estimated to be approximately 90,000 and 730,000, respectively. They exhibited virtually identical substrate specificities and inhibition profiles wh en tested for substrates and inhibitors with low molecular weight. Pol ypeptide proteinase inhibitors, such as soybean trypsin inhibitor and aprotinin, strongly inhibited hFSP-1, but only inhibited hFSP-2 to a l imited extent. These results, together with those of electrophoretic a nd immunological characterization, revealed that hFSP-1 and hFSP-2 are free plasma kallikrein and the enzyme in complex with the plasma inhi bitor alpha(2)-macroglobulin, respectively. hFSP-1 activated human sin gle-chain precursor tissue-type plasminogen activator. This study also indicates that the plasma kallikrein present in follicular fluid prob ably comes from the liver.