Thromb Haemost 1990; 63(03): 459-463
DOI: 10.1055/s-0038-1645066
Original Article
Schattauer GmbH Stuttgart

Interaction of a Plasmin A-Chain/t-PA B-Chain Hybrid Enzyme with Plasma Inhibitors In Vivo and In Vitro

S Wilson
The Department of Biotechnology, SmithKline Beecham, Great Burgh, Epsom, Surrey, UK
,
P Chamberlain
The Department of Biotechnology, SmithKline Beecham, Great Burgh, Epsom, Surrey, UK
,
I Dodd
The Department of Biotechnology, SmithKline Beecham, Great Burgh, Epsom, Surrey, UK
,
A Esmail
The Department of Biotechnology, SmithKline Beecham, Great Burgh, Epsom, Surrey, UK
,
J H Robinson
The Department of Biotechnology, SmithKline Beecham, Great Burgh, Epsom, Surrey, UK
› Author Affiliations
Further Information

Publication History

Received 15 September 1989

Accepted after revision 23 January 1990

Publication Date:
30 June 2018 (online)

Summary

A hybrid plasminogen activator consisting of the “A” chain of plasmin linked to the “B” chain of rt-PA was inhibited in vitro in human and guinea pig plasmas 4 to 5-fold more rapidly than its parent activator, two-chain t-PA. Using zymographic and autoradiographic techniques together with the use of immunodepleted plasma the major inhibitor was identified as aIpha-2-antiplasmin. The pharmacokinetic profile of the hybrid in guinea pigs was determined by two different methods: disappearance of fibrinolytic activity and removal of radiolabelled hybrid from the circulation. Fibrinolytic activity was cleared rapidly via inhibitory mechanisms, whilst radiolabelled material was cleared considerably more slowly due to the formation of hybrid-inhibitor complexes. When the active site of the hybrid was reversibly acylated inhibitory mechanisms were evaded and a prolonged pharmacokinetic profile of activity was observed.