Thromb Haemost 1981; 45(02): 107-109
DOI: 10.1055/s-0038-1650144
Original Article
Schattauer GmbH Stuttgart

Plasmin Potency Estimates: Influence of the Substrate Used in Assay

Roger D Philo
The Division of Blood Products, National Institute for Biological Standards and Control, Hampstead, London, U. K.
,
Patrick J Gaffney
The Division of Blood Products, National Institute for Biological Standards and Control, Hampstead, London, U. K.
› Author Affiliations
Further Information

Publication History

Received 28 July 1980

Accepted 12 January 1981

Publication Date:
05 July 2018 (online)

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Summary

A urokinase-activated plasmin (UK-plasmin) preparation was assayed against the International Reference Preparation for Plasmin (IRP-plasmin) using caseinolytic, fibrinolytic, fibrinogenolytic and chromogenic assay methods. The relative potency (using multi-dose bioassays) was estimated by the fibrinolytic method to be about twice that obtained by the caseinolytic, fibrinolytic and chromogenic assay methods. It was found that the UK-plasmin binds to fibrin to a greater extent than does the IRP-plasmin and this is advanced as an explanation for the discrepancy between assay methods. This difference in the binding of the two plasmins to fibrin may mean that it will be difficult to compare the fibrinolytic activities of various plasmin preparations.

It is also shown that, during thermal degradation, the IRP-plasmin loses fibrinolytic activity more rapidly than amidolytic activity.