Patent ID: 6074837
Filing Date: 2000-06-13
Classification: C12Q,G01N

Abstract:
In an assay for determining all unknown fibrin monomer concentration in a first plasma sample, said assay comprising contacting said first plasma sample with plasminogen, tissue plasminogen activator, a substrate which undergoes a color change when plasmin is generated, and after a suitable incubation period correlating any color change to that undergone by a second plasma sample containing fibrin monomer of a known concentration to give an indication of the fibrin monomer concentration in said first plasma sample, wherein the improvement, comprises the fibrin monomer of known concentration in said second plasma is a modified fibrinogen, the modified fibrinogen obtained by a process comprising the following steps: partially reducing 3 to 25 micromolar fibrinogen with 0.25 millimole per nanomole of said fibrinogen with a reducing agent at 30-40.degree. C. under non-denaturing conditions in the absence of divalent cations for 0.5 to 1.5 hours, then (2) blocking thiol groups of any free cysteines formed during step (1) by reacting the product of step (1) with a blocking agent that does not cause precipitation of the product of step (2), then (3) reacting the product of step (2) with a clotting enzyme in a physiological buffer in the absence of divalent cations to release fibrinopeptides A and B, and (4) terminating the activity of said clotting enzyme.