Fumaric acid, anti-thrombin substance from Rhizopus javanicus.

An anti-thrombin substance (M2) was isolated from a culture broth of Rhizopus javanicus. Accumulation of M2 reached a maximum peak after 14 to 15 days of incubation and then decreased. The yield of M2 was 500 mg from 1 L of culture broth. M2 inhibited thrombin activity, and its 50% inhibition concentration in a reaction mixture containing 50 microL of 12.5 NIH unit/mL thrombin and 200 microL of 0.33% bovine fibrinogen was 63 microM. M2 had a specific activity for thrombin, but it was less responsive to plasmin, tissue-type plasminogen activator, urokinase, plasma kallikrein and glandular kallikrein. The structure of M2 was identified as fumaric acid by elementary analysis, FAB/MS, 1H-NMR, 13C-NMR and IR spectra.