A trypsin inhibitor with thermal and pH stability, designated M ercine, was prepared from seeds of G lycine max ( L .) merr. The preparation procedure involved ammonium sulfate precipitation, ion-exchange chromatography on CM- Sephadex C-50, affinity chromatography on Affi-gel blue gel. The 20 N-terminal amino acid sequences were determined to be DEYSKPCCDLCMCTRRMPPQ, demonstrating highly homologies with the sequence of Bowman- Birk type trypsin inhibitors. The molecular mass and isoelectric point of the inhibitor were estimated by SDS- PAGE and isoelectric focusing to be 17.9 kD and 4.6, respectively. Trypsin could be completely inhibited by M ercine when the molar ratio was 8.0. The inhibitory activity of M ercine was unaffected after exposure to temperatures up to 80C, or within the pH range 2-12. Besides inhibiting trypsin-chymotrypsin, the inhibitor M ercine demonstrated additional antifungal activity toward the species of A lternaria alternate, F usarium oxysporum, P ythium aphanidermatum, P hysalospora piricola and B otrytis cinerea. Practical Applications We here report, for the first time, not only the trypsin inhibitor's preparation, but also its N-terminal amino acid sequence and antifungal activity against a series of phytopathogenic fungi. The aforementioned activities shown by trypsin inhibitor, provide further evidence for the potential significance in agriculture. [ABSTRACT FROM AUTHOR]