[Purification of the extracellular trypsin inhibitor from Actinomyces janthinus 118]

From the culture liquid filtrate of Actinomyces janthinus 118 a trypsin inhibitor (TI-AjI) was isolated by sulphate ammonium precipitation, DEAE-cellulose chromatography, QAE-Sephadex chromatography and two-fold crystallization. The resultant preparation was homogeneous during polyacrylamide gel electrophoresis and ultracentrifugation. As measured by gel filtration, the TI-AjI molecular weight was estimated to be 13,000+/-1,000. The culture liquid of Act. janthinus 118 was found to contain another substance with anti-trypsin activity that differed from TI-AjI in its molecular weight.