Characterization of an extracellular glycoprotein inhibitor of trypsin (TI-23) produced by Streptomyces sp. 23

Abstract

The production of an extracellular trypsin inhibitor, TI-23, was found to parallel the growth of Streptomyces sp. 23 at different cultivation temperatures, reaching a m a x i m u m level at late exponential phase. Although the different temperatures (18 ° , 28 ° and 37 ° C) did not greatly affect the growth of the microorganism, they proved to be an important factor for extracellular inhibitory activity. Maximum specific rates of both cell growth and production of the inhibitor were recorded during the cultivation of Streptornyces sp. 23 at 37 ° C. TI-23 proved to be a monomeric glycoprotein containing 17% carbohydrate and differing in amino acid composition from the known extracellular proteinase inhibitors of streptomycetes. The molecular mass of the inhibitor was estimated to be about 13 k D a and the isoelectric point 4.3. The inhibition spectrum of TI-23 included trypsin as well as some microbial alkaline proteinases.