[Study of gelatin hydrolysis by Streptomyces griseus protease using the method of N-terminal analysis]

The ariticle deals with gelatin hydrolysis by the crystalline preparation of the Str. griseus protease. 12.1% of 1080 peptide bonds available in 105 g of protein split for 24 h at 40 C. The bonds of 8-9 types which involve N-end of glycine, serine, phenylalanine, threonine, leucine, valine, glutaminic acid, lysine break at once. The process occurs with delay, and 0.25, 0.5, 6 and 24 h after there occurs a breakage of the 42d, 61st, 117th and131st bonds. The middle size of the peptide chain of the initial protein is 604 amino acid residues, in the hydrolyzate 30, 22, 11.6 and 11.3 residues are found within these intervals, respectively. Main changes occur in the fraction of soluble peptides where number of N-terminal amino acids rises from 25 to 80. Some data are obtained on the total specificity of the Str. griseus protease. It splits mostly the bonds which involve the N-end of glycine (51%), alanine 2%), serine (9%). The content of the definite amino acid in gelatin shows that hydrolysis bonds of serine and threonine accounts for 35.2 and 35.6%, valine and leucine for 23.6 and 24.7%, glycine and alanine for 18.8 and 13%, methionine, lysine, glutaminic and asparagic acids for 7-9%; the proline bonds are not splitted at all. An assumption is advanced on the presence of four groups of bonds in gelatin; the rate of their hydrolysis corresponding to the enzyme specificity. The Str. griseus protease splits as free amino acids 10 mol of serine of 35,5, 5.5 mol of leucine of 26.3, 3.6 mol of threonine of 19.8 and only 4 mol of glycine of 363 available in gelatin.