[Mass-spectrometric determination of specificity of proteinases]

Analysis of methods of the proteinase substrate specificity determination revealed that Michaelis constants found from the rates of hydrolysis of small synthetic substrates cannot be a good measure of selectivity, especially for proteinases of broad specificity used for hydrolysis of substrates of high molecular mass with multiple cleavage sites. Mass-spectrometric studies (ERIAD) of the hydrolysis of the insulin B chain with trypsin, chymotrypsin, and proteinase I showed that monitoring of the reaction mixtures by means of this technique gives more reliable information on the selectivity of proteinase towards high-molecular substrates.