Limited Proteolysis as a Tool to Detect Structure and Dynamic Features of Globular Proteins: Studies on Thermolysin

Abstract

In analogy to all enzymatic reactions, the proteolytic cleavage of a polypeptide chain occurs only if the site of cleavage can bind and adapt itself in a specific way to the stereochemistry of the active site of the protease. This is difficult to achieve with native globular proteins, whereas denatured proteins are much more susceptible to proteolysis. In a number of cases, an extraordinary lability to enzymatic hydrolysis of a very small number of specific bonds in a native globular protein has been observed and this selective peptide bond fission has been termed “limited proteolysis”. It is conceivable to suggest that the sites of limited proteolysis in a native globular protein are dictated solely by the stereochemistry of the protein substrate, if a protease of low specificity is employed. In addition, some motility of the substrate protein at the site of cleavage would be required for a proper adaptation to the active site of the protease (Neurath and Walsh 1976; Neurath 1980, 1986).