However, proteases do not catalyze the hydrolysis of all kinds of proteins. Their action is stereo-selective: Only proteins with a certain tertiary structure will be targeted. The reason is that some kind of orienting force is needed to place the amide group in the proper position for catalysis. The necessary contacts between an enzyme and its substrates (proteins) are created because the enzyme folds in such a way as to form a crevice into which the substrate fits; the crevice also contains the catalytic groups. Therefore, proteins that do not fit into the crevice will not be hydrolyzed. This specificity preserves the integrity of other proteins such as hormones, and therefore the biological system continues to function normally.
The hydrolysis of salts forms the basis of many important processes in the chemical industry and laboratory practice. The partial hydrolysis of tricalcium silicate causes separation of lime during the reaction of portland cement with water. Buffer systems, which are able to maintain constant acidity in a medium, exist because of hydrolysis. Buffer solutions are also very important physiologically, since a constant H + ion concentration is necessary for normal body activity. A number of geological changes in the earth’s crust and the formation of minerals, natural waters, and soils are associated with hydrolysis.