Complete primary structure of thermitase from <i>Thermoactinomyces vulgaris</i> and its structural features related to the subtilisin‐type proteinases

Abstract

Thermitase, a thermostable alkaline proteinase, consists of a single polypeptide chain, containing 279 amino acid residues ( M r = 28 369). The enzyme shows remarkable structural features of proteinases of the subtilisin type as shown by pronounced sequential homologies. The amino acid replacements, insertions and deletions observed when the amino acid sequence of the enzyme is compared with the sequences of several subtilisins are discussed with respect to substrate specificity and expected tertiary structure. The existence of a cysteinecontaining subgroup of subtilisin‐like proteinases is postulated.