Proteases are among the technically most important of all enzymes. For washing and cleaning agents they are the longest-established enzymes, contained in practically all modern high-performance washing and cleaning agents. They cause the breakdown of protein-containing stains on the material to be cleaned. Among these in turn, proteases of the subtilisin type (subtilases, subtilopeptidases, EC 3.4.21.62), which are categorized among the serine proteases because of the catalytically effective amino acids, are particularly important. They act as nonspecific endopeptidases and hydrolyze any acid-amide bonds that are located within peptides or proteins. Their optimum pH is usually in the markedly alkaline range. An overview of this family is offered, for example, by the article “Subtilases: subtilisin-like proteases” by R. Siezen, in “Subtilisin enzymes” pp. 75-95, edited by R. Bott and C. Betzel, New York, 1996. Subtilases are formed naturally by microorganisms; among them, the subtilisins formed and secreted by Bacillus species are to be mentioned in particular as the most significant group within the subtilases.
Examples of proteases of the subtilisin type used with preference in washing and cleaning agents are the subtilisins BPN′ and Carlsberg, protease PB92, subtilisins 147 and 309, the protease from Bacillus lentus, in particular from Bacillus lentus DSM 5483, subtilisin DY, and the enzymes (to be classified, however, as subtilases and no longer as subtilisins in the strict sense) thermitase, proteinase K, and the proteases TW3 and TW7, as well as variants of the aforesaid proteases that exhibit an amino acid sequence modified as compared with the initial protease. Proteases are modified, in controlled or random fashion, using methods known from the existing art, and are thereby optimized, for example, for use in washing and cleaning agents. These include point mutagenesis, deletion or insertion mutagenesis, or fusion with other proteins or protein parts. Correspondingly optimized variants are thus known for most proteases known from the existing art.
The International Patent Application WO 03/054185 discloses alkaline proteases from Bacillus gibsonii (DSM 14391), including for use thereof in washing or cleaning agents. This strain was deposited on Mar. 1, 2001, in accordance with the Budapest Treaty on the International Recognition of the Deposit of Microorganisms of Apr. 28, 1977, at the German Collection of Microorganisms and Cell Cultures [Deutsche Sammlung von Mikroorganismen and Zellkulturen GmbH], Inhoffenstrasse 7B, D-38124 Braunschweig under the designation ID 01-192 and entry number DSM 14391. These proteases exhibit considerable differences in amino acid sequence as compared with the proteases recited above, so that an identity comparison of the amino acid sequences yields identity values that are below 80% identity. For the alkaline proteases from Bacillus gibsonii (DSM 14391), only a few protease variants optimized for use in washing and cleaning agents are so far known in the existing art.