Reaction: Endopeptidase activity with very broad specificity, although some subsite preferences have been noted, e.g. large hydrophobic residues in the P1 and P4 positions, and Pro in the P2 position [1,2]. Best known for its action on caseins, although it has been shown to hydrolyse hemoglobin and oxidized insulin B chain
Other names: CEP; extracellular lactococcal proteinase; lactococcal cell wall-associated proteinase; lactococcal cell envelope-associated proteinase; lactococcal proteinase; PrtP
Comments: associated with the cell envelope of Lactococcus lactis and attached via a C-terminal membrane anchor sequence. Responsible for the hydrolysis of casein in milk and the provision of peptides essential to cell growth. Important in cheese making and the production of lactic casein, being required for rapid growth to high cell densities with concomitant production of adequate levels of lactic acid. Specificity differences between lactocepins from different starter strains may be partly responsible for imparting different flavour qualities to cheese [4]. In peptidase family S8 (subtilisin family)
Links to other databases: BRENDA, EXPASY, KEGG, MEROPS, Metacyc, CAS registry number: 205510-58-3
References
1. Visser, S., Robben, A.J.P.M. and Slangen, C.J. Specificity of a cell-envelope-located proteinase (PIII-type) from Lactococcus lactis subsp. cremoris AM1 in its action on bovine beta-casein. Appl. Microbiol. Biotechnol. 35 (1991) 477-483. [PMID: 1367552]
2. Monnet, V., Ley, J.P. and Gonzalez, S. Substrate specificity of the cell envelope-located proteinase of Lactococcus lactis subsp. lactis NCDO763. Int. J. Biochem. 24 (1992) 707-718. [PMID: 1592148]
3. Exterkate, F.A., Alting, A.C. and Bruinenberg, P.G. Diversity of cell envelope proteinase specificity among strains of Lactococcus lactis and its relationship to charge characteristics of the substrate-binding region. Appl. Environ. Microbiol. 59 (1993) 3640-3647. [PMID: 8285671]
4. Pritchard, G.G. and Coolbear, T. The physiology and biochemistry of the proteolytic system in lactic acid bacteria. FEMS Microbiol. Rev. 12 (1993) 179-206. [PMID: 8398214]