PepS from Streptococcus thermophilus. A new member of the aminopeptidase T family of thermophilic bacteria.

摘要: The proteolytic system of lactic acid bacteria is essential for bacterial growth in milk but also the development organoleptic properties dairy products. Streptococcus thermophilus widely used industry. In comparison with model Lactococcus lactis, S. thermophilus possesses two additional peptidases (an oligopeptidase and aminopeptidase PepS). To understand how grows milk, we purified characterized this aminopeptidase. PepS a monomeric metallopeptidase ≈ 45 kDa optimal activity range pH 7.5–8.5 at 55 °C on Arg-paranitroanilide as substrate. exhibits high specificity towards peptides possessing arginine or aromatic amino acids N-terminus. From N-terminal protein sequence PepS, deduced degenerate oligonucleotides amplified corresponding gene by successive PCR reactions. amino-acid has identity (40–50%) T family from thermophilic extremophilic bacteria; thus propose classification new member family. view its substrate specificity, could be involved both supplying acids, products’ flavour, hydrolysing bitter liberating which are important precursors aroma compounds.