Specificity of a cell wall proteinase fromStreptococcus lactisNCDO763 towards bovine β-casein

A cell wall proteinase from Streptococcus lactis liberated, with a molar ratio of enzyme over substrate of approx. 10−5, at least 5 peptides from the C-terminal part of β-casein. The substrate specificity of the enzyme appears to be low. The occurrence of a hydrophobic residue at position P3 seems to be the only feature common to 4 of the 5 susceptible peptide bonds. The released fragments have features found in peptides producing a bitter taste.