Degradation and debittering of a tryptic digest from beta-casein by aminopeptidase N from Lactococcus lactis subsp. cremoris Wg2

Abstract

The mode of action of purified aminopeptidase N from Lactococcus lactis subsp. cremoris Wg2 on a complex peptide mixture of a tryptic digest from bovine 1-casein was analyzed. The oligopeptides produced in the tryptic digest before and after aminopeptidase N treatment were identified by analysis of the N-and C-terminal amino acid sequences and amino acid compositions of the isolated peptides and by on-line liquid chromatography-mass spectrometry. Incubation of purified peptides with aminopeptidase N resulted in complete hydrolysis of many peptides, while others were only partially hydrolyzed or not hydrolyzed. The tryptic digest of 13-casein exhibits a strong bitter taste, which corresponds to the strong hydrophobicity of several peptides in the tryptic digest of 1-casein. The degradation of the "bitter" tryptic digest by aminopeptidase N resulted in a decrease of hydrophobic peptides and a drastic decrease of bitterness of the reaction mixture.

Proteolytic activity of lactobacilli in a model goats' milk curd system

“…casei IFPL 99, which indicates a higher level of debittering activity by IFPL 731, possibly related to the strain's high level of aminopeptidase activity (Requena et al 1993). Tan et al (1993) reported degradation In conclusion, differences in proteolytic abilities of lactobacilli strains tested were detected using goats' milk curd slurries, even though the strains exhibited similar peptide profiles. Given that this model system shares similar characteristics with cheeses, it can be used to screen starter bacteria and non-starter bacteria as adjuncts for cheese making, and also to check what contribution they might make to cheese ripening.…”

Technological characterization of lactic acid bacteria from Tenerife cheese

“…Lactobacilli showed the highest aminopeptidase activity. As aminopeptidases play an important role in the hydrolysis of bitter peptides and in amino acid liberation (Tan et al. , 1993; Sasaki et al.…”

Recombinant Lactococcus starters as a potential source of additional peptidolytic activity in cheese ripening

“…The role of aminopeptidases in debittering has been verified by using purifed aminopeptidase enzymes (Minagawa et al . 1989; Tan et al . 1993; Bouchier et al .…”