Immunoreactivity and sensitivity of peptides from β-casein, which inhibit lactococcal peptidases, to hydrolysis by thermolysin and proteinase from Pseudomonas fluorescens

Thermolysin and metalloproteinase from Pseudomonas fluorescens P1, both standardized to approximately the same activity on methionine enkephalin, degraded readily bovine β-casein (β-CN) fragments 58-70, 58-72, and 193-209. These peptides inhibit 70 kDa intracellular endopeptidase and 95 kDa intracellular aminopeptidase from Lactococcus spp. The degradation patterns of peptides released from each of the 3 fragments were different for thermolysin and Pseudomonas proteinase. The two enzymes cleaved different peptide bonds of β-CN f193-209. Cheddar, Norvegia and Roquefort type cheeses contained peptides reactive with antibodies raised against β-CN f58-70.