Peptides inhibitory to endopeptidase and aminopeptidase from Lactococcus lactis ssp. lactis MG1363, released from bovine beta-casein by chymosin, trypsin or chymotrypsin.
Peptides inhibitory to the 70-kDa endopeptidase (PepO) from the cytoplasm of Lactococcus lactis ssp. lactis MG1363 were isolated from the supernatant (pH 4.6) of chymosin, tryptic and alpha-chymotryptic hydrolysates of beta-casein (beta-CN) by reversed-phase HPLC and identified by sequencing and mass spectrometry. Chymosin released beta-CN f193-209, kinetic constant (Ki) of which for inhibition of PepO was 60 microM. This peptide also inhibited (Ki = 1700 microM) the 95-kDa aminopeptidase (PepN) from L. lactis ssp. lactis MG 1363. Trypsin released two PepO-inhibitory peptides: one, beta-CN f69-97, was not degradable by PepO (Ki = 4.7 microM), while the other, beta-CN f141-163, was degradable by PepO but competitively inhibited hydrolysis of methionine enkephalin by PepO. A peptide, beta-CN f69-84, which inhibited PepO with a Ki of 8.1 microM, was isolated from the alpha-chymotryptic hydrolysate. Peptides released from beta-CN by trypsin or chymotrypsin had very little inhibitory activity against PepN. PepO degraded beta-CN f193-209 very slowly compared with the hydrolysis of methionine enkephalin. All four inhibitory peptides (beta-CN f193-209, f69-97, f69-84, f141-163) were readily degraded by thermolysin.
Stepaniak
L
L
Department of Food Science, Agricultural University of Norway, As, Norway.
Gobbetti
M
M
Sørhaug
T
T
Fox
P F
PF
Højrup
P
P
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000037:antagonists & inhibitors*; D000818:Animals; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors; D002364:Caseins / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D012085:Chymosin / Q000378:metabolism; D002918:Chymotrypsin / Q000378:metabolism; D007700:Kinetics; D013294:Lactococcus lactis / Q000201:enzymology*; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011480:Protease Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism
D001426:Bacterial Proteins; D002364:Caseins; D010446:Peptide Fragments; D011480:Protease Inhibitors; D000626:Aminopeptidases; D012697:Serine Endopeptidases; D002918:Chymotrypsin; D014357:Trypsin; D012085:Chymosin; D008666:Metalloendopeptidases; C080385:oligopeptidase PepO