Kageyama H.,Nagoya University |
Kageyama H.,Amino Acids Company |
Ueda H.,Ajinomoto Co. |
Tezuka T.,Nagoya University |
And 5 more authors.
Journal of Biochemistry | Year: 2010
Porcine pepsin A and bovine chymosin are typical models of aspartic proteinases. The hydrolytic specificities of these proteinases, along with those of human pepsin A and monkey chymosin, were investigated with 29 peptide substrates that included various P1′ variants of seven parent peptides. From these peptides, AFPLEF↓FREL was preferred by pepsin A and chymosin, while its P1' variant, AFPLEF↓EREL was preferred by bovine chymosin. Porcine and human pepsin A showed similar hydrolytic specificities, strongly preferring a hydrophobic/aromatic residue at P1' of any type of peptide. This specificity is well explained by the very hydrophobic nature of the S1' subsite that consists of Tyr189, Ile213, Ile300, Met289, Val/Leu291 and Leu298. The first three residues are well conserved in pepsin family enzymes. Although bovine and monkey chymosin showed similar P1′ specificity, bovine chymosin preferred peptides having Glu at P1', while monkey chymosin preferred peptides having Lys at P1'. The dual characteristics of chymosin are due to the occurrence of polar/charged residues in the S1'; subsite, such as Glu/Asp289, Gln298 and Lys/Gln299, which are different from the S1' subsite of pepsin A. Molecular models suggest that Glu in position 289 of bovine chymosin and Asp in position 289 of monkey chymosin are responsible for the difference in P1' specificities between the chymosins.
Asa R.,Obihiro University of Agriculture and Veterinary Medicine |
Tanaka A.,Obihiro University of Agriculture and Veterinary Medicine |
Uehara A.,Obihiro University of Agriculture and Veterinary Medicine |
Uehara A.,Amino Acids Company |
And 9 more authors.
Asian-Australasian Journal of Animal Sciences | Year: 2010
Effects of protease-resistant antimicrobial substances (PRA) produced by Lactobacillus plantarum and Leuconostoc citreum on rumen methanogenesis were examined using the in vitro continuous methane quantification system. Four different strains of lactic acid bacteria, i) Lactococcus lactis ATCC19435 (Control, non-antibacterial substances), ii) Lactococcus lactis NCIMB702054 (Nisin-Z), iii) Lactobacillus plantarum TUA1490L (PRA-I), and iv) Leuconostoc citreum JCM9698 (PRA-2) were individually cultured in GYEKP medium. An 80 ml aliquot of each supernatant was inoculated into phosphate-buffered rumen fluid. PRA-1 remarkably decreased cumulative methane production, though propionate, butyrate and ammonia N decreased. For PRA-2, there were no effects on CH 4 and CO2 production and fermentation characteristics in mixed rumen cultures. The results suggested that PRA-1 reduced the number of methanogens or inhibited utilization of hydrogen in rumen fermentation.