Metabolism of small peptides in rumen fluid: accumulation of intermediates during hydrolysis of alanine oligomers, and comparison of peptidolytic activities of bacteria and protozoa

R. J. Wallace, N. McKain, C. J. Newbold

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Abstract

Oligopeptides of l-alanine up to ala5, were incubated in vitro in either strained rumen fluid or suspensions of mixed rumen bacteria. The disappearance of substrates and formation of products were measured for 40 min, by which time ala3, ala4 and ala5 were almost totally hydrolysed. Ala2 was more slowly hydrolysed, and accumulated in incubations with the other peptides. The pattern of formation of ala2 but not ala3 from ala4, and ala3 and ala2 but not ala4 from ala5, suggested that the peptides were being hydrolysed by a dipeptidyl peptidase mechanism. Three different sheep receiving different diets gave similar results. Neither substrates nor products appeared to be accumulated intracellularly, except for ala2, and then only if protozoa were present. Protozoa were more active than bacteria in ala2 hydrolysis, whereas bacteria had greater activities with higher homologues. Similar preferences were observed with glycine peptides, although unlike alanine peptides gly3 and gly5 were more slowly degraded than the dimer. These experiments suggest that protozoa are of importance in the accumulation and hydrolysis of dipeptides, whereas bacteria are responsible for the breakdown of larger molecules by a dipeptidyl peptidase mechanism that does not appear to involve accumulation within the cell.
Original languageEnglish
Pages (from-to)191-199
Number of pages9
JournalJournal of the Science of Food and Agriculture
Volume50
Issue number2
DOIs
Publication statusPublished - 1990

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Rumen
rumen fluids
Alanine
alanine
Protozoa
Hydrolysis
hydrolysis
Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
peptides
Bacteria
Peptides
metabolism
peptidases
bacteria
oligopeptides
Oligopeptides
rumen bacteria
dipeptides
Dipeptides
glycine (amino acid)

Cite this

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title = "Metabolism of small peptides in rumen fluid: accumulation of intermediates during hydrolysis of alanine oligomers, and comparison of peptidolytic activities of bacteria and protozoa",
abstract = "Oligopeptides of l-alanine up to ala5, were incubated in vitro in either strained rumen fluid or suspensions of mixed rumen bacteria. The disappearance of substrates and formation of products were measured for 40 min, by which time ala3, ala4 and ala5 were almost totally hydrolysed. Ala2 was more slowly hydrolysed, and accumulated in incubations with the other peptides. The pattern of formation of ala2 but not ala3 from ala4, and ala3 and ala2 but not ala4 from ala5, suggested that the peptides were being hydrolysed by a dipeptidyl peptidase mechanism. Three different sheep receiving different diets gave similar results. Neither substrates nor products appeared to be accumulated intracellularly, except for ala2, and then only if protozoa were present. Protozoa were more active than bacteria in ala2 hydrolysis, whereas bacteria had greater activities with higher homologues. Similar preferences were observed with glycine peptides, although unlike alanine peptides gly3 and gly5 were more slowly degraded than the dimer. These experiments suggest that protozoa are of importance in the accumulation and hydrolysis of dipeptides, whereas bacteria are responsible for the breakdown of larger molecules by a dipeptidyl peptidase mechanism that does not appear to involve accumulation within the cell.",
author = "Wallace, {R. J.} and N. McKain and Newbold, {C. J.}",
note = "75",
year = "1990",
doi = "10.1002/jsfa.2740500207",
language = "English",
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pages = "191--199",
journal = "Journal of the Science of Food and Agriculture",
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TY - JOUR

T1 - Metabolism of small peptides in rumen fluid

T2 - accumulation of intermediates during hydrolysis of alanine oligomers, and comparison of peptidolytic activities of bacteria and protozoa

AU - Wallace, R. J.

AU - McKain, N.

AU - Newbold, C. J.

N1 - 75

PY - 1990

Y1 - 1990

N2 - Oligopeptides of l-alanine up to ala5, were incubated in vitro in either strained rumen fluid or suspensions of mixed rumen bacteria. The disappearance of substrates and formation of products were measured for 40 min, by which time ala3, ala4 and ala5 were almost totally hydrolysed. Ala2 was more slowly hydrolysed, and accumulated in incubations with the other peptides. The pattern of formation of ala2 but not ala3 from ala4, and ala3 and ala2 but not ala4 from ala5, suggested that the peptides were being hydrolysed by a dipeptidyl peptidase mechanism. Three different sheep receiving different diets gave similar results. Neither substrates nor products appeared to be accumulated intracellularly, except for ala2, and then only if protozoa were present. Protozoa were more active than bacteria in ala2 hydrolysis, whereas bacteria had greater activities with higher homologues. Similar preferences were observed with glycine peptides, although unlike alanine peptides gly3 and gly5 were more slowly degraded than the dimer. These experiments suggest that protozoa are of importance in the accumulation and hydrolysis of dipeptides, whereas bacteria are responsible for the breakdown of larger molecules by a dipeptidyl peptidase mechanism that does not appear to involve accumulation within the cell.

AB - Oligopeptides of l-alanine up to ala5, were incubated in vitro in either strained rumen fluid or suspensions of mixed rumen bacteria. The disappearance of substrates and formation of products were measured for 40 min, by which time ala3, ala4 and ala5 were almost totally hydrolysed. Ala2 was more slowly hydrolysed, and accumulated in incubations with the other peptides. The pattern of formation of ala2 but not ala3 from ala4, and ala3 and ala2 but not ala4 from ala5, suggested that the peptides were being hydrolysed by a dipeptidyl peptidase mechanism. Three different sheep receiving different diets gave similar results. Neither substrates nor products appeared to be accumulated intracellularly, except for ala2, and then only if protozoa were present. Protozoa were more active than bacteria in ala2 hydrolysis, whereas bacteria had greater activities with higher homologues. Similar preferences were observed with glycine peptides, although unlike alanine peptides gly3 and gly5 were more slowly degraded than the dimer. These experiments suggest that protozoa are of importance in the accumulation and hydrolysis of dipeptides, whereas bacteria are responsible for the breakdown of larger molecules by a dipeptidyl peptidase mechanism that does not appear to involve accumulation within the cell.

U2 - 10.1002/jsfa.2740500207

DO - 10.1002/jsfa.2740500207

M3 - Article

VL - 50

SP - 191

EP - 199

JO - Journal of the Science of Food and Agriculture

JF - Journal of the Science of Food and Agriculture

SN - 0022-5142

IS - 2

ER -