Hostname: page-component-586b7cd67f-t7czq Total loading time: 0 Render date: 2024-11-30T02:30:22.875Z Has data issue: false hasContentIssue false
  • English
  • Français

Characteristics of the rumen proteolysis of fraction I (18S) leaf protein from lucerne (Medicago sativa L)

Published online by Cambridge University Press:  09 March 2007

J. H. A. Nugent  and
J. L. Mangan
J. H. A. Nugent
Affiliation:
Department of Biochemistry, ARC Institute of Animal Physiology, Babraham, Cambridge CB2 4AT
J. L. Mangan
Affiliation:
Department of Biochemistry, ARC Institute of Animal Physiology, Babraham, Cambridge CB2 4AT
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

1. The rate of proteolysis of fraction 1 (18S) leaf protein in the rumen of sheep and cattle was affected by diet and the rate on fresh lucerne (Medicago sativa L) was three to nine times the rate on a hay + concentrate diet.

2. Simultaneous rumen fermentations in vivo and in an artificial rumen showed that the rates of proteolysis of fraction I in vitro was approximately 80% of the rates in sheep.

3. Using 14C uniformly-labelled fraction I protein at low concentrations, proteolysis exhibited 1st-order kinetics. Over a wide range of protein concentrations the velocity v. substrate concentration curve showed Michaelis–Menten characteristics typical of an enzyme-catalysed reaction. With rumen fluid from a hay + concentrate-fed sheep the maximum velocity was 2.6 mg protein nitrogen/1 per min and the Michaelis constant was 75 mg nitrogen/1.

4. Rapid adsorption of 14C-labelled fraction I protein onto bacterial cells preceded proteolysis.

5. Sucrose-density-gradient analysis showed initial incorporation of 14C from protein into rumen bacteria followed by partial transfer to rumen protozoa.

6. No peptides were detected during proteoiysis showing that the rate-limiting step occurred during the initial stages of proteolysis. Only small amounts of free amino acids were released except for leucine, isoleucine, valine and ornithine, which showed significantly increased levels.

7. Volatile fatty acids were the main 14C-labelied end products and were rapidly produced in descending concentrations: acetate > propionate > 3-methyl + 2-methyl butyrate > butyrate > isobutyrate > valerate.

Type
Papers on General Nutrition
Information
British Journal of Nutrition , Volume 46 , Issue 1 , July 1981 , pp. 39 - 58
Copyright
Copyright © The Nutrition Society 1981

References

REFERENCES

Allison, M. J. (1969). J. Anim. Sci. 29, 797.CrossRefGoogle Scholar
Black, J. L., Beever, D. E., Faichney, G. J., Howarth, B. R. & Graham, N.McC. (1981) Argic. Systems. (In the Press).Google Scholar
Blackburn, T. H. & Hullah, W. A. (1974). Can. J. Microbiol. 20, 435.CrossRefGoogle Scholar
Blaxter, K. L. & Martin, A. K. (1962). Br. J. Nutr. 16, 397.CrossRefGoogle Scholar
Broderick, G. A. (1978). J. Nutr. 108, 181.CrossRefGoogle Scholar
Burroughs, W., Trenkle, A. & Vetter, R. L. (1974). Vet. Med. Small Anim. Clin. 69, 713.Google Scholar
Chalmers, M. I., Cuthbertson, D. P. & Synge, R. L. M. (1954). J. agric. Sci., Camb. 44, 254.CrossRefGoogle Scholar
Coleman, G. S. (1975). In Digestion and Metabolism in the Ruminant, p. 149 [McDonald, I. W. and Warner, A. C. I., editors]. University of New England Publishing Unit: Armidale, N. S. W., Australia.Google Scholar
Dawson, R. M. C. & Hemington, N. (1974). Br. J. Nutr. 32, 327.CrossRefGoogle Scholar
Harrison, F. A. (1974). J. Physiol., Lond. 242, 20P.Google Scholar
Hazlewood, G. P., Jones, G. A. & Mangan, J. L. (1981). J. gen Microbiol. (In the Press).Google Scholar
Hazlewood, G. P. & Nugent, J. H. A. (1978). J. gen. Microbiol. 106, 369.CrossRefGoogle Scholar
Henderickx, H. & Martin, J. (1963). Compt. Rend. Rech. IRSIA, Brussels 31, 7.Google Scholar
Hydén, S. (1956). Kungl. Lantbr. Annal 22, 139.Google Scholar
James, A. T. & Piper, E. A. (1963). Analyt. Chem. 35, 515.CrossRefGoogle Scholar
Jarrett, I. G. (1948). J. Coun. Scient. ind. Res. Aust. 21, 311.Google Scholar
Jones, W. T. & Mangan, J. L. (1976). J. agric. Sci. Camb. 86, 495.CrossRefGoogle Scholar
Kawashima, N. & Wildman, S. G. (1970). A. Rev. Plant Physiol. p. 325.CrossRefGoogle Scholar
McArthur, J. M. & Miltimore, J. F. (1961). Can. J. Anim. Sci. 41, 187.CrossRefGoogle Scholar
McDonald, I. W. & Hall, R. J. (1959). Biochem. J. 67, 400.CrossRefGoogle Scholar
McDougall, E. I. (1948). Biochem. J. 43, 99.CrossRefGoogle Scholar
Mahadevan, S., Erfle, J. D. & Sauer, F. D. (1980). J. Anim. Sci. 50, 723.CrossRefGoogle Scholar
Mangan, J. L. (1972). Br. J. Nutr. 27, 261.CrossRefGoogle Scholar
Mangan, J. L. & Bounden, J. (1965). 3rd Technicon Amino Acid Colloquium p. 46. Tarrytown, New York: Technicon Instruments Corp.Google Scholar
Mangan, J. L., Jones, W. T., Nugent, J. H. A. & Jordan, D. J. (1977). Proc. 11th FEBS Mtg, Copenhagen A3-2, 903.Google Scholar
Mangan, J. L., Vetter, R. L., Jordan, D. J. & Wright, P. C. (1976). Proc. Nutr. Soc. 35, 95A.Google Scholar
Mangan, J. L. & West, J. (1977). J. agric. Sci., Camb. 89, 3.CrossRefGoogle Scholar
Miller, E. L., Balch, C. C., Orskov, E. R., Roy, J. H. B. and Smith, R. H. (1977). Proc. 2nd int. Symp. Protein Metabolism and Nutrition, Pudoc, Wagenigen p. 137.Google Scholar
Nugent, J. H. A. (1978). Studies on Proteolysis in the Rumen. PhD Thesis, University of Cambridge.Google Scholar
Nugent, J. H. A. & Mangan, J. L. (1978). Proc. Nutr. Soc. 37, 48A.Google Scholar
Reid, M. S. & Bieleski, R. L. (1968). Analyt. Biochem 22, 374.CrossRefGoogle Scholar
Roy, J. B. H., Balch, C. C., Miller, E. L., Orskov, E. R. & Smith, R. H. (1977). Proc. 2nd int. Symp. Protein Metabolism and Nutrition, Pudoc, Wagenigen p. 126.Google Scholar
Shafa, F. & Salton, M. R. J. (1960). J. gen. Microbiol. 22, 137.CrossRefGoogle Scholar