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Atasoglu C, Guliye AY, Wallace RJ. Use of stable isotopes to measurede novosynthesis and turnover of amino acid-C and -N in mixed micro-organisms from the sheep rumenin vitro. Br J Nutr 2007; 91:253-62. [PMID: 14756911 DOI: 10.1079/bjn20031040] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Protein synthesis and turnover in ruminal micro-organisms were assessed by stable-isotope methods in order to follow independently the fate of amino acid (AA)-C and -N in different AA. Rumen fluid taken from sheep receiving a grass hay–concentrate diet were strained and incubatedin vitrowith starch–cellobiose–xylose in the presence of NH3and 5 g algal protein hydrolysate (APH)/l, in incubations where the labels were15NH3, [15N]APH or [13C]APH. Total15N incorporation was calculated from separate incubations with15NH3and [15N]APH, and net N synthesis from the increase in AA in protein-bound material. The large difference between total and net AA synthesis indicated that substantial turnover of microbial protein occurred, averaging 3·5 %/h. Soluble AA-N was incorporated on average more extensively than soluble AA-C (70v.50 % respectively,P=0·001); however, incorporation of individual AA varied. Ninety percent of phenylalanine-C was derived from the C-skeleton of soluble AA, whereas the incorporation of phenylalanine-N was 72 %. In contrast, only 15 % aspartate-C + asparagine-C was incorporated, while 45 % aspartate-N+asparagine-N was incorporated. Deconvolution analysis of mass spectra indicated substantial exchange of carboxyl groups in several AA before incorporation and a condensation of unidentified C2and C4intermediates during isoleucine metabolism. The present results demonstrate that differential labelling with stable isotopes is a way in which fluxes of AA synthesis and degradation, their biosynthetic routes, and separate fates of AA-C and -N can be determined in a mixed microbial population.
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Affiliation(s)
- C Atasoglu
- Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB, Scotland, UK
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KHAN RI, ANDO S, TAKAHASHI T, MORITA T, ONODERA R. In vitro metabolism of tyrosine by rumen bacteria, protozoa and their mixture. Anim Sci J 2003. [DOI: 10.1046/j.1344-3941.2003.00120.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chiral high-performance liquid chromatographic separation of the three stereoisomers of 2,6-diaminopimelic acid without derivatisation. J Chromatogr A 1993. [DOI: 10.1016/0021-9673(93)83192-u] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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