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http://crossmark.crossref.org/dialog/?doi=10.1007/s00394-015-1049-0&domain=pdf
Web End = Eur J Nutr (2016) 55:24232430 DOI 10.1007/s00394-015-1049-0
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http://crossmark.crossref.org/dialog/?doi=10.1007/s00394-015-1049-0&domain=pdf
Web End = Betaine is as effective as folate at resynthesizing methionine for protein synthesis during moderate methionine deciency in piglets
Laura E. McBreairty1 Jason L. Robinson1 Scott V. Harding2 Edward W. Randell1,3 Janet A. Brunton1 Robert F. Bertolo1
Abstract
Purpose Both folate and betaine (synthesized from cho-line) are nutrients used to methylate homocysteine to reform the amino acid methionine following donation of its methyl group; however, it is unclear whether both remethylation pathways are of equal importance during the neonatal period when remethylation rates are high. Methionine is an indispensable amino acid that is in high demand in neonates not only for protein synthesis, but is also particularly important for transmethylation reactions, such as creatine and phosphatidylcholine synthesis. The objective of this study was to determine whether supplementation with folate, betaine, or a combination of both can equally re-synthesize methionine for protein synthesis when dietary methionine is limiting.
Methods Piglets were fed a low methionine diet devoid of folate, choline, and betaine, and on day 6, piglets were supplemented with either folate, betaine, or folate + betaine
(n = 6 per treatment) until day 10. [1-13C]-phenylalanine
oxidation was measured as an indicator of methionine availability for protein synthesis both before and after 2 days of supplementation.
Results Prior to supplementation, piglets had lower concentrations of plasma folate, betaine, and choline compared to baseline with no change in homocysteine.
Received: 5 July 2015 / Accepted: 16 September 2015 / Published online: 29 September 2015 Springer-Verlag Berlin Heidelberg 2015
Post-supplementation, phenylalanine oxidation levels were 2046 % lower with any methyl donor supplementation (P = 0.006) with no difference among different supple
mentation groups. Furthermore, both methyl donors led to similarly lower concentrations of homocysteine following supplementation (P < 0.05).
Conclusions These data demonstrate an equal capacity for betaine and folate to remethylate methionine for protein synthesis, as indicated by lower phenylalanine oxidation.
Keywords Piglet Folate Betaine Protein synthesis 1-Carbon metabolism
Introduction
The amino acid methionine is important in the neonate not only for protein synthesis and growth, but once adenylated to S-adenosylmethionine (SAM) is also the universal methyl donor in over 50 transmethylation reactions [1].The availability of methionine for its various functions...