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Remethylation with dietary methyl donors contributes a significant proportion of methionine for the synthesis of protein and creatine in neonatal piglets (258.3)
Author(s) -
Robinson Jason,
McBreairty Laura,
Harding Scott,
Randell Edward,
Brunton Janet,
Bertolo Robert
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.258.3
Subject(s) - methionine , transmethylation , creatine , choline , medicine , amino acid , chemistry , phenylalanine , endocrinology , biochemistry , protein biosynthesis , betaine , de novo synthesis , biology , enzyme
Methionine is an essential amino acid that is in high demand in neonates for both protein synthesis and as the primary methyl donor for transmethylation (TM) reactions. The vast majority of methyl groups are used for synthesis of creatine (CR) and phosphatidylcholine (PC). The demethylated methionine can be remethylated by dietary methyl donors such as folate, choline and betaine, but to what extent is unclear. We hypothesized that these methyl donors provide a nutritionally significant proportion of available methionine for TM and protein synthesis. 4‐8 d old piglets were fed a diet devoid (n=8) or replete (n=7) of methyl donors at 80% of the methionine requirement; methionine and phenylalanine isotopes were infused to calculate flux to products. Whole body protein synthesis and breakdown were respectively, 15% (p<0.05) and 20% (p<0.04) lower during methyl deficiency, corresponding to a ~70% reduction in fractional protein synthesis (Ks) in muscle (p<0.03) and unchanged Ks in liver. Methyl deficiency also led to 25% lower hepatic TM to creatine (p<0.02), which was offset by a 2‐fold greater TM to PC (p<0.03), due to choline deficiency which increases PC synthesis via TM. In conclusion, dietary methyl donors can re‐synthesize a substantial proportion of methionine that is used primarily for protein synthesis and potentially growth. Grant Funding Source : Supported by CIHR