Essential role of adenosylcobalamin in leucine synthesis from beta-leucine in the domestic chicken
| Autor: | Nelson E. Ward, J. E. Jones, D. V. Maurice |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
Vitamin
medicine.medical_specialty Medicine (miscellaneous) Biology Kidney chemistry.chemical_compound Leucine Internal medicine medicine Animals Cyanocobalamin Vitamin B12 Amino Acids Intramolecular Transferases Poultry Diseases Transaminases Amino Acid Isomerases chemistry.chemical_classification Nutrition and Dietetics Methionine Kidney metabolism Vitamin B 12 Deficiency Adenosylcobalamin Amino acid Enzyme Activation Endocrinology chemistry Biochemistry Female Cobamides Chickens medicine.drug |
| Zdroj: | The Journal of nutrition. 118(2) |
| ISSN: | 0022-3166 |
| Popis: | This study was designed to investigate a postulated relationship between vitamin B-12 and leucine metabolism in mature domestic chickens. Plasma amino acid analysis revealed the presence of beta-leucine at a concentration of 60 to 80 mumol/l. After 425 d on a vitamin B-12-deficient diet, plasma beta-leucine was 133% higher (P less than 0.06) and plasma leucine and methionine lower (P less than 0.03) than values in plasma from hens fed a diet adequate in vitamin B-12. Branched-chain-amino-acid aminotransferase (EC 2.6.1.42) (BCAT) activity was not enhanced by vitamin B-12 deprivation (P greater than 0.05). In contrast to leucine, beta-leucine was not utilized as substrate by BCAT for the formation of alpha-ketoisocaproate. Kidney extracts possessed leucine 2,3-aminomutase (EC 5.4.3.7) (LAM) activity, as evidenced by enhanced conversion of beta-leucine to alpha-leucine in the presence of adenosylcobalamin. LAM activity could not be demonstrated in liver or muscle extract, while leucine formation by pancreas extract was negligible. These data represent the first evidence of the presence of the amino acid beta-leucine in chicken plasma. In addition, the data support vitamin B-12-dependent leucine synthesis from beta-leucine in the chicken and highlight the kidney's role in leucine synthesis. |
| Databáze: | OpenAIRE |
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