Repression of the formation of biosynthetic enzymes by the ultimate end product of their action has been shown to be an important aspect of metabolic regulation in microorganisms.1 In Escherichia coli and Salmonella typhimuwium each of the last four steps in the synthesis of valine and isoleucine is catalyzed by the same enzymes.2 Repression of these enzymes presents a unique situation since tw...

It is well established that impaired glucose metabolism is a frequent complication in patients with hepatic cirrhosis. We previously showed that leucine, one of the branched-chain amino acids (BCAA), promotes glucose uptake under insulin-free conditions in isolated skeletal muscle from normal rats. The aim of the present study was to evaluate the effects of BCAA on glucose metabolism in a rat m...

This study investigates the effects of three branched-chain amino acids (BCAA; valine, leucine, and isoleucine) on the in vitro ruminal fermentation of wheat straw using batch cultures of mixed ruminal microorganisms. BCAA were added to the buffered ruminal fluid at a concentration of 0, 2, 4, 7, or 10 mmol/L. After 72 h of anaerobic incubation, pH, volatile fatty acids (VFA), and ammonia nitro...

Bacterial adaptation involves extensive cellular reorganization. In particular, growth rate adjustments are associated with substantial modifications of gene expression and mRNA abundance. In this work we aimed to assess the role of mRNA degradation during such variations. A genome-wide transcriptomic-based method was used to determine mRNA half-lives. The model bacterium Lactococcus lactis was...

An experiment was conducted to investigate the effects of branched-chain amino acid (BCAA) interactions on their utilization by growing pigs and the effects of excessive amounts of BCAA (leucine, isoleucine, valine) on the utilization of methionine. A semipurified diet containing 100 g crude protein/kg with a balanced amino acid pattern was prepared using casein supplemented with free amino aci...

The metabolism of an essential amino acid, isoleucine, by human leukemic and gradient-separated normal human leukocytes of various types and maturity was studied. Blood leukocytes were isolated and incubated with [U-’4CJ isoleucine. Separation of metabolic intermediates was accomplished by sequential extraction. The rate of isoleucine incorporation into protein by immature cells from untreated ...

The metabolism of an essential amino acid, isoleucine, by human leukemic and gradient-separated normal human leukocytes of various types and maturity was studied. Blood leukocytes were isolated and incubated with [U-’4CJ isoleucine. Separation of metabolic intermediates was accomplished by sequential extraction. The rate of isoleucine incorporation into protein by immature cells from untreated ...