Escherichia coli leu(+) episomes were transferred to Salmonella typhimurium. The levels of two leucine-forming enzymes were normal (low) in the resulting merodiploids, suggesting that the putative Samonella leucine repressor recognizes the Escherichia leucine operator.

Adipose tissue from fed rats rapidly degrades [l14C]leucine to 14C02. This process is stimulated by glucose (but not by pyruvate) and by insulin, which also enhances the degradation of isoleucine and valine. Fasting and protein deficiency markedly reduced the catabolism of [l-‘4C]leucine in epididymal fat pads by decreasing the decarboxylation of a-ketoisocaproic acid and the transamination of ...

The initial step in the fermentation of leucine to acetate, isobutyrate, and ammonia by Clostridium sporogenes is the B12 coenzyme-dependent conversion of alpha-leucine to beta-leucine (3-amino-4-methylpentanoate). The amino group migration reaction, catalyzed by leucine 2,3-aminomutase, is reversible and is inhibited by intrinsic factor. The enzyme activity has been found in several clostridia...

To study the effect of insulin on leucine kinetics, three groups of conscious dogs were studied after an overnight fast (16-18 h). One, saline-infused group (n = 5), served as control. The other two groups were infused with somatostatin and constant replacement amount of glucagon; one group (n = 6) received no insulin replacement, to produce acute insulin deficiency, and the other (n = 6) was c...

Leucine has profound effects on glucose metabolism in muscle; however, the effects of leucine on glucose transport in muscle have not been well documented. We investigated the effects of leucine on contraction- and insulin-stimulated glucose transport in isolated rat epitrochlearis muscle in vitro. In the absence of insulin, tetanic contraction increased 3-O-methyl-D-glucose (3-MG) transport an...

The available findings concerning the association between branched-chain amino acids (BCAAs)-particularly leucine-and insulin resistance are conflicting. BCAAs have been proposed to elicit different or even opposite effects, depending on the prevalence of catabolic and anabolic states. We tested the hypothesis that leucine supplementation may exert different effects at different stages of insul...

ODESSEY, RICHARD, AND ALFRED L. GOLDBERG. Oxidation of leucine by rat skeletal muscle. Am. J. Physiol. 223(6) : 1376-1383. 1972.-In the isolated rat diaphragm, 14C02 production from L-leucine-1 -14C occurred at 86 y0 of the rate of its incorporation into protein. Experiments with L-leucine-U-14C indicate complete oxidation of leucine under these conditions. 14C02 production from leucine-1-14C w...

1. There are two saturable transport processes in the monkey small intestine for glycyl-L-leucine, one with Vmax. 1 mumol min-1 g-1 wet weight of tissue and an affinity constant (kt) of 5 mmol/l, and the other with Vmax 3.9 mumol min-1 g-1 wet weight of tissue and kt 33 mmol/l. 2. Glycyl-L-leucine uptake is inhibited by a wide variety of amino acids, although to a variable extent. The inhibitio...

We present a joint experimental-computational study to quantitatively describe the thermodynamics of hydrophobic leucine amino acids in aqueous solution. X-ray scattering data were acquired at a series of solute and salt concentrations to effectively measure interleucine interactions, indicating that a major scattering peak is observed consistently at q = 0.83 Å-1. Atomistic molecular dynamics ...