d-Amino acids are now recognized to be widely present in mammals. Renal d-amino-acid oxidase (DAO) is associated with conversion of d-amino acids to the corresponding alpha-keto acids, but its contribution in vivo is poorly understood because the alpha-keto acids and/or l-amino acids formed are indistinguishable from endogenous compounds. First, we examined whether DAO is indispensable for conv...

Diamond-Blackfan anemia (DBA; OMIM:105650) attracts much attention, because symptoms are associated with mutations in RPS19 and RPS24 in 25% and 2% of DBA patients, respectively, indicating a possible relationship between the ribosomal function, translation levels and erythropoiesis. Indeed, in our recent study we showed that translational efficiency was lowered in most DBA patients, and leucin...

Until recently, essentially all of our information concerning the biosynthesis of leucine stemmed from experiments with CY4labeled intermediates. Ehrensvard et al. (l), in experiments with yeast grown on C4-labeled acetate as the sole carbon source, showed that the carboxyl carbon of leucine is probably derived from the carboxyl of acetic acid. In isotopic competition experiments, Abelson and V...

1. To investigate the effects of starvation, elective surgery, accidental injury and other clinical conditions on the metabolism of branched-chain amino acids in man, we have measured the basal concentration of leucine and the removal of metabolic effects of infused L-leucine. 2. The blood concentration of leucine as significantly increased by surgery, starvation and accidental injury, and decr...

The leucine analogue 5',5',5',-trifluoroleucine (fluoroleucine) replaced leucine for repression of the isoleucine-valine biosynthetic enzymes in Salmonella typhimurium. In contrast, the analogue had no effect on derepression of the leucine biosynthetic enzymes in leucine auxotrophs grown on limiting amounts of leucine. The effect of fluoroleucine on repression appeared to be specific for leucin...

W\e have reported previously that the oral or intravenous administration of the amino acid l-leucine to healthy subjects results in increases in plasma insulin and decreases in blood glucose and plasma free fatty acids (2, 3). After the administration of leucine to healthy subjects pretreated with either chlorpropamide or tolbutamide (2, 3), and also to some patients with functioning islet cell...

The effects of leucine, its metabolites, and the 2-oxo acids of valine and isoleucine on protein synthesis and degradation in incubated limb muscles of immature and adult rats were tested. Leucine stimulated protein synthesis but did not reduce proteolysis when leucine transamination was inhibited. 4-Methyl-2-oxopentanoate at concentrations as low as 0.25 mM inhibited protein degradation but di...

Whole body leucine kinetics was compared in endurance-trained athletes and sedentary controls matched for age, gender, and body weight. Kinetic studies were performed during 3 h of rest, 1 h of exercise (50% maximal oxygen consumption), and 2 h of recovery. When leucine kinetics were expressed both per unit of body weight and per unit of fat-free mass, both groups demonstrated an increase in le...

The stimulatory effect of an inward H+ gradient on the Na+-independent L-leucine uptake by the plasma membrane vesicles from Chang liver cells (Mohri, T., Mitsumoto, Y., and Ohyashiki, T. (1983) Biochem. Int. 7, 159-167) has been shown to be due to the increase of the Km value without changing the Vmax value in the transport kinetics. The uptake of leucine by the vesicles is accompanied by intr...

Leucine has been shown to stimulate adipose tissue protein synthesis in vivo as well as leptin secretion, protein synthesis, hyper-plastic growth, and tissue morphogenesis in in vitro experiments using freshly isolated adipocytes. Recently, others have proposed that leucine oxidation in the mitochondria may be required to activate the mammalian target of rapamycin (mTOR), the cytosolic Ser/Thr ...