Oils with a high DAG (1,3-DAG) content have attracted considerable attention as a healthful food oil component. In this study, we report on the synthesis of 1,3-DAG from a mixture of FA, constituted largely of oleic and linoleic acids, using an immobilized 1,3-regioselective lipase from Rhizomucor miehei in a solvent-free system. The kinetics of 1,3-DAG production from FA and glycerol were investigated on the basis of a simplified model, taking into consideration the acyl migration reaction, the removal of water, and glycerol dissolution in the oil phase in addition to the esterification reactions. Both the yield of 1,3-DAG and the purity of DAG were evaluated under a variety of experimental conditions, including reaction temperature, pressure, and amount of enzyme present. When either the reaction temperature or the amount of enzyme used was increased, the 1,3-DAG production rate increased, but yield remained relatively constant. The 1,3-DAG yield as well as the purity of DAG gradually decreased because of the enhancement of acyl migration at later stages of the reaction after the 1,3-DAG concentration reached a maximum. Vacuum was important for attaining high yields of 1,3-DAG. Under conditions of a high vacuum (1 mm Hg) at 50°C, 1.09 M 1,3-DAG was produced from 1.29 M glycerol and 2.59 M FA in an 84% yield and in 90% purity.Rate constants k 1 = 7.50 × 10 −4 (L/mol/s) k 3 = 2.91 × 10 −4 (L/mol/s) k 5 = 7.85 × 10 −6 (1/s) k 7 = 1.84 × 10 −3 (L/mol/s) k 9 = 3.59 × 10 −4 (1/s) k 10 = 1.20 × 10 −2 (1/s)

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SummaryThe effects of a diet supplemented with branched-chain amino acids (BCAA; 4.8% or 6.2%) on BCAA catabolism and glycogen metabolism in rats were examined. Rats were fed a BCAA diet or control diet for 4 wk and part of the rats were subjected to exercise training during the experimental period. Feeding the BCAA diet increased serum BCAA concentrations and activity of the hepatic branched-chain a-keto acid dehydrogenase com plex, the rate-limiting enzyme in the catabolism of BCAA, suggesting that dietary BCAA promotes BCAA catabolism. Although the serum glucose concentration and glycogen con tents in the liver and gastrocnemius muscle of rested rats were not significantly affected by feeding of the BCAA diet, those in rats exhausted by acute exercise were 2-4-fold higher in rats fed the BCAA diet than in rats fed the control diet. The activity of pyruvate dehydrogenase complex in the liver and gastrocnemius muscle after acute exercise showed reverse trends; the complex activities (especially in liver) tended to be less in the BCAA diet group than in the control diet group. These results suggest that dietary BCAA spares glycogen stores in liver and skeletal muscle during exercise and that the decrease in pyruvate dehydrogenase complex activity in these tissues by dietary BCAA is involved in the mechanisms. Key Words branched-chain amino acids, glycogen, pyruvate dehydrogenase complex, rat liver, rat skeletal muscle Exercise enhances the protein metabolism in animals (1). The amino acid oxidation promoted by exercise could supply a significant fraction of the energy expen diture increased by exercise. Many researchers pay at tention to branched-chain amino acids (BCAA; leucine, isoleucine, and valine) because they comprise a signifi cantly large amount of indispensable amino acids in muscle proteins and food supplies (2), and leucine has been shown to inhibit protein degradation, stimulate protein synthesis, and promote insulin release from the pancreas (3). It has been shown that BCAA oxidation is greatly increased by exercise or electrical stimulation elicited muscle contraction in humans and rats (4-8).The effect of BCAA administration on endurance ex ercise performance was examined in humans and rats. It was reported that BCAA administration prolonged the exercise duration in humans during heat stress and in rats under normal conditions (9, 10), although there is a report that BCAA administration did not alter exer cise performance in humans under normal conditions (11). It has been well-known that the glycogen content in the liver and muscle is an important factor for deter mining the ability of prolonged physical performance (12). These findings suggest that BCAA administration might affect the glycogen metabolism in animals, re sulting in improving prolonged physical performance.The effects of BCAA administration on exercise per formance and energy metabolism are usually examined by the administration of a single dose of BCAA prior to exercise (9-11). However, it has been known that there is an adaptive...

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