Biochemical changes in kidneys of normal and stone forming rats with L(+)-tartrate

Influence of L(+)-tartrate was studied on certain enzymes, protein bound carbohydrates and lipids in the renal tissues of experimentally induced stone forming rats. The elevation in kidney LDH was moderate in the stone forming groups while tartrate had no effect. The significant increases in the activities of (Na+, K+)- and (Ca2+)-ATPases in the calculogenic group was lowered to that of normal level with tartrate administration. Acid phosphatase activity was significantly lowered in the tartrate treated groups. The significant reduction in phospholipids and elevation in sialic acid levels during stone formation are suggestive of minor alterations in the cellular structure. The changes in the transport ATPases is likely to affect the transport mechanism of nutrients and ions.     

药用谷氨酸含量测定方法的改进

药用谷氨酸是具有生物活性的L-型谷氨酸。中国药典(1977年版)只对它的旋光度做了如下规定:(+)31.7～(+)32.3,而对其含量限度未做要求。据查英、美药典(1980年版)、日本药局方第十版对该药均无收载。因此我们做了一些工作。采用几种不同方法测定药用谷氨酸的含量,对凯氏定氮法、中和法、旋光法进行了比较。测定中以凯氏定氮法为准,计算回收率,并计算其均值、标准差及变异系数。实验结果表明,采用旋光法较好。回收率为100.003%,标准差为0.2525,变异系数为0.2525%。     

Characterization of the fructose 1,6-bisphosphate-activated, L(+)-lactate dehydrogenase from Thermoanaerobacter ethanolicus.

The L(+)-lactate dehydrogenase from Thermoanaerobacter ethanolicus wt was purified to a final specific activity of 598 mumol pyruvate reduced per min per mg of protein. The specific activity of the pure enzyme with L(+)-lactate was 0.79 units per mg of protein. The M(r) of the native enzyme was 134,000 containing a single subunit type of M(r) 33,500 indicating an apparent tetrameric structure. The L(+)-lactate dehydrogenase was activated by fructose 1,6-bisphosphate in a cooperative manner affecting Vmax and Km values. The activity of the enzyme was also effected by pH, pyruvate and NADH. The Km for NADH at pH 6.0 was 0.05 mM and the Vmax for pyruvate reduction at pH 6.0 was 1082 units per mg in the presence of 1 mM fructose 1,6-bisphosphate. The enzyme was inhibited by NADPH, displaying an uncompetitive pattern. This pattern indicated that NADPH was a negative modifier of the enzyme. The role of L(+)-lactate dehydrogenase in controlling the end products of fermentation is discussed.     

The effects of acute and chronic nicotine hydrogen (+)-tartrate administration and subsequent withdrawal on rat liver tryptophan pyrrolase activity and their comparison with those of morphine, phenobarbitone and ethanol.

Acute administration of nicotine hydrogen (+)-tartrate enhances the activity of rat liver tryptophan pyrrolase by a hormonal mechanism. Chronic nicotine treatment inhibits, and subsequent withdrawal enhances, the pyrrolase activity. The inhibition during chronic treatment is not due to a defective apoenzyme synthesis nor a decreased cofactor availability. Regeneration of liver NADP+ in vitro and in vivo reverses the inhibition. Chronic nicotine administration increases the liver NADPH concentration. The above effects of nicotine resemble to a remarkable degree those previously shown for morphine, phenobarbitone and ethanol. All effects are compared, and their possible significance in relation to drug dependence is discussed.     

不同的中和剂对L(+)-乳酸发酵的影响

分别利用CaCO3、6 mol/L氨水和6 mol/L NaOH溶液调控乳酸发酵过程的pH,得到的乳酸浓度为169.1g/L、187.9g/L和170.1g/L(以发酵液的初始体积计算),分别是无pH调控发酵过程的4.9倍、5.4倍和4.9倍;得到的OD620分别为19.3、21.6和16.4,分别是无pH调控(OD620为8.5)的2.3倍、2.5倍和1.9倍.相对于氨水和NaOH来说,CaCO3粉末是一种缓慢型的酸中和剂,pH调节能力有限,只能将pH维持在4.9～5.2.但CaCO3可以将乳酸以生成乳酸钙的形式沉淀下来,给下游乳酸的分离提取带来一定的方便.因此对于传统的分批式发酵,CaCO3仍不失为一种较好的选择.氨水和NaOH溶液都可以很好地将发酵液的pH调控在6.0,其中氨水是一种最理想的酸中和剂,既有利于乳酸的生物合成又能促进乳酸菌的生长.     

L(+)-Lactate binding to preparations of rat hepatocyte plasma membranes

Incubation of rat hepatocyte plasma membranes with L-[14C]lactate resulted in the labeling of protein(s) of apparent molecular weight 40,000 when examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The binding was saturable, irreversible, and inhibited by pyruvate, 2-oxoglutarate, and alpha-cyano-3-hydroxycinnamate, but not by D-lactate. It was markedly enhanced by L-alanine, but not D-alanine or beta-alanine. The binding protein(s) could be solubilized in cholic acid giving a single peak on gel filtration corresponding to a molecular weight of 26,000 and an isoelectric point of 5.1. This peak, when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, ran in a position corresponding to an apparent molecular weight of 40,000. When membranes were treated with Triton X-100, lactate binding was retained by the Triton-insoluble fraction. The binding of L-[14C]lactate increased with incubation time, due apparently to the appearance of new binding sites and not to sequestration into vesicles. As many of the characteristics of lactate binding to rat hepatocyte plasma membranes were found to be similar to those of lactate entry into isolated hepatocytes, we speculate that the lactate-binding protein could represent part or whole of a plasma-membrane lactate transporter. Lactate-binding proteins of the same molecular weight were identified in the plasma membranes from rat erythrocytes, cardiac muscle, skeletal muscle, lung, and brain.     

Direct fermentation of corn to L(+)-lactic acid byRhizopus oryzae

Summary Rhizopus oryzae NRRL 395 was found capable of fermenting ground corn directly to L(+)-lactic acid in the presence of calcium carbonate. The average yield of L(+)-lactic acid was more than 44% on the basis of the amount of total carbohydrate as glucose consumed.     

Optimization of L(+)-lactic acid production employing statistical experimental design

Summary An orthogonal 2³-factorial experimental design was used to optimize L(+)-lactic acid production byLactobacillus casei. With a 22 % (v/v) inoculum the optimum concentration of yeast extract for maximum lactic acid concentration and yield was about 2 % (w/v) and that of the initial glucose 9 to 11 %.     

Synthesis of (+)-Turmeronol A,an Inhibitor of Soybean Lipoxygenase,and (+)-ar-Turmerone

Syntheses of optically pure turmeronol A and turmerone were achieved in a simple manner starting from ethyl (R)-3-hydroxybutanoate (4) of 100% e.e. The key step was the displacement of the chiral tosylate (6) with an organocopper reagent.     

Preparation of L (+) beta-hydroxyisobutyric acid by bacterial oxidation of isobutyric acid

A process for the bacterial oxidation of isobutyric acid to L(+) β-hydroxyisobutyric acid has been developed. The strain of Pseudomonas putida (ATCC 21244) used in this fermentation was isolated from local soil. The process was carried out in a 15-liter fermentor over a period of 70 hr and produced L(+) β-hydroxyisobutyric acid in conversions as high as 48%. Hydroxylation of the methyl group of isobutyric acid has special interest because it is difficult to perform chemically. The useful chemical syntheses of β-hydroxyisobutyric acid available at present do not start with isobutyric acid and are not stereospecific.