Lactic dehydrogenase and metabolism of human leukocytes in vitro

During transformation and division of lymphocytes in culture, the lactic dehydrogenase isozymes migrate increasingly toward the cathode. With extension of the time in culture, the mitotic index declines, and the isozyme pattern reverts to dominance of those bands that move toward the anode, despite the cellular tendency to anaerobic metabolism. These findings suggest that synthesis of the more slowly migrating lactic dehydrogenase isozymes in this system is related to mitotic activity, and not to the aerobic or anaerobic conditions of cell culture.     

柠檬醛对黄曲霉细胞内两个氧化还原酶的影响

柠檬醛（citral）是单萜类小分子芳香醛，研究发现它能有效地抑制黄曲霉细胞内苹果酸脱氢酶和琥珀酸脱氢酶2种酶的活力，其中苹果酸脱氢酶的活力降低了29．2％（以NADP^ 为辅酸）和23．8％（以NAD^ 为辅酶），琥珀酸脱氢酶的活力降低了27．1％。     

MOLECULAR HETEROGENEITY OF ENZYMES: MALATE DEHYDROGENASE OF EUGLENA

Experiments with analogs of the coenzyme nicotinamide adenine dinucleotide demonstrate that the molecular forms of malate dehydrogenase in Euglena vary with the nutritional environment. Electrophoretic separations on starch gel show that Euglena grown on autotrophic medium has a malate dehydrogenase which is lacking in Euglena grown on heterotrophic medium.     

Enzyme-coenzyme complexes of pyridine nucleotide-linked dehydrogenases

Enzyme-reduced coenzyme binary complexes produce previously unreported shifts in the spectrum of the free coenzyme. These shifts give rise to difference spectra which resemble a general environmental change for reduced diphosphopyridine nucleotide (DPNH) in the glutamic dehydrogenase-DPNH complex, and indicate a more specific enzyme-coenzyme interaction for yeast alcohol dehydrogenase-DPNH, isocitrate dehydrogenase-TPNH, and lactic dehydrogenase-DPNH complexes.     

鱿鱼MUCIN型糖蛋白抗疲劳作用试验研究

为评价鱿鱼M UCIN型糖蛋白的抗疲劳作用,分别以不同剂量的鱿鱼M UCIN型糖蛋白经口给予昆明小鼠连续灌胃4周,研究鱿鱼MUCIN型糖蛋白对小鼠负重力竭游泳时间,肝糖原（LC）、血糖（GLU）、血乳酸（LD）含量和血乳酸脱氢酶（LDH）活性等反映疲劳的生化指标的影响。结果表明,与对照组相比,中、高剂量组能明显延长小鼠力竭游泳时间;增加运动后小鼠LC的储备量和GLU含量,增强LDH的活性,降低LD的含量,减少乳酸在肌肉及血液中的堆积,延缓疲劳的发生。说明鱿鱼M UCIN型糖蛋白对小鼠具有较好的抗疲劳作用。     

Serial Lactic Dehydrogenase Activity in Plasma of Mice with Growing or Regressing Tumors

Close correlation has been observed between the serially tested plasma level of a glycolytic enzyme, lactic dehydrogenase, and the growth of several transplanted mouse tumors. The character of the lactic dehydrogenase curve determined by serial blood sampling of the animals during the development of such tumors is found to consist of five separate phases. The first three appear before any visible evidence of tumor growth. Inhibition or regression of tested tumors, induced by therapeutic compounds, was accurately reflected in a corresponding reduction of lactic dehydrogenase activity in the peripheral plasma of the host.     

Transmissible agent associated with some mouse neoplasms

The association between some forms of murine cancer and an agent that increases the lactic dehydrogenase activity in the plasma of normal mice is confirmed. This agent, however, is not associated with all mouse neoplasms.     

Dehydrogenase Activities in Dystrophic Mice

The levels of activity of glucose-6-phosphate dehydrogenase, isocitric dehydrogenase, glutathione reductase, lactic dehydrogenase, and a-glycerophosphate dehydrogenase have been studied in the gastrocnemius muscle of mice with "dystrophia muscularis." The activity of enzymes requiring triphosphopyridine nucleotide as a cofactor is increased relative to the control littermates, whereas the activity of those enzymes requiring diphosphopyridine nucleotide is decreased.     

Transmissible Agent Associated with 26 Types of Experimental Mouse Neoplasms

A transmissible agent or factor has been found to be associated with all transplanted and spontaneous experimental tumors examined. This observation was made possible by utilization of a biochemical response of normal animals when inoculated with plasma or organ extracts from tumor-bearing hosts. This transmissible enzymic "lesion" is expressed by a five- to tenfold increase in the plasma lactic dehydrogenase activity of the injected normal test animals. The factor is heat labile, passes through bacteria-retaining filters, but is nondialyzable. It is partially sedimented by centrifugation at 100,000g for 1 hour.     

Inhibiting effect of tobacco smoke on some crystalline enzymes

Tobacco smoke absorbed in phosphate buffer at neutral pH inhibits irreversibly the enzymes rabbit muscle glyceraldehyde-3-phosphate dehydrogenase and yeast alcohol dehydrogenase, whereas lactic dehydrogenase and glutamic dehydrogenase are not inhibited. A transient inhibition of beef liver catalase occurs. Indirect evidence suggests that the observed enzyme inhibition is caused by peroxides present in the smoke.     

不同类型大豆同工酶的研究

本文系用聚丙烯酰胺凝胶垂直平板电泳方法对不同纬度的野生、半野生及栽培大豆的苹果酸脱氢酶、酸性磷酸酯酶同工酶进行了研究,提出大豆同工酶模式酶谱。G.soja 亚属大豆苹果酸脱氢酶共有6条酶带,酸性磷酸酯酶共有12条酶带。所有材料都出现苹果酸脱氢酶Ⅳ带,反映了遗传的同源性,并可作为 G.soja 亚属大豆的共同酶带。种间酶带出现频率和相对含量分析表明,半野生大豆处于野生大豆和栽培大豆中间,栽培大豆系由野生大豆经过中间类型进化而来。在进化过程中既有原酶带缺失又有新酶带产生,苹果酸脱氢酶Ⅳ带,酸性磷酸酯酶Ⅶ、Ⅷ、Ⅸ带平均相对含量在30°—35°N 最高,说明与地理分布有关。     

LACTIC DEHYDROGENASE: GENETIC CONTROL IN MAN

A genetically determined variant of lactic dehydrogenase has been observed in the red cells of four members of two generations of a Brazilian family. The appearance of the variant after starch-gel electrophoresis of the hemolysates supports the concept that the lactic dehydrogenase isozymes are determined by the interaction of two subunits which are under separate genetic control. The products of the mutant and normal allele do not, however, appear to associate randomly to form isozymes. The similarity of the relative retardation of normal and mutant isozymes in gels made with increasing concentrations of starch suggests that they do not differ significantly in size.     

Autosomal phosphogluconic dehydrogenase polymorphism in the cat (Felis catus L.)

Three patterns of 6-phosphogluconic dehydrogenase activity were obtained by starch-gel electrophoresis of blood from domestic cats. Genetic analysis indicates control of these patterns by a pair of alleles at an autosomal locus. Presence of three enzymatically active bands in heterozygotes and of single bands in homozygotes is compatible with at least a dimeric structure for the enzyme.     

Cytochrome c reductase of tri- and diphosphopyridine nucleotides in rat lens

The ocular lens of the 28- to 32-day-old rat contains an active hexose monophosphate shunt pathway for the combustion of glucose. Triphosphopyridine nucleotide (TPNH) cytochrome c reductase is present in this organ and is approximately one-third more active than diphosphopyridine nucleotide (DPNH) cytochrome c reductase. Since there is no transhydrogenase activity in these lenses, and since DPNH lactic dehydrogenase is 15 times as active as TPNH lactic dehydrogenase, the presence of an active TPNH cytochrome c reductase may provide this organ with the means of reoxidizing the relatively large amounts of TPNH formed by the direct oxidative pathway of glucose metabolism. Although TPNH oxidation in other tissues has not as yet been shown to yield adenosine triphosphate (ATP) directly, it is possible that such a mechanism may be operative in the rat lens.     

葱莲的同工酶和染色体核型分析

本文报道了对葱莲[Zephyranthes candida(Lindl.)Herb.]的过氧化物酶,酯酶,乙醇脱氢酶和6-磷酸-葡萄糖脱氢酶等同工酶的研究和对葱莲的体细胞染色体数目及其核型所进行的分析。结果表明,葱莲的过氧化物酶同工酶呈现出6条分子量相对较大的谱带;酯酶同工酶可划分成2个活性区,共10条酶带;乙醇脱氢酶同工酶只有1条酶带;6-磷酸-葡萄糖脱氢酶同工酶有4条酶带,可划分成3个活性区。该种核型为2n=28=20m+2m(SAT)+6sm,核型的不对称性为 Stebbins 核型分类的2B 型,具有核型的杂合性。染色体数目为2n=28,与前人报道不一致。     

Direct demonstration of an adaptive constraint

The role of constraint in adaptive evolution is an open question. Directed evolution of an engineered beta-isopropylmalate dehydrogenase (IMDH), with coenzyme specificity switched from nicotinamide adenine dinucleotide (NAD) to nicotinamide adenine dinucleotide phosphate (NADP), always produces mutants with lower affinities for NADP. This result is the correlated response to selection for relief from inhibition by NADPH (the reduced form of NADP) expected of an adaptive landscape subject to three enzymatic constraints: an upper limit to the rate of maximum turnover (kcat), a correlation in NADP and NADPH affinities, and a trade-off between NAD and NADP usage. Two additional constraints, high intracellular NADPH abundance and the cost of compensatory protein synthesis, have ensured the conserved use of NAD by IMDH throughout evolution. Our results show that selective mechanisms and evolutionary constraints are to be understood in terms of underlying adaptive landscapes.     

D(-)-lactate dehydrogenase in lower fungi

A lactate dehydrogenase, specific for nicotinamide-adenine dinucleotide and D(-)-lactate, has been detected in extracts from two fungi of the order Leptomitales (Oomycetes). Several fungi of this order carry out a lactic acid fermentation under conditions of reduced oxygen tension.     

非离子态NH3和Hg2+对草鱼免疫血清及前肾的LDH与G6PDH的影响

运用同工酶分析技术 ,发现 NH3 对草鱼的 LDH表达的影响主要为前肾 ,表现为 B基因表达较多或其酶活性变化 ;它同时也使 G6 PDH的条带减少 ;Hg2 对前肾 LDH的影响则主要表现为 L DH1与LDH2 ,而使 G6 PDH的酶带从 12条减少为血清的 8条和前肾的 9条 ,表明 NH3 和 Hg2 污染对同工酶酶基因表达具有一定程度的抑制效应     

猪的血清酶活力与其耐热、耐粗饲性能关系的研究

本试验研究了大约克夏猪的磷酸肌酸激酶(CPK)、乳酸脱氢酶(LDH)和碱性磷酸酶(AKP)与其耐热、耐粗饲性能的关系,探讨了血清酶活力在猪的生产和育种中的应用。结果表明:这三种血清酶有较强的稳定性,且对逆境中的大约克夏猪有较强的耐热、耐粗饲性,生产性能表现也良好,可考虑选择应用于生产和育种。