Topic
Lactate dehydrogenase
About: Lactate dehydrogenase is a research topic. Over the lifetime, 11477 publications have been published within this topic receiving 271496 citations. The topic is also known as: LDH & lactate dehydrogenase.
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TL;DR: The bearing of these findings on various problems, including the number of NAD(+)-NADH pools in liver cells; the applicability of the method to tissues other than liver; the transhydrogenase activity of glutamate dehydrogenase; the physiological significance of the difference of the redox states of mitochondria and cytoplasm; aspects of the regulation of theredox state of cell compartments; the steady-state concentration of mitochondrial oxaloacetate.
Abstract: 1. The concentrations of the oxidized and reduced substrates of the lactate-, β-hydroxybutyrate- and glutamate-dehydrogenase systems were measured in rat livers freeze-clamped as soon as possible after death. The substrates of these dehydrogenases are likely to be in equilibrium with free NAD+ and NADH, and the ratio of the free dinucleotides can be calculated from the measured concentrations of the substrates and the equilibrium constants (Holzer, Schultz & Lynen, 1956; Bucher & Klingenberg, 1958). The lactate-dehydrogenase system reflects the [NAD+]/[NADH] ratio in the cytoplasm, the β-hydroxybutyrate dehydrogenase that in the mitochondrial cristae and the glutamate dehydrogenase that in the mitochondrial matrix. 2. The equilibrium constants of lactate dehydrogenase (EC 1.1.1.27), β-hydroxybutyrate dehydrogenase (EC 1.1.1.30) and malate dehydrogenase (EC 1.1.1.37) were redetermined for near-physiological conditions (38°; I0·25). 3. The mean [NAD+]/[NADH] ratio of rat-liver cytoplasm was calculated as 725 (pH7·0) in well-fed rats, 528 in starved rats and 208 in alloxan-diabetic rats. 4. The [NAD+]/[NADH] ratio for the mitochondrial matrix and cristae gave virtually identical values in the same metabolic state. This indicates that β-hydroxybutyrate dehydrogenase and glutamate dehydrogenase share a common pool of dinucleotide. 5. The mean [NAD+]/[NADH] ratio within the liver mitochondria of well-fed rats was about 8. It fell to about 5 in starvation and rose to about 10 in alloxan-diabetes. 6. The [NAD+]/[NADH] ratios of cytoplasm and mitochondria are thus greatly different and do not necessarily move in parallel when the metabolic state of the liver changes. 7. The ratios found for the free dinucleotides differ greatly from those recorded for the total dinucleotides because much more NADH than NAD+ is protein-bound. 8. The bearing of these findings on various problems, including the following, is discussed: the number of NAD+–NADH pools in liver cells; the applicability of the method to tissues other than liver; the transhydrogenase activity of glutamate dehydrogenase; the physiological significance of the difference of the redox states of mitochondria and cytoplasm; aspects of the regulation of the redox state of cell compartments; the steady-state concentration of mitochondrial oxaloacetate; the relations between the redox state of cell compartments and ketosis.
1,671 citations
TL;DR: In this paper, a simple yet quantitative method for assessing glutamate mediated central neuronal cell injury in cortical cell culture has been proposed; the magnitude of LDH efflux in the cultures correlates in a linear fashion with the number of neurons damaged by glutamate exposure.
1,330 citations
TL;DR: This LDH release assay combines the advantages of reliability and simple evaluation characteristic of radioisotope release assays with the convenience of speed and avoidance of radioactivity and suggests that LDH releases are an appropriate and possibly preferable means of measuring cellular cytotoxic reactions.
1,316 citations
TL;DR: This chapter discusses the lactate dehydrogenase, the only simpler dehydrogen enzyme where both structure and sequence are known at present.
Abstract: Publisher Summary This chapter discusses the lactate dehydrogenase. Lactic acid is the end product of anaerobic glycolysis in muscle tissue has been known for all of this century. Cell-free extracts able to catalyze the oxidation of lactate to pyruvate. The five different permutations of two different polypeptide chains readily explained the electrophoretic patterns. The distribution of these two polypeptide chains was dependent on whether the extract originated in aerobic tissue, such as heart or in anaerobic tissue as in skeletal muscle. The NAD + binding structure found in L-lactate dehydrogenase (LDH) occurs frequently in other dehydrogenases and other proteins. In LDH the problem of catalysis is presented in stark simplicity. The complications of metal ions, linked substrate phosphorylation, or of ammonia uptake are absent. LDH is the only simpler dehydrogenase where both structure and sequence are known at present. The concept of multiple molecular forms of LDH has stimulated many investigations into the nature, function, and control of isozymes. There are only two major structural genes and there is a complex variety of other LDH genes, which can be expressed in some tissues at certain stages of development.
1,242 citations
TL;DR: Evidence of an active linkage between the human genes that control lactate dehydrogenase B and peptidase B is presented, but it is concluded that there is no link between the genes for lactate dehydration A and lactatehydrogenase A.
Abstract: Evidence of an active linkage between the human genes that control lactate dehydrogenase B and peptidase B is presented. It is also concluded that there is no link between the genes for lactate dehydrogenase A and lactate dehydrogenase B.
1,145 citations