Dehydrase Activity Research Articles

Enzymatic Techniques for the Study of Pathways of Carbohydrate Utilization in the Rumen1

Enzymatic techniques were used to study the metabolism of carbohydrates by ruminal bacteria. A direct relationship was observed between the proportions of acetate and propionate formed and the specific activities of the enzymes which participate in forming these acids. An inverse relationship between butyrate formation and butyrate-forming enzymes was observed. The relative activities of succinic dehydrogenase to fumaric reductase, nicotinamide adenine dinucleotide-linked glutamic dehydrogenase to nicotinamide adenine dinucleotide phosphate-linked glutamic dehydrogenase, and pyridine nucleotide-nonlinked lactic dehydrogenase to pyridine nucleotide-linked lactic dehydrogenase were affected by the level of concentrates in the diet. Lactyl coenzyme A dehydrase activity was below the limits of the assay technique in many samples from the alfalfa hay diet, and increased to relatively high levels when concentrates were fed. It is suggested that the enzymatic method will prove valuable for studying the contributions of individual microorganisms to the overall ruminal metabolism, and, with certain limitations, useful for estimating the relative contributions of alternate pathways.

Enzymatic Techniques for the Study of Pathways of Carbohydrate Utilization in the Rumen

Enzymatic techniques were used to study the metabolism of carbohydrates by ruminal bacteria. A direct relationship was observed between the proportions of acetate and propionate formed and the specific activities of the enzymes which participate in forming these acids. An inverse relationship between butyrate formation and butyrate-forming enzymes was observed. The relative activities of succinic dehydrogenase to fumaric reductase, nicotinamide adenine dinucleotide-linked glutamic dehydrogenase to nicotinamide adenine dinucleotide phosphate-linked glutamic dehydrogenase, and pyridine nucleotide-nonlinked lactic dehydrogenase to pyridine nucleotide-linked lactic dehydrogenase were affected by the level of concentrates in the diet. Lactyl coenzyme A dehydrase activity was below the limits of the assay technique in many samples from the alfalfa hay diet, and increased to relatively high levels when concentrates were fed. It is suggested that the enzymatic method will prove valuable for studying the contributions of individual microorganisms to the overall ruminal metabolism, and, with certain limitations, useful for estimating the relative contributions of alternate pathways.

On the Relationship between Food Composition and Serine Dehydrase Activity in Rat Liver

Effects of the change of dietary protein on serine dehydrase activity in rat liver have been studied, using egg albumin, casein, rice protein, and wheat gluten as protein source. At 35% of dietary protein level, the activity induced by egg albumin and casein diets were higher than those by rice protein and wheat gluten diets. Parallel relation was observed between the enzyme activity and the protein intake. These results suggest that the dietary induction of this enzyme are based on the protein intake, which reflects the nutritional quality of dietary protein, rather than merely on the dietary protein level.The contribution of individual amino acid for the enzyme induction by the egg albumin diet at 35% level was investigated, and it was concluded that this enzyme induction is dependent not on a specific amino acid but on the combined effect of each amino acid.

ERYTHROPOIESIS AND DELTA-AMINOLEVULINIC ACID DEHYDRASE ACTIVITY.

The delta-aminolevulinic acid dehydrase activity of rat and mouse spleen, bone marrow and liver fractions and homo-genates was determined. Spleen ALA dehydrase specific activity of normal, polycy-themic, and anemic rats was found to decrease exponentially with the increase in hematocrit of the animal. However, sheep plasma erythropoietin, incubated with the tissue fractions and homogenates, did not directly produce an increase in enzyme activity over that of the controls.

ALA dehydrase activity in liver and kidney of rats and rabbits with experimental porphyria

ALA dehydrase activity in liver and kidney of rats and rabbits with experimental porphyria

Enzymatic activity of the rhizosphere and soils in the East Siberia area

The methods for the determination of peroxidase, polyphenoloxidase and dehydrase activity both in the soil and rhizosphere of several plants of two very different landscapes of East Siberia are described and an attempt made to find a correlation between these findings and humus content in the soil. A clear relationships was not determined which could be explained by the very complicated nature of soil redoxase activity.

The stabilizing effect of ADP and the binding of ADP by the threonine dehydrase of [formula omitted

Evidence has been presented earlier (Hayaishi, et al ., 1963) that ADP stimulates the deamination of threonine to alpha ketobutyrate by threonine dehydrase obtained from extracts of Clostridium tetanomorphum . The effect of ADP is relatively specific and is much more pronounced at low concentrations of threonine than at high concentrations. ADP does not participate directly in the reaction but markedly increases the affinity of the enzyme for its substrate (Hayaishi, et al ., 1963), i.e., ADP may be called an “allosteric effector” (Monod and Jacob, 1961; Monod, et al ., 1963). However, the mechanism by which ADP exerts its effect is unknown. The present communication describes two additional observations which may lead to an understanding of the mode of action of some allosteric effectors: 1) ADP protects threonine dehydrase activity against inactivation by dilution and heat, and 2) ADP is bound by a partially purified enzyme fraction.

Studies on the Nature, Inducibility, and Assay of the Threonine and Serine Dehydrase Activities of Rat Liver

Studies on the Nature, Inducibility, and Assay of the Threonine and Serine Dehydrase Activities of Rat Liver

Erythrocyte δ-aminolevulinic acid dehydrase activity in thalassemia major and sickle-cell anemia

An enzyme deficiency has been postulated to account for the defect in hemoglobin synthesis in certain hereditary anemias. The enzyme necessary for the conversion of δ-aminolevulinic acid to porphobilinogen, an obligatory step in heme synthesis, was assayed. The values obtained from the circulating erythrocyte of patients with thalassemia and sickle-cell anemia were higher than normal.

Deletion of serine dehydrase and cystathionine synthetase activities during azo-dye carcinogenesis.

SummarySerine dehydrase and cystathionine synthetase activities were determined in rat liver, precancerous livers, primary hepatomas induced with 3′-methyl-4-dimethylaminoazobenzene (3′-Me-DAB) and transplanted hepatomas induced with azo dyes. Both enzyme activities were absent in all malignant tissues assayed. After 4 weeks on diets containing 3′-Me-DAB both enzyme activities were reduced more than 50% but returned to normal values at 8 and 12 weeks. Precancerous alterations in these enzyme activities did not appear to be correlated with the carcinogenic activity of azo dyes employed. Deletion or alteration patterns in all tissues assayed supported the contention that both enzyme activities were manifested by a single apoenzyme.

The Relations Between Yolk and White in the Hen’s Egg

ABSTRACT The vitelline membrane of the infertile hen’s egg exhibits no dehydrase activity. The vitelline membrane has no measurable aerobic respiration in vitro, nor has the yolk of the infertile egg. This confirms the view that the carbon dioxide production of the intact egg is not the result of any true respiration. When incubated anaerobically in vitro, bacteriologically sterile yolk produces consistently small amounts of lactic acid. This glycolysis is not the result of any catalytic activity of the vitelline membrane, but takes place throughout the substance of the yolk. Under similar conditions, bacteriologically sterile yolk produces small amounts of a substance or substances estimatable as ethyl alcohol. If the yolk suspension is bacterially contaminated, however, lactic acid and alcohol are produced in amounts closely similar to those found by earlier workers on this subject. The heat of glycolysis, under anaerobic conditions, calculated from the amounts of lactic acid experimentally found to be formed, is of the same order as (a) the calculated requirement of the vitelline membrane (Straub), and (b) the observed heat production (Langworthy and Barott). Thus even if the vitelline membrane is capable of using energy to do osmotic work, the yolk is only capable of supplying it by means of its glycolytic mechanism if the whole energy output of the whole yolk can be made available for doing work at the membrane.