scholarly journals ON THE ROLE OF THIAMINE PYROPHOSPHATE IN OXIDATIVE DECARBOXYLATION OF  -KETO ACIDS

1961 ◽  
Vol 47 (6) ◽  
pp. 753-759 ◽  
Author(s):  
M. L. Das ◽  
M. Koike ◽  
L. J. Reed
Keyword(s):  
Thiamine Pyrophosphate ◽  
Oxidative Decarboxylation ◽  
Keto Acids

scholarly journals PSXIV-19 Effect of alpha-lipoic acid on productive parameters and ruminal VFA profile in sheep

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 437-438
Author(s):  
Carolina Robles ◽  
Laura Gonzáles Davalos ◽  
Ofelia Mora ◽  
Yesmin Hermanadez ◽  
Armando Shimada ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Lipoic Acid ◽  
Insulin Receptors ◽  
Daily Weight Gain ◽  
Oxidative Decarboxylation ◽  
Alpha Lipoic Acid ◽  
Randomized Design ◽  
Keto Acids ◽  
Mechanism Research

Abstract Alpha lipoic acid (LA) is a potent nutritional antioxidant. It is a derivate of octanoic acid containing a cyclic disulfide bond. An LA complex with lysine-lipoamide, functions as a co-factor in the mitochondrial dehydrogenase that catalyzes the oxidative decarboxylation of α-keto acids. In this reaction, LA is reduced to dihydrolipoic acid (DHLA), which interacts with reactive oxygen species, and LA can also inactivate free radicals. Another important role of DHLA is in signal transduction by activating insulin receptors, which causes glucose transporters translocation from cytoplasm to the cell surface. Due to its potential antioxidant effect at ruminal level, the aim of this study was to evaluate the effect of fed LA on productive parameters, ruminal fatty volatile fatty acid (VFA) concentration and blood glucose of sheep. Sixty-four, two-months-old, crossbred lambs were penned in groups of four, divided into four treatments: 0, 40, 80, and 120 ppm LA in diet. During 84 days, every 28 days on two consecutive days, animals were weighed (to determine average daily weight gain, DWG), blood and ruminal fluid were taken for glucose and VFA quantification, respectively. All variables were analyzed in a completely randomized design. DWG was statistically higher in those animals receiving 80 ppm (250 g) as compared to the rest (200, 188, 180 g for 120, 40, 0 ppm, respectively) (P < 0.0001). No differences in blood glucose or ruminal VFA were found (P > 0.1). LA could improve the productive performance of sheep; however, it would be necessary to study the role of LA and its effects on the ruminal microbiome and its action mechanism. Research support by Project PAPIIT-UNAM IN211518

Ammonia toxicity and cerebral oxidative metabolism

1961 ◽  
Vol 200 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Guy M. McKhann ◽  
Donald B. Tower
Keyword(s):  
Oxidative Metabolism ◽  
Incubation Medium ◽  
Lactic Acid Production ◽  
Ammonia Toxicity ◽  
Thiamine Pyrophosphate ◽  
Oxidative Decarboxylation ◽  
Cortex Slices ◽  
The Brain ◽  
Cat Cerebral Cortex

Effects of NH4Cl on oxidative metabolism of cat cerebral cortex slices and mitochondria incubated in vitro were studied. In slices, addition of 10 mm NH4Cl to the incubation medium resulted in significant (16%) reduction of O2 uptake, doubling of lactic acid production and marked increase of glucose utilization compared to control slices. Mitochondria showed a 30–40% decrease of O2 consumption in the presence of 15 mm NH4Cl when pyruvate or α-ketoglutarate were substrates, but little if any difference from controls with succinate, glutamic acid or γ-aminobutyric acid as substrates. Pyruvate utilization by ammonia-treated mitochondria was inhibited to the same degree as O2 consumption and was not increased by supplementing the incubation medium with excess succinate. Additions of α-lipoic acid, thiamine pyrophosphate or DPN to such preparations failed to reverse the NH4Cl effect. Satisfactory P/O ratios were obtained for all mitochondrial preparations. It is concluded that a primary toxic effect of ammonia on the brain may be direct interference with oxidative decarboxylation of pyruvic and α-ketoglutaric acids.

INFLUENCE OF THIAMINE AND TRYPTOPHAN UPON THE TRYPTOPHAN PEROXIDASE–OXIDASE ACTIVITY OF RAT LIVER

1958 ◽  
Vol 36 (7) ◽  
pp. 659-667 ◽  
Author(s):  
Edith E. Townsend ◽  
T. L. Sourkes
Keyword(s):  
Rat Liver ◽  
Oxidase Activity ◽  
Thiamine Pyrophosphate ◽  
Enzyme Content

The possible role of thiamine in the oxidation of tryptophan by tryptophan peroxidase–oxidase (TPO) of liver was studied by several approaches. (1) In acute experiments parenterally administered thiamine did not cause an adaptive increase in the enzyme content of rat liver, as can be induced by similar injection of tryptophan. (2) Thiamine pyrophosphate, added to liver extracts which had been partially inactivated with respect to TPO by aging for one-half hour at 37 °C. or by prolonged dialysis, did not reactivate the enzyme oxidizing tryptophan. (3) In multifactorial dietary experiments in which thiamine, tryptophan, or both were omitted from the diet only tryptophan deficiency resulted in a decrease of the liver TPO activity. There was no effect of thiamine, either in the presence or absence of tryptophan. The D- and L-isomers of tryptophan were equally effective in promoting TPO activity. These results do not support the findings of other authors who imply a role for thiamine in the oxidation of tryptophan by TPO.

Kinetic serum creatinine assays I. The role of various factors in determining specificity.

1980 ◽  
Vol 26 (5) ◽  
pp. 551-554
Author(s):  
L D Bowers
Keyword(s):  
Serum Creatinine ◽  
Rate Constants ◽  
Kinetic Methods ◽  
Relative Value ◽  
Keto Acids ◽  
Measuring Techniques ◽  
Main Factors ◽  
Analytical Reagent ◽  
Kinetic Methods Of Analysis

Abstract We studied the specificity of kinetic methods of analysis, with emphasis on creatinine determination. The error contributed by an interferent that reacts with the analytical reagent and absorbs at the wavelength of analysis is shown to be related to the ratio of the equilibrium absorbances of the analyte and interferent, the ratio of the rate constants, the extent of the analytical reaction, and the duration of the measurement. To assess the potential diminution of the interference with kinetic methods, we determined the rate constants of several alpha-keto acids in the Jaffé reaction. Evaluation of the advantages of various measuring techniques with respect to specificity showed the main factors to be the extent of the analytical reaction and the relative value of the rate constants. Total specificity for creatine appears to be unattainable with currently used kinetic techniques.

THE ROLE OF KETO ACIDS IN PHOTOSYNTHETIC CARBON DIOXIDE ASSIMILATION

1956 ◽  
Vol 34 (1) ◽  
pp. 511-519 ◽  
Author(s):  
G. H. N. Towers ◽  
D. C. Mortimer
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Sugar Beet ◽  
Aspartic Acid ◽  
Pyruvic Acid ◽  
Carbon Dioxide Assimilation ◽  
Free Air ◽  
Keto Acids ◽  
Photosynthetic Carbon

Of the keto acids identified in leaves of sugar beet and other plants exposed to C14O2, pyruvic acid was found to be the only one labelled in light periods up to 45 sec. α-Ketoglutaric and glyoxylic acids became radioactive after about 45 sec. Radioactive hydroxypyruvate was not identified under these conditions and labelled oxaloacetate was detected only in trace amounts after 60 sec. in Scenedesmus. In contrast glycine and serine were labelled after 10 sec. under comparable conditions and aspartic acid was appreciably labelled after 30 sec. The effect on the radioactivity of the keto acids of an additional period intracer-free air, with and without light, as well as the dark incorporation of C14O2 was studied. These results are discussed in relation to the role of the ketoacids in photosynthesis. It is concluded that the synthesis of amino acids such as glycine, serine, and aspartic acid may be effected by mechanisms other than transamination in green leaves in the light.

Intermediate role of α-keto acids in the formation of Strecker aldehydes

2013 ◽  
Vol 141 (2) ◽  
pp. 1140-1146 ◽  
Author(s):  
Francisco J. Hidalgo ◽  
Rosa M. Delgado ◽  
Rosario Zamora
Keyword(s):  
Keto Acids ◽  
Strecker Aldehydes ◽  
Intermediate Role

scholarly journals New Insight into the Role of the Calvin Cycle: Reutilization of CO2 Emitted through Sugar Degradation

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Rie Shimizu ◽  
Yudai Dempo ◽  
Yasumune Nakayama ◽  
Satoshi Nakamura ◽  
Takeshi Bamba ◽  
...  
Keyword(s):  
Ralstonia Eutropha ◽  
Calvin Cycle ◽  
Oxidative Decarboxylation ◽  
Carbon Yield ◽  
Efficient Utilization ◽  
Sugar Degradation ◽  
Biomass Resources ◽  
Insight Into ◽  
Reducing Equivalents

Abstract Ralstonia eutropha is a facultative chemolithoautotrophic bacterium that uses the Calvin–Benson–Bassham (CBB) cycle for CO2 fixation. This study showed that R. eutropha strain H16G incorporated 13CO2, emitted by the oxidative decarboxylation of [1-13C1]-glucose, into key metabolites of the CBB cycle and finally into poly(3-hydroxybutyrate) [P(3HB)] with up to 5.6% 13C abundance. The carbon yield of P(3HB) produced from glucose by the strain H16G was 1.2 times higher than that by the CBB cycle-inactivated mutants, in agreement with the possible fixation of CO2 estimated from the balance of energy and reducing equivalents through sugar degradation integrated with the CBB cycle. The results proved that the ‘gratuitously’ functional CBB cycle in R. eutropha under aerobic heterotrophic conditions participated in the reutilization of CO2 emitted during sugar degradation, leading to an advantage expressed as increased carbon yield of the storage compound. This is a new insight into the role of the CBB cycle and may be applicable for more efficient utilization of biomass resources.

On the mechanism of oxidative decarboxylation of α-keto acids

1958 ◽  
Vol 29 (1) ◽  
pp. 218-219 ◽  
Author(s):  
D.R. Sanadi ◽  
Martha Langley ◽  
Fred White
Keyword(s):  
Oxidative Decarboxylation ◽  
Keto Acids

THE ROLE OF KETO ACIDS IN PHOTOSYNTHETIC CARBON DIOXIDE ASSIMILATION

1956 ◽  
Vol 34 (3) ◽  
pp. 511-519 ◽  
Author(s):  
G. H. N. Towers ◽  
D. C. Mortimer
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Sugar Beet ◽  
Aspartic Acid ◽  
Pyruvic Acid ◽  
Carbon Dioxide Assimilation ◽  
Free Air ◽  
Keto Acids ◽  
Photosynthetic Carbon

Of the keto acids identified in leaves of sugar beet and other plants exposed to C14O2, pyruvic acid was found to be the only one labelled in light periods up to 45 sec. α-Ketoglutaric and glyoxylic acids became radioactive after about 45 sec. Radioactive hydroxypyruvate was not identified under these conditions and labelled oxaloacetate was detected only in trace amounts after 60 sec. in Scenedesmus. In contrast glycine and serine were labelled after 10 sec. under comparable conditions and aspartic acid was appreciably labelled after 30 sec. The effect on the radioactivity of the keto acids of an additional period intracer-free air, with and without light, as well as the dark incorporation of C14O2 was studied. These results are discussed in relation to the role of the ketoacids in photosynthesis. It is concluded that the synthesis of amino acids such as glycine, serine, and aspartic acid may be effected by mechanisms other than transamination in green leaves in the light.

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