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Results for “Keto Acids”

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At least 91 records · Page 5Linked to original sources
PubMed1987

Altered kinetic properties of the branched-chain alpha-keto acid dehydrogenase complex due to mutation of the beta-subunit of the branched-chain alpha-keto acid decarboxylase (E1) component in lymphoblastoid cells derived from patients with maple syrup urine disease.

Branched-chain alpha-keto acid dehydrogenase (BCKDH) complexes of lymphoblastoid cell lines derived from patients with classical maple syrup urine disease (MSUD) phenotypes were studied in terms of their catalytic functions and analyzed by immunoblotting, using affinity purified anti-bovine BCKDH antibody. Kinetic studies on three cell lines derived from patients with the classical phenotype showed sigmoidal or near sigmoidal kinetics for overall BCKDH activity and a deficiency of the E1 component activity. An immunoblot study revealed a markedly decreased amount of the E1 beta subunit accompanied by weak staining of the E1 alpha subunit. The E2 and E3 component exhibited a cross-reactive peptide. Thus, in at least some patients with MSUD, mutations of the E1 beta subunit might provide an explanation for the altered kinetic properties of the BCKDH complex.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1978

Comparison of the effects of keto acid analogues and essential amino acids on nitrogen homeostasis in uremic patients on moderately protein-restricted diets.

Comparisons of isonitrogenous supplements (1.2 g N) of essential amino acids and five keto acid analogues with four essential amino acids were made in seven patients with stable chronic renal failure (creatinine clearance, 4.6 to 16 ml/min) on moderately protein-restricted diets (4.60 to 7.8 g N per day). Full nitrogen balance data on the four patients who have already completed studies lasting 24 weeks are presented. No benefits of keto acid over amino acid supplements were observed. Two transient episodes of hypercalcemia occurred during keto acid treatment. There was no improvement of renal function with keto acids. Also, no carry-over effects were seen after keto acid treatment. It is concluded that any beneficial effects of keto acids in patients with chronic renal failure are only likely to occur in those taking a diet of less than 30 g protein daily.

Adult↗
PubMed1986

Plasma level of branched chain alpha-amino acids following its alpha-keto acid administration to rats.

To detect the effective substance accelerating the conversion of branched chain alpha-keto acids (BCKA) to corresponding amino acids, some sugars, sugar alcohols, ethanol, octanoate and ATP were tested with intravenous injection of three BCKA to rats. Plasma leucine levels 30 min after BCKA injection in rats, which were infused with 2 M solution of fructose or sorbitol, reached the significantly high peak corresponding to 860% and 790% of the basal levels. Administration of ethanol (2 or 3.5 M) or octanoate (4.5 mM) also resulted in significantly high levels of leucine in plasma following BCKA injection as compared with control. Molar ratio of plasma branched chain amino acid (BCAA)/aromatic amino acid 30 min after BCKA injection increased to 12.9 in control rats. The ratios 60 and 120 min after BCKA administration were significantly higher in rats treated with ethanol (3.5 M) or octanoate (4.5 mM) than those in control. These results suggest that infusion of the metabolites inducing high NADH/NAD ratio in their metabolic pathways results in inhibition of BCKA decarboxylation and, as a result, enhancement of transamination of BCKA into BCAA.

Adenosine Triphosphate↗
PubMed2003

9alpha-Fluoro-16alpha-methyl-3,11-dioxoandrosta-1,4-diene-17beta-carboxylic acid: catemeric hydrogen bonding and acetic acid solvation in a steroidal keto acid related to dexamethasone.

The title keto acid crystallizes as a solvate, C(21)H(25)FO(4).C(2)H(4)O(2), with two molecules each of steroid and acetic acid per asymmetric unit. The former are approximately parallel, with opposite end-to-end orientation, and form translational carboxyl-to-ketone hydrogen-bonding catemers [O...O = 2.679 (6) and 2.650 (5) A, and O-H...O = 165 and 162 degrees] that involve the 3-ketone group and follow the a axis. The acetic acid molecules are paired by hydrogen bonding, and neither they nor the F atom nor the 11-ketone group play any overt role in the hydrogen-bonding scheme of the steroid. Intermolecular C-H...O=C close contacts involving three different neighboring molecules exist to the 11-ketone group, the steroidal carboxyl group and one of the acetic acid molecules.

Journal Article↗
PubMed1986

Blood-brain barrier transport of the alpha-keto acid analogs of amino acids.

A number of alpha-keto acid analogs of amino acids have been found to penetrate the blood-brain barrier (BBB). Pyruvate, alpha-ketobutyrate, alpha-ketoisocaproate, and alpha-keto-gamma-methiolbutyrate all cross the BBB by a carrier-mediated process and by simple diffusion. Under normal physiological conditions, diffusion accounts for roughly 15% or less of total transport. Aromatic alpha-keto acids, phenylpyruvate, and p-hydroxyphenylpyruvate do not penetrate the BBB, nor do they inhibit the transport of other alpha-keto acids. Evidence based primarily on inhibition studies indicates that the carrier-mediated transport of alpha-keto acids occurs via the same carrier demonstrated previously for propionate, acetoacetate, and beta-hydroxybutyrate transport, commonly referred to as the monocarboxylate carrier. As a group, the alpha-keto acid analogs of the amino acids have the highest affinity for the carrier, followed by propionate and beta-hydroxybutyrate. Starvation for 4 days induces transport of alpha-keto acids, but transport is suppressed in rats fed commercial laboratory rations and subjected to portacaval shunts. The mitochondrial pyruvate translocator inhibitor alpha-cyanocinnamate has no effect on the BBB transport of alpha-keto acids.

3-Hydroxybutyric Acid↗
PubMed2001

(+)-3-oxo-4-pregnene-20beta-carboxylic acid: catemeric hydrogen bonding in a steroidal keto acid.

The title keto acid, (+)-23,24-dinor-3-oxochol-4-en-22-oic acid, C(22)H(32)O(3), forms carboxyl-to-ketone hydrogen-bonding catemers [O...O = 2.699 (4) A and O-H...O = 173 degrees ], linking molecules screw-related in b. The four molecules in the cell form two parallel counter-directional chains, screw-related in a. Intermolecular C-H...O=C close contacts to different neighboring molecules were found for the ketone and the acid.

Crystallography, X-Ray↗
PubMed1984

Effects on plasma amino acid concentrations and hepatic branched-chain alpha-keto acid dehydrogenase activity of feeding rats diets containing 9 or 50% casein.

Plasma concentrations of amino acids and alpha-ketoisocaproate and alpha-keto-gamma- methiolbutyrate decarboxylation activities in livers of rats trained to eat 9 or 50% casein diets for 5 hours/day, were measured one-half hour before and one-half and 3 hours after the start of the feeding period. Decarboxylation of both alpha-ketoisocaproate and alpha-keto-gamma- methiolbutyrate by liver increased significantly within one-half hour after rats had ingested either the 9 or the 50% casein diet. Liver decarboxylation activity of rats fed the 50% casein diet was from two- to fivefold higher than that of rats fed the 9% casein diet. The greatest difference was observed when calcium, NAD and coenzyme A were included in the decarboxylation assay medium. Although the activity of the branched-chain alpha-keto acid dehydrogenase increased in response to food ingestion, plasma concentrations of branched-chain amino acids also increased greatly after the ingestion of food. The similarity in the responses of alpha-ketoisocaproate and alpha-keto-gamma- methiolbutyrate decarboxylation in rats fed diets differing in protein content and subjected to different feeding regimens allows us to suggest that the branched-chain alpha-keto acid dehydrogenase is responsible, in part, for the oxidative decarboxylation of the alpha-keto acid analog of methionine. J. Nutr . 114: 1025-1034, 1984.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed2004

pH-Dependent chemoselective synthesis of alpha-amino acids. Reductive amination of alpha-keto acids with ammonia catalyzed by acid-stable iridium hydride complexes in water.

An acid-stable hydride complex [Cp*IrIII(bpy)H]+ {1, Cp* = eta5-C5Me5, bpy = 2,2'-bipyridine} serves as the active catalyst for the highly chemoselective synthesis of alpha-amino acids by reductive amination of alpha-keto acids with aqueous NH3 and HCOO- in water at pH 5-8. pH-dependent catalytic 15N- and 2H-double-labeling has also been accomplished by using 15NH3 and DCOONa, which are ideal amine and hydride ion sources, respectively.

Amination↗