The pKa value of Lys115, the catalytic residue in acetoacetate decarboxylate, was calculated using atomic coordinates of the X-ray crystal structure with consideration of the protonation states of all titratable sites in the protein. The calculated pKa value of Lys115 (pKa(Lys115)) was unusually low (approximately 6) in agreement with the experimentally measured value. Although charged residues...

We have investigated the application of multipoint kinetic curve-fitting methods to the determination of an analyte in the presence of a single interferent. Our model system for the analyte-interferent was creatinine-acetoacetate as determined with the kinetic Jaffé method. We examined the utility of the following multipoint approaches: simultaneous equations, multivariable linear regression, a...

An organism belonging to Pseudomonadaceae and capable of utilizing 3-hydroxy-3-methylglutarate as sole carbon source has been isolated from soil. Whole-cell preparations catalyze the oxidation of acetoacetate, acetate, glyoxylate, and citric acid cycle intermediates. Cell-free extracts of 3-hydroxy-3-methylglutarate-grown cells show an adenosine triphosphate, coenzyme A (CoA), and Mg(2+)-depend...

This is a multipoint kinetic method for simultaneously determining acetoacetate (AcAc) plus beta-hydroxybutyrate and lactate plus pyruvate in a single cuvette of the Multistat III centrifugal analyzer. In the first step, AcAc and pyruvate are completely reduced, using 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) and lactate dehydrogenase (EC 1.1.1.27) in the presence of excess NADH at pH 7.5, ...

1. The synthesis of phosphoenolpyruvate and the O(2) consumption from the tricarboxylic acid-cycle intermediates citrate, alpha-oxoglutarate, malate and succinate by guinea-pig mitochondria were compared. Malate was the most effective of these precursors; there was no synthesis of phosphoenolpyruvate from succinate. 2. The addition of palmitate, acetoacetate and ATP enhanced the synthesis of ph...

Hypertonic glucose, fructose, and sorbitol solutions were given intravenously to women in the first stage of labour who had ketonuria and ketonaemia as evidenced by a raised blood acetoacetate and 3-hydrosybutyrate. There was no difference in the antiketogenic action of these, which was rapid and effective, but when compared with a control group who were given normal saline they had a high inci...

We assessed the reproducibility, recovery, and stability of several circulating metabolites--glucose, pyruvate, lactate, alanine, glutamate, glutamine, 3-hydroxybutyrate, acetoacetate, and glycerol--in the presence of sulfosalicylic acid (SSA), which was used to deproteinize blood. The assays, which involved reactions linked to NADH/NAD+, were carried out at 37 degrees C and measured at 355 nm ...

I . An experiment was performed to study the eEect of sodium acetoacetate on urinary excretion of santhurenic acid and other tryptophan metabolites in male albino rats. z. Animals were fed on a nicotinic acid-deficient diet for a period of 3 weeks. The animals were then divided into two groups and, after the basal urinary excretion of the tryptophan metabolites had been estimated, the rats of b...

Fumarylacetoacetate hydrolase (FAH) hydrolyzes fumarylacetoacetate to fumarate and acetoacetate, the final step in the tyrosine (Tyr) degradation pathway that is essential to animals. Deficiency of FAH in animals results in an inborn lethal disorder. However, the role for the Tyr degradation pathway in plants remains to be elucidated. In this study, we isolated an Arabidopsis (Arabidopsis thali...

In previous studies we have reported that a) marked sensitivity to leucine hypoglycemia can be induced consistently in healthy subjects after the oral administration of sulfonylureas, compounds that are known to stimulate islet cell activity (1), b) a modest but significant hypoglycemic effect can be produced by administering leucine to healthy subjects without sulfonylurea pretreatment (1, 2),...