1. Double-reciprocal plots of the reaction velocity of yeast, rat liver and Escherichia coli ATP-l-methionine S-adenosyltransferases (EC 2.5.1.6) as a function of the l-methionine concentrations (under saturating ATP conditions) demonstrate downward deflexions from linearity for the yeast and E. coli adenosyltransferases and an upward deflexion for the rat liver enzyme. 2. The activities of par...

This study has the main purpose of testing natural carriers as more sustainable alternatives to polymeric coating. New clay-based hybrid organic–inorganic materials have been prepared. An innovative procedure for intercalation bioactive molecule is proposed. The synthesis process implies use mild operating conditions and does not require organic reactants or solvents. Moreover, carriers, milder...

In mammals, methionine adenosyltransferase (MAT), the enzyme responsible for S-adenosylmethionine (AdoMet) synthesis, is encoded by two genes, MAT1A and MAT2A. In liver, MAT1A expression is associated with high AdoMet levels and a differentiated phenotype, whereas MAT2A expression is associated with lower AdoMet levels and a dedifferentiated phenotype. In the current study, we examined regulati...

BACKGROUND Children with edematous but not nonedematous severe childhood undernutrition (SCU) have lower plasma and erythrocyte-free concentrations of cysteine and methionine, which suggests a decreased availability of methionine for cysteine synthesis. We propose that methionine production and metabolism will be slower in children with edematous SCU than in those with nonedematous SCU. OBJEC...

The renal transport and fractional reabsorption of inorganic sulfate is altered under conditions of sulfate deficiency or excess. The objective of this study was to examine the cellular mechanisms of adaptation of renal sodium/sulfate cotransport after varying dietary intakes of a sulfur containing amino acid, methionine. Female Lewis rats were divided into four groups and fed diets containing ...

The megaloblastic anemia of cobalamin deficiency appears secondary to decreased methionine synthetase activity. Decreased activity of this enzyme should cause 5-methyltetrahydrofolate to accumulate intracellularly, and consequently, decrease purine and DNA synthesis; this is the basis of the "methylfolate trap" hypothesis of cobalamin deficiency. However, only some of the clinical and biochemic...

OBJECTIVE Restricting dietary methionine to 0.17% produces a series of physiological responses through coordinated transcriptional effects in liver and adipose tissue. The goal of the present work was to determine the threshold concentrations above and below 0.17% at which the beneficial responses to 0.17% dietary methionine are preserved. METHODS Diets were formulated to restrict methionine ...

Methionine is an essential amino acid for animals and is typically considered one of the first limiting amino acids in animal feed formulations. Methionine deficiency or excess in animal diets can lead to sub-optimal animal performance and increased environmental pollution, which necessitates its accurate quantification and proper dosage in animal rations. Animal bioassays are the current indus...

PURPOSE To evaluate the differences between fludeoxyglucose F 18 (FDG) and L-methyl-11C-methionine (11C-methionine) as tracers for positron emission tomography (PET) in the evaluation of brain tumors. METHODS We analyzed 10 patients with histologically verified cerebral glioma or meningioma and 1 patient with a neuroradiologic diagnosis of low-grade glioma by using FDG, 11C-methionine, and PE...