Search results for "Transamination"
showing 10 items of 10 documents
Structural Analysis of Phosphoserine Aminotransferase (Isoform 1) From Arabidopsis thaliana– the Enzyme Involved in the Phosphorylated Pathway of Ser…
2018
Phosphoserine aminotransferase (PSAT) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the conversion of 3-phosphohydroxypyruvate (3-PHP) to 3-phosphoserine (PSer) in an L-glutamate (Glu)-linked reversible transamination reaction. This process proceeds through a bimolecular ping-pong mechanism and in plants takes place in plastids. It is a part of the phosphorylated pathway of serine biosynthesis, one of three routes recognized in plant organisms that yield serine. In this three-step biotransformation, 3-phosphoglycerate (3-PGA) delivered from plastidial glycolysis and Calvin cycle is oxidized by 3-PGA dehydrogenase. Then, 3-PHP is subjected to transamination with Glu to yi…
Spontaneous Resolution of a Triple‐Stranded Dinickel(II) Helicate Generated via Intermolecular Transamination Reaction of S ‐Methylisothiocarbohydraz…
2008
The reaction of S-methylisothiocarbohydrazide hydroiodide [H2NNHC(SCH3)NNH2·HI] with NiCl2·6H2O in water at room temperature yielded a triple-stranded dinickel(II) helicate [NiII(L1–L1)3NiII]I4·4H2O (14+·4I–·4H2O), where L1–L1 = H2NNHC(SCH3)NNC(SCH3)NHNH2, in 35 % yield, which spontaneously separates in enantiomers upon crystallization. The enantiomers do not racemize at room temperature, even not after 15 h of heating at 90 °C. X-ray diffraction structures of both enantiomers, chiroptical and magnetic properties of 14+·4I–·4H2O are reported. Demetallation of the complex by treatment with S2– resulted in 3,6-bis(methylthio)-1,4-dihydro-1,2,4,5-tetrazine (2). Compound 2 undergoes 2-e– oxidat…
Adaptive physiological water conservation explains hypertension and muscle catabolism in experimental chronic renal failure
2021
Abstract Aim We have reported earlier that a high salt intake triggered an aestivation‐like natriuretic‐ureotelic body water conservation response that lowered muscle mass and increased blood pressure. Here, we tested the hypothesis that a similar adaptive water conservation response occurs in experimental chronic renal failure. Methods In four subsequent experiments in Sprague Dawley rats, we used surgical 5/6 renal mass reduction (5/6 Nx) to induce chronic renal failure. We studied solute and water excretion in 24‐hour metabolic cage experiments, chronic blood pressure by radiotelemetry, chronic metabolic adjustment in liver and skeletal muscle by metabolomics and selected enzyme activity…
Enzymatic and pharmacokinetic studies on the metabolism of branched chain alpha-keto acids in the rat.
1983
Michaelis-constants and enzyme activities for dehydrogenation and transamination of the three branched chain alpha-keto acids in liver, kidney, skeletal muscle, and brain of rats are reported. After oral load only 11-22% of the keto acids pass the liver unchanged. Blood levels in pharmacokinetic and absorption studies are related to the Michaelis-constants. At the low keto-acid concentrations after oral application, dehydrogenation in the non-hepatic tissues is supposed to prevail over transamination. Data on feed efficiency of branched chain alpha-keto acids reported in the literature support this view. The chance for transamination is better after intravenous administration. The transfera…
Methylthioacetaldehyde, a possible intermediate metabolite for the production of volatile sulphur compounds from L-methionine by Lactococcus lactis
2004
Volatile sulphur compounds (VSCs) production from L-methionine was studied in Lactococcus lactis. In vitro studies with radiolabelled L-methionine and resting cells of L. lactis revealed that L-methionine was initially converted to alpha-keto-gamma-methylthiobutyrate (KMBA) by a transamination reaction. A part of KMBA was subsequently chemically converted to methylthioacetaldehyde, methanethiol and dimethylsulphides. Chemical conversion of KMBA to methylthioacetaldehyde was dependent on pH, Mn(II) and oxygen. Since methanethiol and dimethylsulphide production was highly related to that of methylthioacetaldehyde, the latter compound was proposed as being an intermediate in VSCs production by…
Inactivation of lactococcal aromatic aminotransferase prevents the formation of flora aroma compounds from aromatic amino acids in semi-hard cheese
1999
The enzymatic conversion of aromatic amino acids to aroma compounds plays a role in the formation of an undesirable floral aroma in Cheddar-like cheeses. In lactococci, the first step of aromatic amino acid degradation is a transamination, catalysed by an aromatic aminotransferase (AraT). We observed previously that in vitro, araT inactivation prevented degradation of aromatic amino acids and decreased degradation of Met and Leu. In this study we evaluated the effect of araT inactivation in Lactococcus lactis on flavour development in St. Paulin-type cheese. The degradation of amino acids was monitored by using radiolabelled amino acids and the volatile compounds formed were analysed by GC-…
Chemical recycling of polyenaminones by transamination reaction via amino–enaminone polymerisation/depolymerisation
2019
Abstract Novel oligo- and polyenaminones with Mw ∼ 3000 Da were prepared in excellent yields by amino–enaminone ‘click’ polymerisation of 1,3- and 1,4-bis[3-(dimethylamino)acryloyl]arenes with 1,3- and 1,4-phenylenediamine. The obtained oligomers and polymers were depolymerised quantitatively to the starting bis-enaminones and diamines by treatment with excess dimethylamine in ethanol at 50 °C. This simple polymerisation/depolymerisation method allows for a closed-loop recycling of polyenaminone-based materials. UV light absorbance at wavelengths below 470 nm indicates promising optical properties of these polymers.
Effect of Glufosinate (Phosphinothricin) and Inhibitors of Photorespiration on Photosynthesis and Ribulose-1,5-Bisphosphate Carboxylase Activity
1992
Summary Glufosinate (phosphinothricin) irreversibly inhibits glutamine synthetase and leads to a great decrease in the amino acids glutamine, glutamate, aspartate, serine, glycine and alanine. Due to the lack of glutamate and serine, the transamination of glyoxylate into glycine in the course of photorespiration cannot take place. The inhibition of this part of the photorespiratory process plays the essential role with respect to the photosynthesis inhibition caused by PPT under atmospheric conditions. After addition of different photorespiration or Calvin cycle intermediates to phosphinothricin no decrease in photosynthesis inhibition can be measured. This suggests that photosynthesis inhi…
ChemInform Abstract: Exploiting the CNC Side Chain in Heterocyclic Rearrangements: Synthesis of 4(5)-Acylamino-imidazoles.
2010
A new variation on the Boulton-Katritzky reaction is reported, namely, involving use of a CNC side chain. A novel Montmorillonite-K10 catalyzed nonreductive transamination of a 3-benzoyl-1,2,4-oxadiazole afforded a 3-(alpha-aminobenzyl)-1,2,4-oxadiazole, which was condensed with benzaldehydes to afford the corresponding imines. In the presence of strong base, these imines underwent Boulton-Katritzky-type rearrangement to afford novel 4(5)-acylaminoimidazoles.
Exploiting the CNC Side Chain in Heterocyclic Rearrangements: Synthesis of 4(5)-Acylamino-imidazoles
2010
A new variation on the Boulton-Katritzky reaction is reported, namely, involving use of a CNC side chain. A novel Montmorillonite-K10 catalyzed nonreductive transamination of a 3-benzoyl-1,2,4-oxadiazole afforded a 3-(alpha-aminobenzyl)-1,2,4-oxadiazole, which was condensed with benzaldehydes to afford the corresponding imines. In the presence of strong base, these imines underwent Boulton-Katritzky-type rearrangement to afford novel 4(5)-acylaminoimidazoles.