Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aspartate transcarbamylase (carbamoyl-phosphate: L-aspartate carbamoyltransferase, EC 2.1.3.2) has been purified from Mycobacterium smegmatis TMC 1546 using streptomycin sulphate precipitation, ammonium sulphate precipitation, DE-52 chromatography, second ammonium sulphate precipitation, Sephadex G-200 gel filtration, and aspartate-linked CNBr-activated Sepharose 4B affinity chromatography in successive order. The enzyme was purified 231.6-fold, and the preparation was found to be homogeneous on column chromatography and polyacrylamide gel electrophoresis. The purified enzyme had a molecular weight of 246,000 and was composed of two asymmetrical subunits. The kinetic and regulatory properties of aspartate transcarbamylase from M. smegmatis were also studied. The enzyme was found to be an allosteric in nature with carbamyl phosphate showing positive cooperativity and UMP exhibiting a negative cooperativity. CTP was found to be the most potent inhibitor among nucleotides. Phosphate acted as a non-competitive product inhibitor with respect to aspartate. Succinate and maleate exerted a competitive inhibition when aspartate was the variable substrate.
 ...
PMID:Purification and properties of aspartate transcarbamylase from Mycobacterium smegmatis. 334 42

We have investigated the symmetry of Na+-succinate cotransport in rabbit renal brush-border membrane vesicles. Succinate influx and efflux kinetics were measured under voltage-clamped conditions using [14C]succinate and a rapid filtration procedure. Both influx and efflux were Na+-dependent, saturable, temperature-sensitive, and influenced by the trans Na+ and succinate concentrations. The system was judged to be asymmetric, since the maximal velocity for influx was 3-fold higher than that for efflux, and trans Na+ inhibited influx more than efflux. This may be due to the asymmetrical insertion of the transporter in the brush-border membrane, which leads to differences in either the forward and backward translocation rates of the fully loaded carrier or the Na+ and succinate binding constants at the inner and outer faces of the membrane.
 ...
PMID:Asymmetry of the Na+-succinate cotransporter in rabbit renal brush-border membranes. 646 57

Two brothers, 25 and 19 years old, were affected by asymmetrical hypertrophic cardiomyopathy. The older brother had waddling gait and weakness of the proximal girdle muscles, while the younger had a broad-based gait and weakness of selected limb girdle muscles. EMG exam was myopathic. Serum enzyme, CPK and aldolase were elevated. Histochemical reactions in muscle revealed "core-like" areas, subsarcolemmal rims of mitochondria and lipid accumulation. Succinate-dehydrogenase stain showed a lack of activity in both biopsies, with the exception of intrafusal fibers. Microphotometric quantitative measurements confirmed the defect in both biopsies. Biochemical measurements of several mitochondrial enzymes in muscle showed a reduced activity of succinate-dehydrogenase (33%) and succinate-cytochrome C reductase (36-47%) which are both components of complex II. On myocardial biopsy lipid and mitochondrial abnormalities were found. This mitochondriopathy represents a new phenotype of partial complex II defect.
 ...
PMID:Hypertrophic cardiomyopathy with mitochondrial myopathy. A new phenotype of complex II defect. 851 73

The metabolism of [2,3-13C]succinic acid dimethyl ester ([2,3-13C]-SAD) 10 mmol/L was examined in hepatocytes from overnight-fasted normal rats, 3-day starved rats, and overnight-fasted hereditarily diabetic Goto-Kakizaki (GK) rats. The amount of 13C-labeled succinate, fumarate, malate, lactate, alanine, and aspartate released by the hepatocytes was much higher in fasted normal rats than in starved or diabetic animals. Although the integrated areas of the 13C2 and 13C3 signals assigned to double-labeled malate, lactate, or alanine were not significantly different, the amount of single-labeled malate, lactate, alanine, and aspartate was higher in C3- versus C2-labeled isotopomers. The release of 13C-labeled glucose by the hepatocytes was lower in fasted versus starved or diabetic rats. Virtually all hexose molecules double-labeled in the C1-C2-C3 and/or C6-C5-C4 moieties corresponded to the [1,2-13C] and/or [5,6-13C] isotopomers. However, in the case of the single-labeled species, 13C-labeling of C1 (or C6) exceeded that of C2 (or C5). Both the single- and double-labeled molecules enriched with 13C in the C1-C2-C3 moiety were less abundant than those labeled in the C6-C5-C4 moiety, with such asymmetry being most marked in overnight-fasted normal rats, less pronounced in diabetic animals, and virtually absent in starved rats. These findings document that SAD is efficiently metabolized in hepatocytes, with its use as a gluconeogenic precursor being influenced by the nutritional and hormonal status of the animals. The present experiments also reinforce the view that asymmetrical labeling of glucose by 13C-labeled precursors is modulated by the relative contribution of exogenous and endogenous nutrients to the production of triose phosphates incorporated into the hexose.
 ...
PMID:Effects of starvation and diabetes on the metabolism of [2,3-13C]succinic acid dimethyl ester in rat hepatocytes. 992 Jan 52