Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Frontal and zonal analysis of the chromatography of aspartate aminotransferase (EC2.61.1), pig heart cytosolic enzyme, on Bio-Gel P150 shows that holo- and apoenzyme can dissociate at pH 8.3. Ultracentrifugation and fluorescence depolarization confirm this result. Kinetic analysis of the fluorescence depolarization experiments favors a biphasic phenomenon: a few minutes for the faster one and several hours for the slower one. The apparent dissociation constant is 0.8 muM for the apoenzyme and 0.18 muM for the pyridoxal 5'-phosphate form of the holoenzyme. In the presence of sucrose or 0.1 M L-aspartate or a mixture of 70 mM L-glutamate and 2 mM alpha-ketoglutarate, the holoenzyme is dimeric at concentrations higher than 5 nM. The addition of a mixture of the substrates L-glutamate and alpha-ketoglutarate to a monomeric holoenzyme leads to dimerization. The stability of the dimeric form is in the order: holoenzyme + substrates greater than apoenzyme.
 ...
PMID:Dissociation of aspartate aminotransferase into subunits. Effect of ligands upon this dissociation. 119 65

1. Gel electrophoresis of aspartate aminotransferase released from boar spermatozoa after cold shock showed one band migrating towards anode. 2. Physico-chemical and kinetic properties of isolated enzyme were similar to cytoplasmic isoenzyme of AAT from somatic tissues.
 ...
PMID:Isolation and characteristics of aspartate aminotransferase from boar spermatozoa. 251 80

A peptide (extra signal peptide) comprising amino acids 1-29 of pig liver pre-mitochondrial aspartate aminotransferase (p-mAAT) was synthesized chemically. The peptide was found to block the import of rat liver p-mAAT into rat liver mitochondria. An antibody raised against the peptide immunoprecipitated rat liver p-mAAT synthesized in a rabbit reticulocyte cell-free translation system. These results suggested that the extra signal peptide sequence of p-mAAT is essential for import of p-mAAT into the mitochondria and that there is structural homology between the extra signal peptides of pig and rat liver p-mAAT. An anti-idiotypic antibody against the peptide was also prepared and purified by affinity chromatography on an Affi-Gel 10 anti-peptide IgG column and was then characterized.
 ...
PMID:An antibody and anti-idiotypic antibody against the extra signal peptide of pre-aspartate aminotransferase. 282 94

The mitochondrial enzymes citrate synthase, malate dehydrogenase, and aspartate aminotransferase were purified to homogeneity from porcine hearts by use of Bio-Rex 70, carboxymethylcellulose CM32, and Affi-Gel blue chromatography. This procedure provides relatively rapid, large-scale preparation of the three enzymes based on their differential binding to commercially available cation-exchange resins followed by a final affinity chromatography step.
 ...
PMID:Concomitant purification of three porcine heart mitochondrial enzymes: citrate synthase, aspartate aminotransferase, and malate dehydrogenase. 398 11

Pretreatment with Mn2+ is known to produce tolerance to Cd2+-induced lethality. This study was designed to determine the mechanism of tolerance to Cd2+-induced lethality and hepatotoxicity following Mn2+ pretreatment. Rats given 36 mumoles Cd2+/kg, i.v., died within 10-20 hr while only one of nine rats pretreated with Mn2+ (250 mumoles/kg, s.c., 48 and 24 hr prior to Cd2+ challenge) died. Ten hours after Cd2+, plasma aspartate aminotransferase and sorbitol dehydrogenase activities were elevated markedly, and extensive histopathologic lesions of the liver were evident in control rats but not in Mn2+-pretreated rats. To examine the mechanism of this tolerance, distribution of Cd2+ to fourteen organs and the subcellular distribution in six organs were determined in control and Mn2+-pretreated rats. Two hours after challenge (31 mumoles Cd2+/kg, i.v., 0.75 microCi 109Cd2+/mumol Cd2+), the distribution of Cd2+ to liver markedly increased after Mn2+ pretreatment with concomitant decreases in other tissues. Mn2+ pretreatment also resulted in a marked difference in the hepatic subcellular distribution of Cd2+ with more present in cytosol and less associated with organelles. Gel-filtration chromatography indicated that most cytosolic Cd2+ was bound to a low molecular weight protein. Isolation and partial characterization of this protein suggest that it is identical to metallothionein (MT); it had a similar relative elution following gel-filtration chromatography, had low absorbance at 280 nm and, after separation into two isoproteins by DEAE A-25 anion exchange chromatography, had the same mobility after electrophoresis on non-denaturing polyacrylamide gels as Cd2+-induced metallothioneins. These data suggest that Mn2+ pretreatment reduces Cd2+-induced hepatotoxicity by altering the hepatic subcellular distribution of Cd2+ with more Cd2+ binding to MT in the cytosol. This decreased hepatotoxicity is probably responsible for tolerance to Cd2+-induced lethality.
 ...
PMID:Mechanism of manganese-induced tolerance to cadmium lethality and hepatotoxicity. 399 53

Pretreatment with Zn is known to produce tolerance to several toxic effects of Cd. This study was designed to determine if zinc pretreatment decreased Cd-induced lethality and hepatotoxicity. Rats given 4.0 mg Cd/kg, iv, died within 10 to 20 hr while there was no mortality in rats pretreated with Zn (12 mg Zn/kg, sc, 48 and 24 hr prior to Cd challenge). Ten hr after Cd, plasma aspartate aminotransferase and sorbitol dehydrogenase activities were markedly elevated and extensive histopathologic lesions of the liver were evident in control rats while such injury was not evident in Zn-pretreated rats. To examine the mechanism of this tolerance, distribution of Cd to 14 organs and the subcellular distribution in 6 organs (liver, kidneys, intestines, heart, spleen, and testes) was determined in control and Zn-pretreated rats. Two hours after challenge (3.5 mg Cd/kg, iv, 7 microCi 109Cd/mg Cd), the distribution of Cd to the liver markedly increased after Zn pretreatment without concomitant decreases in other tissues. Zn pretreatment resulted in distribution of more Cd to hepatic cytosol and less associated with endoplasmic reticulum. Gel filtration chromatography indicated that most cytosolic Cd was bound to metallothionein. These data suggest that Zn pretreatment reduces Cd-induced hepatotoxicity which prevents the lethal effects of Cd possibly by altering the hepatic subcellular distribution of Cd.
 ...
PMID:Zinc-induced tolerance to cadmium hepatotoxicity. 674 Jun 79

Twelve cyanogen bromide peptides were isolated from S-carboxymethylated mitochondrial aspartate aminotransferase and their amino acid sequences were determined. These peptides were purified first by gel filtration on a Sephadex G-75 column, and then by gel filtration on Bio-Gel, or by ion exchange chromatography on a phosphocellulose column in the presence of 8 M urea, or by both methods. Small peptides were purified by paper chromatography. The cyanogen bromide peptides accounted for 367 of the 401 amino acid residues in the subunit of the enzyme. No peptide accounting for the other 34 residues was obtained in a homogeneous state, but peptide mixtures containing this particular peptide were analyzed by various procedures including Edman degradation and digestion with Staphylococcus aureus protease. The results accounted for all 401 amino acid residues.
 ...
PMID:Complete amino acid sequence of mitochondrial aspartate aminotransferase from pig heart muscle. Cyanogen bromide peptides. 739 Oct 11

Aspartate aminotransferase from Sulfolobus solfataricus (SsAspAT) is an extremely thermophilic and thermostable dimeric enzyme which retains its structure and reaches maximal activity at 100 degrees C. The structural stability of this protein was investigated by coupling isothermally and thermally induced denaturation studies to molecular modeling. Gel filtration analysis indicated that SsAspAT unfolds with an N2 reversible 2D mechanism. In the molecular model, a cluster of hydrophobic residues was shown at the interface between the subunits of SsAspAT and suggested this cluster as a structural feature stabilizing the enzyme quaternary structure. At 25 degrees C, SsAspAT is less resistant to guanidinium chloride-induced denaturation than the cytosolic aspartate aminotransferase from pig heart (cpAspAT), which was chosen as a mesophilic counterpart in the thermodynamic analysis since it shares with SsAspAT the two-state unfolding mechanism. Therefore, in the case of aspartate aminotransferases, thermal stability does not correlate with the stability against chemical denaturants. Isothermal denaturation curves at 25 degrees C and melting profiles recorded in the presence of guanidinium chloride showed that the delta G degrees (H2O) at 25 degrees C of SsAspAT exceeds that of cpAspAT by roughly 15 kJ/mol; the parameter delta n, related to the number of binding sites for the denaturant differentially exposed in unfolded and folded states, is higher for SsAspAT than for cpAspAT; and delta Cp is lower for the thermophilic enzyme than for the mesophilic one by 8 kJ/K.mol. These results are indicative of a less hydrophobic core for SsAspAT than cpAspAT. In agreement with this, the molecular model predicts that some charged side chains are buried in SsAspAT and interact to form an H-bond/ion-pair network.
 ...
PMID:Stability of aspartate aminotransferase from Sulfolobus solfataricus. 915 89

Although liver fatty acid-binding protein (L-FABP) is an important binding site for various hydrophobic ligands in hepatocytes, its in vivo significance is not understood. We have therefore created L-FABP null mice and report here their initial analysis, focusing on the impact of this mutation on hepatic fatty acid binding capacity, lipid composition, and expression of other lipid-binding proteins. Gel-filtered cytosol from L-FABP null liver lacked the main fatty acid binding peak in the fraction that normally comprises both L-FABP and sterol carrier protein-2 (SCP-2). The binding capacity for cis-parinaric acid was decreased >80% in this region. Molar ratios of cholesterol/cholesterol ester, cholesteryl ester/triglyceride, and cholesterol/phospholipid were 2- to 3-fold greater, reflecting up to 3-fold absolute increases in specific lipid classes in the order cholesterol > cholesterol esters > phospholipids. In contrast, the liver pool sizes of nonesterified fatty acids and triglycerides were not altered. However, hepatic deposition of a bolus of intravenously injected [14C]oleate was markedly reduced, showing altered lipid pool turnover. An increase of approximately 75% of soluble SCP-2 but little or no change of other soluble (glutathione S-transferase, albumin) and membrane (fatty acid transport protein, CD36, aspartate aminotransferase, caveolin) fatty acid transporters was measured. These results (i) provide for the first time a quantitative assessment of the contribution of L-FABP to cytosolic fatty acid binding capacity, (ii) establish L-FABP as an important determinant of hepatic lipid composition and turnover, and (iii) suggest that SCP-2 contributes to the accumulation of cholesterol in L-FABP null liver.
 ...
PMID:Decreased liver fatty acid binding capacity and altered liver lipid distribution in mice lacking the liver fatty acid-binding protein gene. 1267 Sep 56

The somatic hybrids of Glycine max (L)Merr.-Nicotiana glauca Grah. exhibited a preferential loss of N. glauca chromosomes. When protoplasts from such hybrid cells were 'back fused' twice to N. glauca protoplasts, a considerable increase in stability of the N. glauca chromosomes was observed. Gel electrophoresis studies of aspartate aminotransferase showed that the chromosome(s) responsible for this enzyme was stabilized in the 'back fused' hybrid cell lines. The data suggest that the 'back fusion' technique described in this study might aid in stabilizing somatic hybrids.
...
PMID:Chromosome and isoenzyme studies on cells derived from protoplast fusion of Nicotiana glauca with glycine max-Nicotiana glauca cell hybrids. 2430 Nov 48


1 2 Next >>