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

Calcium stimulated efflux of four enzymes from human rectus abdominis muscle was studied in vitro. The ratio of efflux of creatine kinase (EC2.7.3.2) increased with increasing calcium concentrations reaching a maximum level with 5mM calcium of 1.9 times that in the absence of calcium. Lactate dehydrogenase (EC 1.1.1.27) efflux at this calcium concentration increased to 2.6 times that in the absence of calcium. However, alanine aminotransferase (EC 2.6.1.2) and aspartate aminotransferase (EC 2.6.1.1) showed a slower increase in the rate of efflux in the presence of 5OmM calcium reaching levels of only 1.3 and 1.5 times respectively that in the absence of calcium. These observations suggest that calcium may be involved in augmenting enzyme efflux from human muscle and may therefore be of relevance in the pathogenesis of Duchenne muscular dystrophy.
 ...
PMID:Calcium stimulated enzyme efflux from human skeletal muscle. 740 66

We found a gene homologous to tyrB, which encodes aromatic amino acid aminotransferase (ArAT, EC2.6.1.57) in Escherichia coli, in the genome of Salmonella typhimurium IFO 13245. The S. typhimurium tyrB product consists of 397 amino acid residues. The amino acid sequence shows 87.9% identity with that of E. coli ArAT, but shows lower identity (42.3%) with that of E. coli aspartate aminotransferase (AspAT, EC2.6.1.1). When the S. typhimurium tyrB gene was expressed in an E. coli mutant whose intrinsic tyrB gene had been inactivated, the activity of transaminating tyrosine and phenylalanine could be recovered, indicating that the S. typhimurium tyrB gene product possesses transamination activities similar to those of the E. coli ArAT. Elucidation of the molecular features of a new ArAT may be helpful for structural and functional analyses of ArAT and AspAT with regard to the different but overlapping substrate specificity of the two enzymes.
 ...
PMID:Cloning and characterization of the tyrB gene from Salmonella typhimurium. 880 8