Disease relevance of CASPAT

• cDNA cloning and expression of pig cytosolic aspartate aminotransferase in Escherichia coli: amino-terminal heterogeneity of expressed products and lack of its correlation with enzyme function [1].

High impact information on CASPAT

• Its relatively weak activity against Asp is due to lack of an arginine residue corresponding to Arg(292)* (where the asterisk indicates that this is a residues supplied by the other subunit of the dimer) in pig cytosolic aspartate aminotransferase [2].
• A notable feature of porcine cytosolic aspartate aminotransferase is the closure of the active site cleft by a mobile amino-terminal segment (residues 15-40) upon binding substrate [3].
• Functional roles of valine 37 and glycine 38 in the mobile loop of porcine cytosolic aspartate aminotransferase [4].
• The pyridoxal form of the alpha subform of cytosolic aspartate aminotransferase (EC 2.6.1.1) is fully active and binds pyridoxal 5'-phosphate via an aldimine formation with Lys-258 whereas the gamma subform is virtually inactive and lacks the aldimine linkage [5].
• Studies of 6-fluoropyridoxal and 6-fluoropyridoxamine 5'-phosphates in cytosolic aspartate aminotransferase [6].

Biological context of CASPAT

• Non-enzymatic glycosylation (or glycation) and inhibition of the pig heart cytosolic aspartate aminotransferase by glyceraldehyde 3-phosphate [7].
• Partial amino-acid sequence and cysteine reactivities of cytosolic aspartate aminotransferase from horse heart [8].

Anatomical context of CASPAT

• It was found that, in the rat heart muscle, c-AAT reaction product was present as a linear structure parallel to the muscle fiber and along the sarcolemma [9].
• Under the same experimental conditions, the c-AAT was localized in each individual hepatocyte by both monoclonal and polyclonal antibodies [10].
• The rabbit antiserum and mouse monoclonal hybridoma antibody against porcine cytosolic aspartate aminotransferase (c-AAT) (or cytosolic glutamic oxaloacetic transaminase (c-GOT)) were produced and compared for the localization of c-AAT in rat liver [10].

Associations of CASPAT with chemical compounds

• The apoenzyme form of cytosolic aspartate aminotransferase of pig hearts was allowed to react at room temperature with 1 equiv of pyridoxal 5'-sulfate [11].
• Reaction of N-bromosuccinimide with pig heart cytosolic aspartate aminotransferase led to loss of the enzymatic activity [12].
• Glycated cAAT (500 microM glyceraldehyde for 72h at 37 degrees C) increased the T(0.5) (temperature at which 50% denaturation occurs) and the Gibbs free energy barrier (DeltaG) for denaturation [13].
• Carnosine enhanced the thermal unfolding of glycated cAAT as evidenced by a decreased T(0.5) and a lowered Gibbs free energy barrier [13].
• It inactivates pig heart cytosolic aspartate aminotransferase and inhibits aspartate ammonia-lyase by competing with aspartate (Ki/Km 0.23) [14].

Other interactions of CASPAT

• Aspartate aminotransferase from S. solfataricus is cleaved at residue 28 by thermolysin and residues 32 and 33 by trypsin; analogously, pig heart cytosolic aspartate aminotransferase is cleaved at residues 19 and 25 [Iriarte, A., Hubert, E., Kraft, K. & Martinez-Carrion, M. (1984) J. Biol. Chem. 259, 723-728] by trypsin [15].

Analytical, diagnostic and therapeutic context of CASPAT

• A convenient method, based on high-performance Liquid chromatography (HPLC) is described for the analysis of multiple forms of cytosolic aspartate aminotransferase [16].
• We observed that acrolein cross-linked cAAT subunits as evidenced by the presence of high molecular weight bands following SDS-PAGE [17].

References