Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
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Gene/Protein
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Target Concepts:
Gene/Protein
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Query: EC:2.6.1.2 (
alanine aminotransferase
)
26,722
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Alanine aminotransferase (AlaAT,
EC 2.6.1.2
) and
glycine aminotransferase
(GlyAT,
EC 2.6.1.4
), two different enzymes catalyzing transamination reactions with L-alanine as the amino-acid substrate, were examined in maize in which alanine participates substantially in nitrogen transport. Preparative PAGE of a partially purified preparation of aminotransferases from maize leaves gave 6 fractions differing in electrophoretic mobility. The fastest migrating fraction I represents AlaAT specific for L-alanine as amino donor and 2-oxoglutarate as amino acceptor. The remaining fractions showed three aminotransferase activities: L-alanine-2-oxoglutarate, L-alanine-glyoxylate and L-glutamate-glyoxylate. By means of molecular sieving on Zorbax SE-250 two groups of enzymes were distinguished in the PAGE fractions: of about 100 kDa and 50 kDa. Molecular mass of 104 kDa was ascribed to AlaAT in fraction I, while the molecular mass of the three enzymatic activities in 3 fractions of the low electrophoretic mobility was about 50 kDa. The response of these fractions to: aminooxyacetate, 3-chloro-L-alanine and competing amino acids prompted us to suggest that five out of the six preparative PAGE fractions represented GlyAT isoforms, differing from each other by the L-glutamate-glyoxylate:L-alanine-glyoxylate:L-alanine-2-oxoglutarate activity ratio.
...
PMID:Alanine aminotransferase and glycine aminotransferase from maize (Zea mays L.) leaves. 1054 44
As glutamate and ammonia play a pivotal role in nitrogen homeostasis, their production is mediated by various enzymes that are widespread in living organisms. Here, we report on an effective electrophoretic method to monitor these enzymes. The in gel activity visualization is based on the interaction of the products, glutamate and ammonia, with glutamate dehydrogenase (GDH, EC: 1.4.1.2) in the presence of either phenazine methosulfate (PMS) or 2,6-dichloroindophenol (DCIP) and iodonitrotetrazolium (INT). The intensity of the activity bands was dependent on the amount of proteins loaded, the incubation time and the concentration of the respective substrates. The following enzymes were readily identified: glutaminase (EC: 3.5.1.2),
alanine transaminase
(EC: 2.6.1.2), aspartate transaminase (EC: 2.6.1.1),
glycine transaminase
(EC: 2.6.1.4), ornithine oxoacid aminotransferase (EC: 2.6.1.13), and carbamoyl phosphate synthase I (EC: 6.3.4.16). The specificity of the activity band was confirmed by high pressure liquid chromatography (HPLC) following incubation of the excised band with the corresponding substrates. These bands are amenable to further molecular characterization by a variety of analytical methods. This electrophoretic technology provides a powerful tool to screen these enzymes that contribute to nitrogen homeostasis in Pseudomonas fluorescens and possibly in other microbial systems.
...
PMID:A blue native polyacrylamide gel electrophoretic technology to probe the functional proteomics mediating nitrogen homeostasis in Pseudomonas fluorescens. 2259 84
Four homologues of
alanine aminotransferase
have been isolated from shoots of wheat seedlings and purified by saline precipitation, gel filtration, preparative electrophoresis and anion exchange chromatography on Protein-Pak Q 8HR column attached to HPLC. Alanine aminotransferase 1 (AlaAT1) and 2 (AlaAT2) were purified 303- and 452-fold, respectively, whereas l-glutamate: glyoxylate aminotransferase 1 (GGAT1) and 2 (GGAT2) were purified 485- and 440-fold, respectively. Consistent inhibition of AlaAT (
EC 2.6.1.2
) and GGAT (
EC 2.6.1.4
) activities by p-hydroxymercuribenzoate points on participation of cysteine residues in the enzyme activity. The molecular weight of AlaAT1 and AlaAT2 was estimated to be 65kDa and both of them are monomers in native state. Nonsignificant differences between K(m) using alanine as substrate and catalytic efficiency (k(cat)/K(m)) for l-alanine in reaction with 2-oxoglutarate indicate comparable kinetic constants for AlaAT1 and AlaAT2. Similar kinetic constants for l-alanine in reaction with 2-oxoglutarate and for l-glutamate in reaction with pyruvate for all four homologues suggest equally efficient reaction in both forward and reverse directions. GGAT1 and GGAT2 were able to catalyze transamination between l-glutamate and glyoxylate, l-alanine and glyoxylate and reverse reactions between glycine and 2-oxoglutarate or pyruvate. Both GGATs also consisted of a single subunit with molecular weight of about 50kDa. The estimated K(m) for GGAT1 (3.22M) and GGAT2 (1.27M) using l-glutamate as substrate was lower in transamination with glyoxylate than with pyruvate (9.52 and 9.09mM, respectively). Moreover, distinctively higher values of catalytic efficiency for l-glutamate in reaction with glyoxylate than for l-glutamate in reaction with pyruvate confirm involvement of these homologues into photorespiratory metabolism.
...
PMID:Biochemical characterization and kinetic properties of alanine aminotransferase homologues partially purified from wheat (Triticum aestivum L.). 2286 64
