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

Zymograms of the aspartate aminotransferase (AAT, EC 2.6.1.1) activity in leaf extracts from Aegilops and Triticum species revealed three AAT zones, denoted according to the decreasing electrophoretic mobility towards the anode as AAT-1, AAT-2 and AAT-3. The AAT activity zymograms of subcellular fractions isolated from T. aestivum seedlings made it possible to establish that the AAT-1 zone is located in the mitochondria, AAT-2 in the chloroplasts and AAT-3 in the cytoplasm. Most of the total AAT activity from wheat leaves arises from the chloroplasts and cytoplasm. The AAT-3 zone exhibited the lowest electrophoretic mobility, but 3 isoenzymes occurring within were the most visibly separated. The occurrence of a single band in this zone at the AAT-3a position (closest to the anode) for the aneuploid CS3ASDt AABBDD line (the absence of long arms of the 3rd pair of homologous chromosomes in the A genome) and at the AAT-3c position for Ae. umbellulata (genome UU), as well as three bands in the whole zone for T. durum (AABB) and T. aestivum (AABBDD) each, made it possible to evaluate the subunit composition of isoenzymes in the AAT-3 zone. The band at the AAT-3a position in the zymogram is formed from bb dimers, AAT-3b from ab and AAT-3c from aa. By comparing the distribution of isoenzyme bands intensities (the result of enzymatic activity) with the mathematical models, the frequencies of the occurrence of the a and b subunits within AAT-3 zone were evaluated. In AAT-3 from T. durum, a and b occurred at the ratio of 0.54:0.46, and in that from T. aestivum - 0.62:0.38, respectively.
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PMID:Genetic control of aspartate aminotransferase isoenzymes in Aegilops and Triticum species. 1552 51

The aim of the present study was to investigate the anti-schistosomal activity of colostral and mature camel milk on Schistosoma mansoni infected mice. Six weeks post infection, mean percentage of protection was detected through the hepatic portal vein. Glutathione-s-transferase (GST), alanine, aspartate transaminase (ALT and AST) and immunoglobulin G (IgG) levels were detected in sera of treated mice before and after infection. Antischistosomal activity of colostral and mature camel milk on Schistosoma mansoni infected mice were 12.81% and 31.60% respectively. The results showed that GST levels in sera of mice fed on colostral and mature camel milk were increased with mean values of 0.070, 0.108, 0.128 and 0.120 in colostral milk groups and 0. 072, 0.085, 0.166 and 0.20 in mature camel milk groups compared with the mice fed on basal diet with means values of 0.070, 0.085, 0.078 and 0.069 before infection and after two, four and six weeks of infection, respectively. On the other hand, there were slight differences on ALT and AST activities. Mice treated with colostral and mature milk (200 microl/day) showed an immunostimulatory effect by inducing IgG titers against soluble worm antigen preparation (SWAP) compared with control. Nevertheless, the difference was not considered significant (0.31 +/- 0.1) for colostrum (0.34 +/- 0.1) and for mature milk, as compared to normal control (0.2 +/- 0.04). Two, four and six weeks post infection, IgG level showed no significant change in sera from mice treated with colostral and mature milk as compared to control. In conclusion, colostral and mature camel milk showed an immuno-modualatory effect in normal healthy mice by inducing IgG and GST levels before and after infection with Schistosoma mansoni. Colostral and mature camel milk have a protective response against schistosomiasis.
Asia Pac J Clin Nutr 2005
PMID:Anti-schistosomal activity of colostral and mature camel milk on Schistosoma mansoni infected mice. 1632 52

In this paper, we report the identification of genes from pine (PpAAT), Arabidopsis (AtAAT) and rice (OsAAT) encoding a novel class of aspartate aminotransferase (AAT, EC 2.6.1.1) in plants. The enzyme is unrelated to other eukaryotic AATs from plants and animals but similar to bacterial enzymes. Phylogenetic analysis indicates that this prokaryotic-type AAT is closely related to cyanobacterial enzymes, suggesting it might have an endosymbiotic origin. Interestingly, most of the essential residues involved in the interaction with the substrate and the attachment of pyridoxal phosphate cofactor in the active site of the enzyme were conserved in the deduced polypeptide. The polypeptide is processed in planta to a mature subunit of 45 kDa that is immunologically distinct from the cytosolic, mitochondrial and chloroplastic isoforms of AAT previously characterized in plants. Functional expression of PpAAT sequences in Escherichia coli showed that the processed precursor is assembled into a catalytically active homodimeric holoenzyme that is strictly specific for aspartate. These atypical genes are predominantly expressed in green tissues of pine, Arabidopsis and rice, suggesting a key role of this AAT in nitrogen metabolism associated with photosynthetic activity. Moreover, immunological analyses revealed that the plant prokaryotic-type AAT is a nuclear-encoded chloroplast protein. This implies that two plastidic AAT co-exist in plants: a eukaryotic type previously characterized and the prokaryotic type described here. The respective roles of these two enzymes in plant amino acid metabolism are discussed.
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PMID:Identification and functional analysis of a prokaryotic-type aspartate aminotransferase: implications for plant amino acid metabolism. 1662 2

Three aspartate aminotransferase isoenzymes were identified from extracts of carrot (Daucus carota L.) cell suspension cultures. These isoenzymes were separated by DEAE chromatography and were analyzed on native gradient polyacrylamide gels. The relative molecular weights of the isoenzymes were 111,000 +/- 5000, 105,000 +/- 5000, and 94,000 +/- 4000 daltons; they were designated forms I, II, and III, respectively. Form I, the predominant form, has been purified to apparent homogeneity (>300-fold) using immunoaffinity chromatography with rabbit anti-pig AAT antibodies. Form I has a subunit size of 43,000 M(r), as determined on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Isoelectric focusing (IEF)-PAGE has resolved three bands at a pl of approximately 5.2. Form I may be composed of subunits of similar molecular weight and different charges, and the three bands with AAT activity on the IEF-PAGE gel are a combination of hetero- and homodimers. Form I has a broad pH optimum of 7.5 to 10.0. K(m) values of 23.6, 2.8, 0.05, and 0.22 millimolar were obtained for glutamate, aspartate, oxaloacetate, and alpha-ketoglutarate, respectively. The mode of action is a ping-pong-bi-bi mechanism.
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PMID:Purification and characterization of aspartate aminotransferase isoenzymes from carrot suspension cultures. 1666 20

Twenty-one monoclonal antibodies were raised against the aspartate aminotransferase-P(2) isoenzyme from root nodules of Lupinus angustifolius [L.] cv Uniharvest. Induction of this isoenzyme is positively correlated with the onset of N(2) fixation in effective root nodules and is associated with the assimilation of ammonia by the plant in the Rhizobium-legume symbiosis. The monoclonal antibodies produced were all of the IgG class, recognized five different epitopes on the protein, and represented greater than 90% of the available epitopes. These epitopes were not unique to lupin nodule aspartate aminotransferase-P(2) but were shown to be present on the enzyme from tobacco leaves and potato. Four of the epitopes were conformational with a fifth epitope recognized by the appropriate monoclonals in both its native and denatured forms. None of the monoclonal antibodies produced reacted with Rhizobium Iupini NZP2257 extracts. Antibodies against two epitopes showed some cross-reaction with the constitutive aspartate aminotransferase-P(1) isoenzyme also found in lupin root nodules. However, affinity of these monoclonals for AAT-P(1) was three orders of magnitude lower than for AAT-P(2). Monoclonals against the other epitopes appeared to be specific for aspartate aminotransferase-P(2).
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PMID:Production and Characterization of Monoclonal Antibodies against Aspartate Aminotransferase-P(2) from Lupin Root Nodules. 1666 41

The purpose of this study was to determine the possible role of serum levels of tissue inhibitors of metalloproteinase-1 (TIMP-1) in the pathogenesis of the progressive inflammation and fibrosis in biliary atresia (BA). Serum concentrations of TIMP-1 were measured in 57 BA patients and 15 healthy controls using commercially available enzyme-linked immunosorbent assays. The mean ages of the BA patients and the controls were 6.1 +/- 0.6 and 6.7 +/- 1.1 years, respectively. The patients were categorized into two groups according to their clinical outcomes: patients with jaundice (total bilirubin > or = 2 mg/dl) and patients without jaundice (total bilirubin < 2 mg/dl). In our study, serum levels of TIMP-1 were significantly higher in the BA patients than in healthy subjects (4.8 +/- 0.4 vs. 3.5 +/- 0.3 ng/ml, respectively; p < 0.05). Additionally, serum levels of TIMP-1 significantly increased in the BA patients with jaundice in comparison to those without jaundice (6.3 +/- 0.7 vs. 3.1 +/- 0.3 ng/ml, respectively; p = 0.001). Patients with persistent jaundice had lower levels of albumin but had greater levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and gamma glutamyl transpeptidase compared with patients without jaundice. Furthermore, patients with portal hypertension (PH) had higher TIMP-1 levels than those without PH (5.3 +/- 0.4 vs. 1.9 +/- 0.3 ng/ml, respectively; p < 0.001). It is concluded that serum levels of TIMP-1 increased in patients with BA. The significant increase in TIMP-1 levels is related to the presence of PH and the severity of jaundice. The elevated TIMP-1 levels may reflect the degree of hepatic fibrosis and development of PH. The data suggest that TIMP-1 may play a role in the pathophysiology of post-Kasai BA.
Asian Pac J Allergy Immunol
PMID:Association of serum levels of tissue inhibitors of metalloproteinase-1 with clinical outcome in children with biliary atresia. 1713 82

Genetic structure of juvenile fish from the populations of the Atlantic salmon Salmo salar inhabiting the rivers of Murmansk oblast, Arkhangelsk oblast, and Karelia, as well as of juveniles from hatcheries was examined at five allozymic loci: aspartate aminotransferase (AAT-4*), isocitrate dehydrogenase (IDHP-3*), iditol dehydrogenase (IDDH-2*), esterase D (ESTD*), and malic enzyme (MEP-2*). High genetic differentiation of both natural and "hatchery" juvenile fish was revealed. It was demonstrated that the gene pool of juveniles at three of the five loci tested was to a considerable degree formed by natural selection. In this case, the role of limiting factor was played by the duration of critical temperature regime in the rivers. The differentiation factors for juveniles from nature were not established, however, their clusterization pattern pointed to a possible role of natural selection in this process.
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PMID:[Selective effect of the duration of the critical temperature period on some allozyme loci of Atlantic salmon Salmo salar L. (Salmonidae)]. 1715 9

Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
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PMID:Crystal structure of Homo sapiens kynureninase. 1730 Jan 76

Homeopathy is considered as one modality for cancer therapy. However, there are only very few clinical reports on the activity of the drugs, as well as in experimental animals. Presently we have evaluated the inhibitory effects of potentized homeopathic preparations against N'-nitrosodiethylamine (NDEA) induced hepatocellular carcinoma in rats as well as 3-methylcholanthrene-induced sarcomas in mice. We have used Ruta, Hydrastis, Lycopodium and Thuja, which are commonly employed in homeopathy for treating cancer. Administration of NDEA in rats resulted in tumor induction in the liver and elevated marker enzymes such as gamma-glutamyl transpeptidase, glutamate pyruvate transaminase, glutamate oxaloacetate transaminase and alkaline phosphatase in the serum and in liver. Concomitant administration of homeopathic drugs retarded the tumor growth and significantly reduced the elevated marker enzymes level as revealed by morphological, biochemical and histopathological evaluation. Out of the four drugs studied, Ruta 200c showed maximum inhibition of liver tumor development. Ruta 200c and phosphorus 1M were found to reduce the incidence of 3-methylcholanthrene-induced sarcomas and also increase the life span of mice harboring the tumours. These studies demonstrate that homeopathic drugs, at ultra low doses, may be able to decrease tumor induction by carcinogen administration. At present we do not know the mechanisms of action of these drugs useful against carcinogenesis.
Asian Pac J Cancer Prev
PMID:Inhibition of chemically induced carcinogenesis by drugs used in homeopathic medicine. 1747 81

Plant aspartate aminotransferase (AAT, EC 2.6.1.1) plays a key role in primary nitrogen assimilation, the transfer of reducing equivalents and the interchanges of carbon and nitrogen pools between subcellular compartments. We investigated the AAT family in conifers using maritime pine as the experimental model. Genes for cytosolic, mitochondrial and two plastidic isoenzymes (eukaryotic- and prokaryotic-types) were identified and their deduced amino acid sequences compared. The primary structure of the eukaryotic-type enzymes is quite well conserved, whereas the prokaryotic-type AAT is highly divergent (15% of identity). These molecular data were confirmed by the absence of immunological cross-reactivity between the two types of native AATs. The mature prokaryotic-type polypeptide was overexpressed in Escherichia coli, and the native enzyme was purified to apparent homogeneity and its molecular properties determined. The fully active recombinant holoenzyme showed highest catalytic activity at 50-60 degrees C and was moderately thermostable, retaining about 50% of its activity after incubation at 70 degrees C for 5-10 min. The presence of pyridoxal 5'-phosphate significantly increased the thermostability of the enzyme. These molecular characteristics were exploited to develop a rapid protocol for the purification of this prokaryotic-type enzyme from pine cotyledons. The results will be useful for studying aspartate and amino acid metabolism in trees.
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PMID:The aspartate aminotransferase family in conifers: biochemical analysis of a prokaryotic-type enzyme from maritime pine. 1754 28


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