Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.6.1.1 (aspartate aminotransferase)
21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influences of low root temperature on soybeans (Glycine max [L.] Merr. cv. Wells) were studied by germinating and maintaining plants at root temperatures of 13 and 20 C through maturity. At 42 days from the beginning of imbibition, 13 and 20 C plants were switched to 20 and 13 C, respectively. Plants were harvested after 63 days. Control plants (13 C) did not nodulate, whereas those switched to 20 C did and at harvest had C(2)H(2) reduction rates of 0.2 micromoles per minute per plant. Rates of C(2)H(2) reduction decreased rapidly in plants switched from 20 to 13 C; however, after 2 days, rates recovered to original levels (0.8 micromoles per minute per plant) and then began a slow decline until harvest. Arrhenius plots of C(2)H(2) reduction by whole plants indicated a large increase in the energy of activation below the inflection at 15 C. Highest C(2)H(2) reduction rates (1.6 micromoles per minute per plant) were at 58 days for the 20 C control. Root respiration rates followed much the same pattern as C(2)H(2) reduction in the 20 C control and transferred plants. At harvest, roots from 13 C-treated plants had the highest activities for malate dehydrogenase, glutamate oxaloacetate transaminase, and phosphoenolpyruvate carboxylase. Roots from transferred plants had intermediate activities and those from the 20 C treatment the lowest activities. Newly formed nodules from plants switched from 13 to 20 C had much higher glutamate dehydrogenase than glutamine synthetase activity.Photosynthetic rates on a leaf area basis were about three times as high in the 20 C control as compared to 13 C control plants. Photosynthetic rates of plants switched from 20 to 13 C decreased to less than half the original rate within 2 days. Photosynthetic rates of plants switched from 13 to 20 C recovered to rates near those of the 20 C control plants within 2 weeks. All leaf enzymes assayed at harvest, with the exception of nitrate reductase, were highest in activity in the 20 C control plants.
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PMID:Low root temperature effects on soybean nitrogen metabolism and photosynthesis. 1666 Aug 44

Amide and ureide biogenic enzymes were measured in the plant fraction of soybean (Glycine max) nodules during the period 11 to 23 days after inoculation with Rhizobium japonicum (USDA 3I1b142). Enzymes involved in the initial assimilation of ammonia, i.e. glutamine synthetase, glutamate synthase, and aspartate aminotransferase, showed substantial increases in their specific activities over the time course. These increases paralleled the induction of nitrogenase activity in the bacteroid and leghemoglobin synthesis in the plant fraction. The specific activity of asparagine synthetase, however, showed a rapid decline after an initial increase in specific activity. Following the initial increases in the ammonia assimilatory enzymes, there was an increase in the activity of 5-phosphoribosylpyrophosphate amidotransferase, the enzyme which catalyzes the first committed step of de novo purine biosynthesis. This was followed by a dramatic increase in the purine oxidative enzymes, xanthine dehydrogenase and uricase. Smaller increases were observed in the activities of enzymes associated with the supply of metabolites to the purine biosynthetic pathway: phosphoglycerate dehydrogenase, serine hydroxymethylase, and methylene tetrahydrofolate dehydrogenase.The concentration of asparagine in the plant fraction decreased at the same time as the observed decrease in asparagine synthetase activity. This was followed by a recovery in plant fraction levels of asparagine in the presence of a continuing fall in the glutamine concentration and continued low asparagine synthetase activity.The data presented are consistent with initial assimilation of ammonia into glutamine and aspartate, which are metabolized by an elevation of endogenous purine biosynthetic enzymes, and then, by the induction of a specific group of purine oxidative enzymes, directed to allantoic acid production.
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PMID:Enzymes of amide and ureide biogenesis in developing soybean nodules. 1666 97

The distribution of organelles and associated enzymes between cells containing bacteroids and uninfected cells from nodules of Glycine max L. Merr. cv Amsoy 71 was investigated by separation of protoplasts on a sucrose step-gradient. Infected protoplasts were much larger, irregular in shape, and more dense than uninfected protoplasts. The peroxisomal enzymes, uricase and catalase, were present at much higher specific activity in the uninfected cell fraction. Allantoinase, an enzyme of the endoplasmic reticulum, had a greater specific activity in the uninfected cell fraction. Several enzymes whose products are required for purine biosynthesis, including phosphoglycerate dehydrogenase, aspartate aminotransferase, 6-phosphogluconate dehydrogenase, and glucose-6-phosphate dehydrogenase, exhibited a higher specific activity in the uninfected cell fraction. Isozymes of aspartate aminotransferase were separated on native gels and located by an activity stain. The soluble isozyme was predominantly found in the uninfected cell fraction. These data suggest that peroxisomes, containing uricase and catalase for conversion of uric acid to allantoin, are present only in the uninfected cells of soybean nodules. The uninfected cells also appear to be the site of the allantoinase reaction.
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PMID:Isolation and characterization of infected and uninfected cells from soybean nodules : role of uninfected cells in ureide synthesis. 1666 21

Aspartate aminotransferase (glutamate-oxalacetate transaminase) was partially purified from extracts of germinating seeds of peanut (Arachis hypogaea), honey locust (Gleditsia triacanthos), soybean (Glycine max), and Sophora japonica. The ability of these enzyme preparations, as well as aspartate aminotransferase purified from pig heart cytosol, to use 4-substituted glutamic acids as amino group donors and their corresponding 2-oxo acids as amino group acceptors in the aminotransferase reaction was measured. All 4-substituted glutamic acid analogs tested were poorer substrates than was glutamate or 2-oxoglutarate. 2-Oxo-4-methyleneglutarate was least effective (lowest relative V(m)/K(m)) as a substrate for the enzyme from peanuts and honey locust, which are the two species studied that accumulate 4-methyleneglutamic acid and 4-methyleneglutamine. Of the different aminotransferases tested, the enzyme from honey locust was the least active with 2-oxo-4-hydroxy-4-methylglutarate, the corresponding amino acid of which also accumulates in that species. These results suggest that transamination of 2-oxo-4-substituted glutaric acids is not involved in the biosynthesis of the corresponding 4-substituted glutamic acids in these species. Rather, accumulation of certain 4-substituted glutamic acids in these instances may be, in part, the result of the inefficacy of their transamination by aspartate aminotransferase.
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PMID:Specificity of aspartate aminotransferases from leguminous plants for 4-substituted glutamic acids. 1666 74

TATA-binding protein-associated factor 1 (TAF1) is an essential component of the general transcription factor IID (TFIID), which nucleates assembly of the preinitiation complex for transcription by RNA polymerase II. TATA-binding protein and TAF1.TAF2 heterodimers are the only components of TFIID shown to bind specific DNA sequences (the TATA box and initiator, respectively), raising the question of how TFIID localizes to gene promoters that lack binding sites for these proteins. Here we demonstrate that Drosophila TAF1 protein isoforms TAF1-2 and TAF1-4 directly bind DNA independently of TAF2. DNA binding by TAF1 isoforms is mediated by cooperative interactions of two identical AT-hook motifs, one of which is encoded by an alternatively spliced exon. Electrophoretic mobility shift assays revealed that TAF1-2 bound the minor groove of adenine-thymine-rich DNA with a preference for the sequence AAT. Alanine-scanning mutagenesis of the alternatively spliced AT-hook indicated that Lys and Arg residues made essential DNA contacts, whereas Gly and Pro residues within the Arg-Gly-Arg-Pro core sequence were less important for DNA binding, suggesting that AT-hooks are more divergent than previously predicted. TAF1-2 bound with variable affinity to the transcription start site of several Drosophila genes, and binding to the hsp70 promoter was reduced by mutation of a single base pair at the transcription start site. Collectively, these data indicate that AT-hooks serve to anchor TAF1 isoforms to the minor groove of adenine-thymine-rich Drosophila gene promoters and suggest a model in which regulated expression of TAF1 isoforms by alternative splicing contributes to gene-specific transcription.
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PMID:DNA binding properties of TAF1 isoforms with two AT-hooks. 1689 81

L-colitose is a 3,6-dideoxysugar found in the O-antigens of some Gram-negative bacteria such as Escherichia coli and in marine bacteria such as Pseudoalteromonas tetraodonis. The focus of this investigation, GDP-4-keto-6-deoxy-D-mannose-3-dehydratase, catalyzes the third step in colitose production, which is the removal of the hydroxyl group at C3' of GDP-4-keto-6-deoxymannose. It is an especially intriguing PLP-dependent enzyme in that it acts as both a transaminase and a dehydratase. Here we present the first X-ray structure of this enzyme isolated from E. coli Strain 5a, type O55:H7. The two subunits of the protein form a tight dimer with a buried surface area of approximately 5000 A2. This is a characteristic feature of the aspartate aminotransferase superfamily. Although the PLP-binding pocket is formed primarily by one subunit, there is a loop, delineated by Phe 240 to Glu 253 in the second subunit, that completes the active site architecture. The hydrated form of PLP was observed in one of the enzyme/cofactor complexes described here. Amino acid residues involved in anchoring the cofactor to the protein include Gly 56, Ser 57, Asp 159, Glu 162, and Ser 183 from one subunit and Asn 248 from the second monomer. In the second enzyme/cofactor complex reported, a glutamate ketimine intermediate was found trapped in the active site. Taken together, these two structures, along with previously reported biochemical data, support the role of His 188 as the active site base required for catalysis.
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PMID:The structure of GDP-4-keto-6-deoxy-D-mannose-3-dehydratase: a unique coenzyme B6-dependent enzyme. 1694 43

A variant strain of rabbit hemorrhagic disease virus, designated "whn-1", was isolated and identified in China. The virus lacked haemagglutinating activity at 25, 37 and 4 degrees C, respectively, and gave negative results in the HAT after two passages in experimentally infected rabbits, but gave positive results in Agar Diffusion Reaction (ADR) and Counter Immunoelectrophoresis (CIE). Using electron microscopy, negatively stained particles of the RHDV isolate showed that the virions was approximately 35 nm in diameter. The capsid protein VP60 gene of whn-1 strain was cloned into pMD18-T vector by RT-PCR assays and sequenced. The obtained VP60 gene sequence has been submitted to GenBank with the accession number: DQ069280. The whole VP60 gene of whn-1 was 1740 nt in size and encodes 579 aa. Alignment with other 16 strains of RHDV in the world, including such "RHDVa" strains as France 99-05, France-Reu-00, Germany-Triptis and ChinaTP, in addition to RCV and EBHSV, showed that the homology of RHDV strains were 90.0-98.0% for nucleotide sequence, 94.3-99.0% for amino acid sequence, respectively. The results indicated that the sequences of VP60 gene of different RHDV isolates, including non-haemagglutinating whn-1 strain and low-haemagglutinating Rainham strain, were relatively highly homologous, and the major variant amino acid were located within region C (301-328 aa) and region E(344-434 aa), which were specific to "RHDVa" strains. Moreover, the molecular characterisation of VP60 protein of RHDV whn-1 strain, such as Hydrophilicity plot, Flexible regions, Antigenic index, etc., were compared with reference RHDV strains of Spanish-AST/89, France-99-5 and UK-Rainham in this article. From the experiment, it's concluded that, the "whn-1" strain is probably an antigenic variant of "RHDVa", and the 3 amino acids of Phe (304), Ala (305), Ser (309), and 5 amino acids of Gly (359), Asn (365), Ala (369), Ala (370), Asn (386), located in P2 region in the VP60 protein, probably played an important role in the haemagglutination activity.
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PMID:Isolation and identification of a non-haemagglutinating strain of rabbit hemorrhagic disease virus from China and sequence analysis for the VP60 Gene. 1770 93

Whole-genome sequencing of the soybean (Glycine max (L.) Merr. 'Williams 82') has made it important to integrate its physical and genetic maps. To facilitate this integration of maps, we screened 3290 microsatellites (SSRs) identified from BAC end sequences of clones comprising the 'Williams 82' physical map. SSRs were screened against 3 mapping populations. We found the AAT and ACT motifs produced the greatest frequency of length polymorphisms, ranging from 17.2% to 32.3% and from 11.8% to 33.3%, respectively. Other useful motifs include the dinucleotide repeats AG, AT, and AG, with frequency of length polymorphisms ranging from 11.2% to 18.4% (AT), 12.4% to 20.6% (AG), and 11.3% to 16.4% (GT). Repeat lengths less than 16 bp were generally less useful than repeat lengths of 40-60 bp. Two hundred and sixty-five SSRs were genetically mapped in at least one population. Of the 265 mapped SSRs, 60 came from BAC singletons not yet placed into contigs of the physical map. One hundred and ten originated in BACs located in contigs for which no genetic map location was previously known. Ninety-five SSRs came from BACs within contigs for which one or more other BACs had already been mapped. For these fingerprinted contigs (FPC) a high percentage of the mapped markers showed inconsistent map locations. A strategy is introduced by which physical and genetic map inconsistencies can be resolved using the preliminary 4x assembly of the whole genome sequence of soybean.
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PMID:Microsatellite discovery from BAC end sequences and genetic mapping to anchor the soybean physical and genetic maps. 1835 65

D-Galactosamine (GalN) induces acute hepatitis in experimental animals and this hepatitis has been shown to be suppressed by preceding ingestion of amino acids such as Gly, L-Ser, and L-Gln. However, little is known about the mechanism of its action. The present study shows for the first time that IL-18 reduction is involved in the suppressive actions of L-Gln and L-Ser on GalN-induced hepatitis. Elevation of IL-18 mRNA expression in liver and its concentration in serum in GalN-treated rats were found to be suppressed by preceding ingestion of 10% L-Gln- or 10% L-Ser diets, and resulted in the attenuation of the increase in serum transaminase (ALT and AST) activities, indexes of hepatic injury. These results suggest that suppressive effects of some dietary amino acids on the GalN-induced hepatitis are mediated by IL-18 reduction.
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PMID:L-Gln and L-Ser suppress the D-galactosamine-induced IL-18 expression and hepatitis. 1851 57

The genome region encoding the RNA-dependent RNA polymerase 3CD-like precursor from rabbit hemorrhagic disease virus (RHDV) (isolate AST/89) was cloned and expressed in Escherichia coli using polyhistidine fusion-based vectors. The full-length recombinant 3CD-like precursor polypeptide could not be purified as a consequence of its autoproteolytic processing. A Cys-->Gly substitution of the 3C-like catalytic cysteine (C1212) impeded the cleavage and allowed the purification of the precursor at high yields using a polyhistidine fusion expression vector. Equimolar amounts of purified recombinant precursor (C1212G mutant) and mature 3D-like polymerase showed significant activity differences in genome-linked protein (VPg) uridylylation and RNA polymerization using in vitro assays. The data indicated that the precursor was more active than the mature polymerase in catalysing RHDV VPg uridylylation, whereas the latter enzyme form had higher activity than its precursor in RNA polymerization in vitro assays using a heteropolymeric RNA template.
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PMID:Functional differences between precursor and mature forms of the RNA-dependent RNA polymerase from rabbit hemorrhagic disease virus. 1943 53


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