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)

1. Mitochondrial and supernatant aspartate transaminases (EC 2.6.1.1) and supernatant alanine transaminase (EC 2.6.1.2) were purified 89-, 204- and 240-fold respectively, from dolphin muscle. Starch-gel electrophoresis of crude and purified preparations revealed that all three enzymes exist as single forms. 2. K(m) values of alpha-oxoglutarate, alanine, pyruvate and glutamate for the alanine transaminase were 0.45, 8.2, 0.87 and 15mm respectively. For the aspartate transaminases, the K(m) values of alpha-oxoglutarate, aspartate, oxalacetate and glutamate were 0.76, 0.50, 0.10 and 9.4mm respectively, for the mitochondrial form and 0.13, 2.4, 0.06 and 3.2mm respectively, for the supernatant form. 3. In all cases, as the assay pH value was decreased from pH7.3, the K(m) values of the alpha-oxo acids decreased whereas those of the amino acids increased. 4. The apparent equilibrium constants for the aspartate transaminases were independent of pH. These values were 9.2 and 6.8 for the mitochondrial and supernatant forms respectively, where [Formula: see text] 5. Studies of the inhibition of the aspartate transaminases by dicarboxylic acids indicated that these enzymes may be controlled by pools of metabolic intermediates. 6. Three key roles are suggested for the transaminases in the energy metabolism of the diving animal. First, it is believed that a combined action of the transaminases could enhance energy production during hypoxia by providing (a) fumarate from aspartate for the ATP-producing reversal of succinate dehydrogenase, and (b) alpha-oxoglutarate from glutamate for the GTP-producing succinyl thiokinase reaction. Secondly, diving mammals probably accumulate more NADH than other mammals during hypoxia. The aspartate transaminases seem particularly well suited for restoring and maintaining redox balance via the malate-aspartate cycle after aerobic metabolism is resumed. Finally, since the preferred fuel for aerobic work is fat, the combined reactions of the transaminases could be instrumental in providing increased supplies of oxaloacetate for sparking the tricarboxylic acid cycle.
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PMID:Purification and properties of dolphin muscle aspartate and alanine transaminases and thier possible roles in the energy metabolism of diving mammals. 446 40

L-Leucine and its nonmetabolized analogue, 2-aminobicyclo-[2,2,1]heptane-2-carboxylic acid (BCH) activate glutamate dehydrogenase in pancreatic islets, whether the reaction velocity is measured in the direction of glutamate synthesis or glutamate deamination. The rate of glutamate oxidative deamination is increased by ADP and inhibited by 2-ketoglutarate, NH4+ and GTP. The islet homogenate catalyzes the transamination between L-glutamate and either 2-ketoisocaproate or pyruvate, and between 2-ketoglutarate and L-leucine, L-aspartate, L-alanine, L-isoleucine, L-valine, L-norvaline or L-norleucine, but not b (+/-) BCH. The glutamate-aspartate transaminase is preferentially located in mitochondria relative to other transaminases. The parallel effects of L-leucine and BCH on glutamate dehydrogenase and their vastly different abilities to act as transamination partners may account for both analogies and discrepancies in the metabolic and functional responses of the islets to these two branched-chain amino acids.
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PMID:The stimulus-secretion coupling of amino acid-induced insulin release. XI. Kinetics of deamination and transamination reactions. 675 75

The influence of Zn on the acute hepatotoxicity of pyrrolizidine alkaloids (PAs) was determined in male rats. Zinc, 72 mumol/kg as ZnCl2, was administered ip for 3 consecutive days, followed 16 h after the last dose by a single ip injection of purified mixed PAs (80, 120, or 160 mg/kg) obtained from tansy ragwort (Senecio jacobaea). Hepatotoxicity of the PAs was assessed by measuring the activities of plasma glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) and by histological examination of the liver. There was a dose-dependent increase in plasma GOT and GTP 24 h after PA administration, whereas no significant increase of these enzymes was seen after administering Zn alone. The 7-fold increase in plasma GOT and 12-fold increase in GPT after PA (120 mg/kg) were reduced to 2.4- and 2.1-fold, respectively, by Zn pretreatment. The PA-induced liver necrosis was either reduced in severity or abolished by Zn when the PA dose was 80 or 120 mg/kg. These results suggest a protective effect of Zn against PA hepatotoxicity. The protective effect was associated with a marked increase in liver metallothionein and a significant decrease in hepatic cytochrome P-450 content, aminopyrine N-demethylase activity, and in vitro microsomal conversion of the PAs to pyrroles. Liver nonprotein sulfhydryls were unchanged. The possible role of metallothionein in the sequestration of pyrrole metabolites merits further investigation.
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PMID:Protective action of zinc against pyrrolizidine alkaloid-induced hepatotoxicity in rats. 709 90

It is now quite well accepted that laboratory test results are indispensable or of primary significance to accurately diagnose a new patient's disease. Furthermore, most doctors recently find difficulty in appropriately selecting and ordering necessary but not excess laboratory tests and to read and interpret all the given test results correctly. In our hospital the system of the outpatient clinic will be changed basically on a specialty clinic system. In order to operate such a specialty clinic system effectively, it appears quite important to set up a unit to discriminate new unspecified patients properly and to consult them to an appropriate specialty clinic. As a preliminary trial, we opened a new patient clinic in July, 1992. The aim of this clinic is to accurately diagnose the new patients' disease immediately and to send them to the specialty clinic on the day of their first visit. Prior to history taking and physical examination by the attending doctor, the patients are instructed to take a set of laboratory tests. These include urinalysis, chest X-P, ECG, hematological examinations (RBC, WBC, Ht, Hb, PLT and ESR) and biochemical tests (AST, ALT, ALP, gamma GTP, LDH, CPK, Chol, T-Bil, TP, Alb, TG, BUN, Cr, Glu, Na, K, Ca, P and CRP). These results are transferred to the clinic within one hour so that the doctor is able to make the diagnosis effectively and to refer the patients to an appropriate clinic.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Roles of department of laboratory medicine on the new patient clinic]. 828 94

We treated 82 patients of chronic hepatitis using 300 mg. of ursodeoxycholic acid (UDCA) daily and observed them for a mean of 10 mo before and 16 mo after UDCA administration. Seven liver function tests (AST, ALT, ALP, LAP, GTP, Ch-E and T-cholest) were assessed monthly. The values were compared before and after the administration of UDCA. The AST, ALT, LAP and GTP improved significantly in the UDCA treated patients, whereas ALP, Ch-E and T-cholest. did not show any change throughout the study. Amongst the liver function tests that improved, the serum--GTP level, in particular decreased markedly and rapidly in patients treated with UDCA. Although UDCA 600-mg daily was administered in patients who showed lack of improvement with 300-mg UDCA treatment, no significant improvement was obtained. Repeated liver biopsies were carried out in six of the 42 patients in whom liver biopsy had been performed before the administration of UDCA. We detected no histological changes during the UDCA treatment. There were no side effects related to therapy with UDCA. In conclusion, we confirmed that UDCA is a safe and effective drug for treating patients with chronic hepatitis and may help in prevention of progression of the disease, particularly in patients with a high serum--GTP level.
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PMID:Treatment of patients with chronic hepatitis using ursodeoxycholic acid. 829 Nov 25

We cloned the era gene of Francisella tularensis from a plasmid library by heterologous genetic complementation of an Escherichia coli mutant conditionally defective for the production of Era, an essential protein for cell growth. Nucleotide sequence analysis indicated that, in F. tularensis, era constitutes a single gene operon. ORFs aspC and mdh encoding aspartate aminotransferase and malate dehydrogenase, respectively, flank era in F. tularensis. Although classified as Gram-, the flanking regions and the relative location of era in F. tularensis are distinctly different from those of typical Gram- and Gram+ bacteria. Computer analysis of bacterial Era protein sequences identified conserved domains in addition to the common G domains of most GTP-binding proteins.
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PMID:A Francisella tularensis DNA clone complements Escherichia coli defective for the production of Era, an essential Ras-like GTP-binding protein. 916 8

A novel human DNA virus, TTvirus (TTV), was identified from a patient with posttransfusion hepatitis of unknown etiology. It is thought to be a new hepatitis virus, but the clinical significance of this virus is uncertain. We investigated the frequency of TTV viremia by PCR in 39 non-B, non-C hepatitis (NBNC) patients with hepatocellular carcinoma (HCC), and clinical features of these patients. TTV viremia was detected in 20 (51.3%) of 39 NBNC hepatitis patients with HCC. Liver cirrhosis (LC) were found in 11 (55%) of 20 TTV-positive patients and 16 (84%) of 19 TTV-negative patients (p < 0.05). The levels of AST, LDH, LAP, gamma GTP in TTV-positive patients were significantly higher than those in TTV-negative patients (p < 0.05). (AST: 58 +/- 26 vs 42 +/- 23 IU/l, LDH: 468 +/- 127 vs 366 +/- 123 IU/l, LAP: 339 +/- 242 vs 206 +/- 80 IU/l, gamma GTP: 207 +/- 207 vs 105 +/- 107 IU/l) These results suggest clinical differences between TTV-positive and TTV-negative patients in NBNC hepatitis patients with HCC.
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PMID:[Detection of TT virus (TTV) in non-B, non-C hepatitis patients with hepatocellular carcinoma, and clinical features of these patients]. 1039 Oct

GTP hydrolysis by elongation factor Tu (EF-Tu) on the ribosome is induced by codon recognition. The mechanism by which a signal is transmitted from the site of codon-anticodon interaction in the decoding center of the 30S ribosomal subunit to the site of EF-Tu binding on the 50S subunit is not known. Here we examine the role of the tRNA in this process. We have used two RNA fragments, one which contains the anticodon and D hairpin domains (ACD oligomer) derived from tRNA(Phe) and the second which comprises the acceptor stem and T hairpin domains derived from tRNA(Ala) (AST oligomer) that aminoacylates with alanine and forms a ternary complex with EF-Tu. GTP. While the ACD oligomer and the ternary complex containing the Ala-AST oligomer interact with the 30S and 50S A site, respectively, no rapid GTP hydrolysis was observed when both were bound simultaneously. The presence of paromomycin, an aminoglycoside antibiotic that binds to the decoding site and stabilizes codon-anticodon interaction in unfavorable coding situations, did not increase the rate of GTP hydrolysis. These results suggest that codon recognition as such is not sufficient for GTPase activation and that an intact tRNA molecule is required for transmitting the signal created by codon recognition to EF-Tu.
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PMID:Intact aminoacyl-tRNA is required to trigger GTP hydrolysis by elongation factor Tu on the ribosome. 1067 22

Pyruvate has been shown to benefit cellular energy metabolism and to reduce free radical formation. Concerning gastrointestinal side effects of orally administered sodium pyruvate, in this pilot study we investigated the therapeutic effectiveness of sodium pyruvate infusions in patients with alcoholic liver disease (ALD). Fifteen patients with ALD received sodium pyruvate infusions for: (1) 10 days (54-86.4 g pyruvate daily, 150-180 mg/min., 6-8 h); and (2) 15 days (50-54 g daily, 100 mg/min., 6 h). Sodium pyruvate treatment resulted in significantly decreased serum AST (p<0.03), ALT (p<0.03), AP (p<0.004), GGT (p<0.05), and total bilirubin (p<0.04). Improvement of liver function was also evident from the significantly decreased Combined Clinical and Laboratory Index (from 6.50+/-0.71, to 3.92+/-0.84, p<0.001), and Liver Damage Score (from 3.83+/-0.71 to 2.75+/-0.58, p<0.01). The two therapy schedules used showed similar results. Unchanged serum pyruvate, lactate, and glucose confirmed the good utilization of pyruvate. Tolerance of sodium pyruvate treatment was very good in 26.09% and good in 68.94% of the observations. Our results showed good therapeutic effectiveness and good tolerance of sodium pyruvate infusions in patients with ALD. This is possibly due to the rapid gain of ATP and GTP, required to redress defective cells, and to antioxidant action of pyruvate.
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PMID:Sodium pyruvate infusions in patients with alcoholic liver disease. Preliminary report. 1168 47

To determine the difference between alcoholic hepatitis (AH) and non-alcoholic steatohepatitis (NASH) in Japan, six patients with Ah and four patients with NASH, recently treated at our institute, were clinically and pathologically evaluated. Clinical features of the diseases differed: in NASH patients, mean age was higher, mean body mass index much higher, and the prevalence of diabetes mellitus was higher than in AH patients. The patients with NASH presented with unremarkable symptoms and signs. Abnormalities in liver function tests including prothrombin time and choline esterase were mild in NASH patients, except for the indocyanine green test. They had ALT-dominant hypertransaminasemia. AST, ALT and gamma GTP did not normalize as promptly as in AH patients after admission. However, there was no significant difference in the histological grade of fibrosis, inflammation or hepatocytic metamorphosis between NASH and AH patients. Stellate-form fibrosis was characteristic of AH, whereas pericellular and perivenular types were common in NASH patients. Focal cell necrosis was rather intense, and fatty deposits prominent, in NASH patients. However, it was difficult to histopathologically discriminate between NASH and AH patients. If AH is histologically suspected in non-alcoholic patients, the possibility of NASH should always be considered. Furthermore, even in patients with suspected simple fatty liver, a liver biopsy should be performed, especially in cases with prolonged abnormal liver function findings.
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PMID:Clinical and pathological differences between alcoholic hepatitis and non-alcoholic steatohepatitis. 1268 23


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