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At least 397 records · Page 22Linked to original sources
PubMed2002

Systemic administration of 1R,4S-4-amino-cyclopent-2-ene-carboxylic acid, a reversible inhibitor of GABA transaminase, blocks expression of conditioned place preference to cocaine and nicotine in rats.

We examined the effect of 1R,4S-4-amino-cyclopent-2-ene-carboxylic acid (ACC), a reversible inhibitor of GABA transaminase, on the expression of conditioned place preference response to cocaine and nicotine in rats. Cocaine (20 mg/kg i.p.) and nicotine (0.4 mg/kg s.c.), but not vehicle or 300 mg/kg i.p. of ACC, produced a significant conditioned place preference response. Pretreatment of animals with 300 and 75 mg/kg i.p. of ACC significantly attenuated the expression of the cocaine- and nicotine-induced conditioned place preference responses, respectively. These results are the first to suggest that reversible inhibition of GABA transaminase may be useful in blocking cue-induced relapse to nicotine and cocaine.

4-Aminobutyrate Transaminase↗
PubMed1993

Purification of glutamine transaminase K/cysteine conjugate beta-lyase from rat renal cytosol based on hydrophobic interaction HPLC and gel permeation FPLC.

Cysteine conjugate beta-lyase (beta-lyase, EC 4.4.1.13) was purified to homogeneity from rat renal cytosol using a new and highly efficient method, based on C3-hydrophobic interaction (HI) high-performance liquid chromatography (HPLC) in combination with gel permeation fast protein liquid chromatography. The purity of the enzyme was judged from SDS-PAGE and C18-reversed-phase HPLC. The beta-lyase was estimated to be a homodimer consisting of a 47,400-Da subunit with absorption maxima at 280 and 420-430 nm. The specific activity of the purified beta-lyase toward S-(1,2-dichlorovinyl)-L-cysteine (1,2-DCVC) in the presence of alpha-keto-gamma-methiolbutyric acid (KMB) was 6.4 mumol/min/mg protein, which is by far the highest value so far reported. Kinetic analysis of 1,2-DCVC metabolism by the enzyme in the presence of KMB gave Km and Vmax values of 0.33 mM and 8.4 mumol/min/mg protein, respectively. No significant activity of the purified enzyme was detectable with S-2-benzothiazolyl-L-cysteine up to 2 mM. The purified enzyme also had glutamine transaminase K activity (EC 2.6.1.64) as assayed with phenylalanine and KMB as substrates. This specific activity was 16.0 mumol/min/mg. Amino acid analysis of the purified beta-lyase was carried out and was found to be closely similar to the amino acid composition of five other pyridoxal phosphate (PLP)-containing amino acid amino-transferases. This suggests that glutamine transaminase K/cysteine conjugate beta-lyase is a typical member of the PLP-containing aminotransferase group.

Amino Acids↗
PubMed1984

Localization of a gene which complements branched-chain amino acid transaminase deficiency to the short arm of human chromosome 12.

A human X Chinese hamster somatic cell hybrid (J1) containing only one human chromosome (number 11) does not express branched-chain amino acid transaminase and, therefore, cannot grow if the branched-alpha-keto acids are substituted for the branched-chain amino acids in the growth medium. J1 cells, which are glycine auxotrophs (Gly-A), were fused with normal human lymphocytes and the resulting hybrids selectively isolated in glycine-free medium. A total of 16 primary and 46 secondary clones were analyzed for isozymic and nutritional markers. Cytogenetic analysis with chromosome banding was also performed on selected hybrid clones. The results provide evidence that branched-chain amino acid transaminase is syntenic with lactic dehydrogenase B and is located on the short arm of human chromosome 12.

Animals↗
PubMed1988

Guillain-Barré syndrome and serum activities of gamma-glutamyltransferase and glutamic-pyruvic transaminase.

Objective laboratory indicators of alcohol consumption (mean corpuscular volume and serum glutamic-pyruvic transaminase (GPT), glutamyltransferase (gamma-GT), and glutamic-oxaloacetic transaminase (GOT] were measured in 18 patients with Guillain-Barré syndrome (GBS) and 710 control patients. All of the indicators examined were more frequently found to be pathological in GBS patients, reaching significance for gamma-GT and GPT. Some explanations for this result are discussed. It is concluded that alcohol consumption may be a risk factor for GBS.

Adolescent↗
PubMed1986

Comparison of DNA damage in various tissues, myelosuppression and serum levels of transaminases and bilirubin in tumor-bearing female Sprague-Dawley rats treated with 1-(2-hydroxyethyl)-3-(2-chloroethyl)-3-nitrosourea (HECNU).

Female Sprague-Dawley rats bearing methylnitrosourea-induced mammary carcinomas were treated with 100 mumol 1-(2-hydroxyethyl)-3-(2-chloroethyl)-3-nitrosourea (HECNU)/kg to investigate the time course of DNA-DNA interstrand cross-linking (DNA-XL) as measured by alkaline elution in tumor, bone marrow and liver cells. The inhibition of bone marrow stem cell colony formation in culture (CFU-C) and in spleens of lethally irradiated mice (CFU-S), serum transaminase levels and total bilirubin were concomitantly determined. All parameters were evaluated at different times from 4 to 72 h after treatment. The highest amounts of DNA-XL were found in tumor cells, peaking at 24 h after treatment. A parallel increase was observed in bone marrow cells up to 16 h with a subsequent rapid decrease to about one-third of DNA-XL in tumor cells after 72 h. Concomitantly, CFU-C and CFU-S were suppressed, the nadir being at 24 h after treatment. In liver cells, however, constant low levels of DNA-XL were found, which had disappeared after 48 h. In accordance with this observation, serum transaminase levels were only slightly elevated.

Animals↗
PubMed1978

Cytospectrophotometric study of the kinetics of histochemical reaction of GABA-transaminase in cryostat sections of rat cerebellar cortex.

A modification of the histochemical method for demonstration of GABA-transaminase is proposed. Substrate and cofactor concentrations are chosen on the basis of kinetic investigation in cryostat sections of the rat cerebellar cortex. Enzymatic reactions were measured by quantitative microspectrophotometry. Michaelis constants for alpha-oxoglutarate in the Purkinje cell layer and granular layer (Km 1.7 x 10(-3) M) and white matter (Km 3.8 x 10(-3) M) are found. It is shown that alpha-oxoglutarate in concentrations higher than 5.2 x 10(-3) M (1 mg/ml) suppresses the reaction in sections by competitive inhibition. The advisability of addition of malonate, PMS and cyanide to the incubation medium is confirmed. It is suggested that there are some isoenzymes of GABA-transaminase with predominant localization either in neurons or glia.

Animals↗
PubMed1989

Adverse effects of three different forms of heparin therapy: thrombocytopenia, increased transaminases, and hyperkalaemia.

A prospective study has been made of the incidence of changes in transaminase levels, hyperkalaemia and thrombocytopenia in three groups of patients: 89 consecutive patients with venous thrombosis receiving therapeutic heparinization, 49 patients admitted because of hip fracture and receiving prophylactic low-dose conventional heparin, and 43 patients admitted because of hip fracture and randomly allocated to receive low molecular weight heparin. Laboratory measurements were made on admission and 8 days after commencing heparin. Only two patients on high-dose heparin developed thrombocytopenia. Increased transaminases were frequent with conventional heparin (18% and 32% of patients on high-dose heparin developed abnormal AsT and AlT values, respectively compared with 14% and 17% patients on low dose therapy). In contrast, only one patient on low molecular weight heparin developed abnormal AlT activity. Hyperkalaemia was uncommon in patients on any form of heparin therapy, and severe hyperkalaemia occurred in only one patient.

Adult↗
PubMed1999

Cloning, characterisation and regulation of the ornithine transaminase (otaA) gene of Aspergillus nidulans.

The ornithine transaminase (otaA) gene of Aspergillus nidulans has been cloned by transformation of the A. nidulans pro-ota- mutant strain with a cosmid gene library. The otaA gene contains two introns and potentially codes for a 453-aa-long protein. The deduced amino-acid sequence is homologous to known ornithine transaminases from Saccharomyces cerevisiae, Plasmodium falciparum, Vigna aconitifolia, rat, mouse and man, particularly in the pyridoxal phosphate-binding domain. The expression of the otaA gene is specifically induced by arginine, and is also under the control of nitrogen-metabolite and carbon-catabolite repression. Regulation of the gene occurs at both transcriptional and post-transcriptional levels. The promoter region of otaA contains putative AREA and CREA binding-sites. Fusion proteins containing AREA or CREA DNA-binding domains bind some of these sites. CREA binding-sites correspond very well to the CREA-binding consensus sequence which is SYGGRG. AREA binding-sites are composed of GATT sequences which are not typical binding sites for the GATA - binding family of transcription factors.

Amino Acid Sequence↗
PubMed2006

Isolated elevated serum transaminases leading to the diagnosis of asymptomatic Pompe disease.

An asymptomatic boy, aged 1.5 years, was referred with presumed liver disease because of persistently increased transaminase. Ultimately Pompe disease was confirmed, without specific abnormalities in muscle biopsy. This case demonstrates that increased transaminases do not always suggest liver disease. It is hard to determine prognosis and to decide whether enzyme replacement therapy should be started in asymptomatic patients with Pompe disease.

Alanine Transaminase↗
PubMed2002

Possible mechanisms of elevation of serum transaminase levels during interferon-beta therapy in chronic hepatitis C patients.

BACKGROUND: Serum transaminase levels are frequently elevated in patients with chronic hepatitis C who are receiving interferon (IFN)-beta therapy, despite hepatitis C virus (HCV)-RNA being eradicated from the serum. We examined liver histology to determine the reason for this elevation. METHODS: Patients with chronic hepatitis C, diagnosed by liver histology and positive serum HCV-RNA, were given intravenous injections of IFN-beta, at a daily dose of 6 MU, every day for periods of 6 to 12 weeks. When serum alanine transaminase (ALT) levels during the therapy were higher than three times the levels before the therapy, liver biopsy was performed. Histological findings on light microscopy were compared in liver biopsy specimens obtained before and during the therapy. RESULTS: An increase in serum ALT levels was found in 19 of the 102 patients who received the IFN-beta therapy. Autoimmune hepatitis was not contributory in any of these 19 patients, because serum antinuclear antigen was negative and IgG levels were not increased. Liver histology was examined in 10 of these 19 patients. The period between the start of IFN-beta therapy and the biopsy during the therapy ranged from 14 to 46 days. In 2 patients, the extent of mononuclear cell infiltration in the liver and hepatocyte necrosis was less than the extent before the therapy. In the remaining 8 patients, the grade of chronic hepatitis was unchanged during,the therapy, but vacuole formation and apoptotic nuclei in hepatocytes were found in 2 patients, and centrilobular necrotic areas in 1 patient. CONCLUSIONS: The elevation of serum ALT levels during IFN-beta therapy in chronic hepatitis C patients was not a result of increased hepatitis activity. Degenerative, apoptotic, and necrotic changes in hepatocytes, probably a result of the cytotoxic effects of IFN-beta, may have contributed to this elevation of ALT levels. However, such changes were absent in most of the patients, suggesting that decisions on the discontinuation of IFN-beta therapy must be made in accordance with liver histology findings.

Adult↗
PubMed1986

Elevated serum transaminase levels during ritodrine administration.

Two cases are presented of the occurrence of elevated serum transaminase levels during ritodrine administration for the treatment of premature labor. The clinical course of these cases suggests that elevated transaminase levels per se do not require the discontinuation of beta-sympathomimetic tocolytic treatment.

Adult↗
PubMed1986

Affinity purification and properties of rat liver mitochondrial L-alanine:4,5-dioxovalerate transaminase and its inhibition by hemin.

The present study describes a new rapid procedure for purification of L-alanine:4,5-dioxovalerate transaminase from rat liver mitochondria which was purified 243-fold with a 32% yield to apparent homogeneity. The purification procedure involved protamine sulfate treatment, followed by phenyl-Sepharose CL-4B column chromatography and alanine-Sepharose 4B affinity chromatography. The Km values for L-alanine and 4,5-dioxovalerate were 3.3 and 0.28 mM, respectively. The enzyme-bound pyridoxal phosphate content was estimated to be two molecules per enzyme molecule. The purified enzyme was inhibited by the reaction product pyruvic acid, substrate analog, methylglyoxal, and sulfhydryl inhibitors. Excess concentrations of 4,5-dioxovalerate was also found to inhibit the enzyme and our experiments failed to demonstrate reversibility of the reaction. Only hemin among the intermediate compounds of heme metabolism tested was shown to be an inhibitor of purified alanine:4,5-dioxovalerate transaminase. Hemin was further shown as an uncompetitive inhibitor of both alanine and dioxovalerate.

Animals↗
PubMed1990

Characteristics of L-alanine:4,5-dioxovaleric acid transaminase: an alternate pathway of heme biosynthesis in yeast.

The present study reports for the first time the presence of the enzyme L-alanine:4,5-dioxovaleric acid transaminase (EC 2.6.1.43), which catalyzes the irreversible synthesis of 5-aminolevulinic acid in three strains of yeast: Candida albicans 3100, Saccharomyces cerevisiae 3059, and S. cerevisiae S288C. The enzyme was predominantly present in the cytosol and was purified from C. albicans 3100 by about 200-fold with an overall yield of 23% to apparent homogeneity. The purification procedure involved heat treatment, followed by affinity chromatography on L-alanine-Sepharose CL-4B, ion-exchange chromatography on DEAE-cellulose DE-52, and chromatography on hydroxyapatite. As judged by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme appeared to be a monomeric protein of relative molecular mass 59,000. The enzyme activity was stimulated by pyridoxal phosphate and was optimally active at 60 degrees C. The purified enzyme had an isoelectric point of 4.7 and a pH optimum of 7.2 Km values of the enzyme for L-alanine, pyridoxal phosphate, and 4,5-dioxovaleric acid were 2.8 X 10(-7), 5.0 X 10(-7), and 1.05 X 10(-5) M, respectively. The Vmax of the enzymatic reaction was 5 X 10(-6) mol/mg/h. Antibody raised against the purified yeast L-alanine:4,5-dioxovaleric acid transaminase did not cross-react with the same enzyme from rat liver and kidney.

Candida albicans↗
PubMed1975

Further characterization of L-leucine-pyruvate transaminase from Acetobacter suboxydans.

L-Leucine-pyruvate transaminase obtained from Acetobacter suboxydans exhibited absorbance maxima to 280 and 332 nm. The 332 nm peak was derived from the coenzyme bound to the enzyme protein with the epsilon NH2 of a lysine residue. The transaminase showed reactivity against many L-amino acids. The relation between the reactivity and the structure of the amino donor is discussed. The Michaelis constants for L-leucine, pyruvate, L-alanine and alpha-ketoisocaproate were 6.7, 3.1, 7.1 and 0.9 mM, respectively. The equilibrium constant was 5.3. The activation energy at pH 5.0 was 8,800 cal/mol.

Acetobacter↗
PubMed1980

Purification, properties and formation of arginine-alpha-ketoglutarate transaminase in Arthrobacter simplex.

Arginine-alpha-ketoglutarate transaminase was purified 460-fold with 1.4% yield from Arthrobacter simplex grown on arginine as a carbon source. The preparation was more than 90% pure on polyacrylamide gel electrophoresis, and the molecular weight of the enzyme was calculated to be 110 000. The enzyme exhibited absorption maxima at 280, 330 and 370 nm. The 370 nm peak decreased with increase in the 330 nm peak on addition of arginine Km values for arginine, alpha-ketoglutarate, glutamate and alpha-keto-delta-guanidinovalerate were 2.9, 8.1, 25 and 0.30 mM, respectively. Those for pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate were 0.25 and 0.57 microM. The enzyme reacted optimally at pH 8.0--8.5. The synthesis of arginine-alpha-ketoglutarate transaminase was inducible by arginine and alpha-keto-delta-guanidinovalerate.

Arthrobacter↗
PubMed1994

Molecular cloning of rat kynurenine aminotransferase: identity with glutamine transaminase K.

The enzyme kynurenine aminotransferase (KAT) catalyses the conversion of L-kynurenine to kynurenic acid. A combination of polymerase chain reaction techniques and hybridization screening was used to isolate a cDNA clone encompassing the entire coding region of KAT from rat kidney. Identification of the cDNA as coding for KAT was based both on the comparison of amino acid sequences obtained from purified rat KAT and on the expression of KAT activity in COS-1 cells transfected with the cDNA. RNA blot analysis indicated that KAT mRNA is widely expressed in rat tissues. Cultured cells transfected with the cDNA for KAT also showed glutamine transaminase K activity. Based mainly on sequence data, these results demonstrate that rat kidney KAT is identical with glutamine transaminase K.

Amino Acid Sequence↗
PubMed1983

Estradiol-induced hepatic protein synthesis and transaminase activity in the male flounder, Platichthys flesus (L.).

A continued accumulation of vitellogenin was observed in the serum through 28 days after administration of spaced large doses of estradiol. The level of estradiol in the serum reached a maximum on Day 4, followed by a continued decrease until a basal concentration was reached at Day 15. The estradiol treatment increased the in vitro hepatic protein synthesis activity, measured as polyphenylalanine synthesis per unit cytoplasmic RNA, within 2-4 days reaching a maximum after 7 days. The effect was transitory and reduced to less than 50% within 15 days. After restimulation a second rise in protein synthesis activity was observed. The cellular content of bulk RNA i the liver showed a slow but steady accumulation through the 28 days. The specific activity of glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase in the liver decreased 35 and 20% relative to control, respectively, within 7 days after the first stimulation and again 14 days after restimulation. The concentration of serum protein showed a steady increase throughout the experimental period. The concentration of serum ninhydrine positive substances was lowered to 50% relative to the controls within the first 7 days after start of treatment with hormone.

Alanine Transaminase↗