Regulatory effects of purine nucleotide analogs with liver glutamate dehydrogenase

Lascu, Ioan; Bârzu, Tereza; Ty, N.G.; Ngoc, L.D.; Bârzu, Octavian; Mantsch, Henry H.

doi:10.1016/0005-2744(77)90239-x

Cited by 10 publications

(11 citation statements)

References 13 publications

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“…Furthermore, when ATP and GTP were tested as effectors, they inhibited GDH activity (Table III). Vertebrates possess a GDH that is subject to allosteric inhibition by GTP (57). Study of the influence of other molecules on the GDH activity revealed that some intermediates of the Krebs cycle (isocitrate, succinate, fumarate, malate, and oxalacetate) as well as glyoxylic acid and glutaric acid are also inhibitors (see Table III).…”

Section: Resultsmentioning

confidence: 99%

A New Class of Glutamate Dehydrogenases (GDH)

Miñambres

Olivera

Jensen³

et al. 2000

Journal of Biological Chemistry

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A new class of glutamate dehydrogenase (GDH) is reported. The GDH of Streptomyces clavuligerus was purified to homogeneity and characterized. It has a native molecular mass of 1,100 kDa and exists as an ␣ 6 oligomeric structure composed of 183-kDa subunits. GDH, which requires AMP as an essential activator, shows a maximal rate of catalysis in 100 mM phosphate buffer, pH 7.0, at 30°C. Under these conditions, GDH displayed hyperbolic behavior toward ammonia (K m , 33 mM) and sigmoidal responses to changes in ␣-ketoglutarate (S 0.5 1.3 mM; n H 1.50) and NADH (S 0.5 20 M; n H 1.52) concentrations. Aspartate and asparagine were found to be allosteric activators. This enzyme is inhibited by an excess of NADH or NH 4 ؉ , by some tricarboxylic acid cycle intermediates and by ATP. This GDH seems to be a catabolic enzyme as indicated by the following: (i) it is NAD-specific; (ii) it shows a high value of K m for ammonia; and (iii) when S. clavuligerus was cultured in minimal medium containing glutamate as the sole source of carbon and nitrogen, a 5-fold increase in specific activity of GDH was detected compared with cultures provided with glycerol and ammonia. GDH has 1,651 amino acids, and it is encoded by a DNA fragment of 4,953 base pairs (gdh gene). It shows strong sequence similarity to proteins encoded by unidentified open reading frames present in the genomes of species belonging to the genera Mycobacterium, Rickettsia, Pseudomonas, Vibrio, Shewanella, and Caulobacter, suggesting that it has a broad distribution. The GDH of S. clavuligerus is the first member of a class of GDHs included in a subfamily of GDHs (large GDHs) whose catalytic requirements and evolutionary implications are described and discussed.

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Section: Resultsmentioning

confidence: 99%

A New Class of Glutamate Dehydrogenases (GDH)

Miñambres

Olivera

Jensen³

et al. 2000

Journal of Biological Chemistry

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“…Hill coefficients (n H ) in the same experiments were 1.3 and 1.5 for the Gdh1p and Gdh3p enzyme, respectively. In this regard, hexameric glutamate dehydrogenases from other organisms are known to be allosteric enzymes activated by different molecules (AMP, ADP, GTP, ATP, NADP ϩ , succinate, aspartate, and asparagine) (33,(37)(38)(39). The effect of these compounds was assayed for the yeast NADP-GDH isoenzymes, but none of them behaved as an allosteric effector (data not shown).…”

Section: Nadp-gdh Purification From Mutant and Wild-typementioning

confidence: 98%

NADP-Glutamate Dehydrogenase Isoenzymes of Saccharomyces cerevisiae

DeLuna¹,

Avendaño

Riego

et al. 2001

Journal of Biological Chemistry

140

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In the yeast Saccharomyces cerevisiae, two NADP؉ -dependent glutamate dehydrogenases (NADP-GDHs) encoded by GDH1 and GDH3 catalyze the synthesis of glutamate from ammonium and ␣-ketoglutarate. The GDH2-encoded NAD ؉ -dependent glutamate dehydrogenase degrades glutamate producing ammonium and ␣-ketoglutarate. Until very recently, it was considered that only one biosynthetic NADP-GDH was present in S. cerevisiae. This fact hindered understanding the physiological role of each isoenzyme and the mechanisms involved in ␣-ketoglutarate channeling for glutamate biosynthesis. In this study, we purified and characterized the GDH1-and GDH3-encoded NADP-GDHs; they showed different allosteric properties and rates of ␣-ketoglutarate utilization. Analysis of the relative levels of these proteins revealed that the expression of GDH1 and GDH3 is differentially regulated and depends on the nature of the carbon source. Moreover, the physiological study of mutants lacking or overexpressing GDH1 or GDH3 suggested that these genes play nonredundant physiological roles. Our results indicate that the coordinated regulation of GDH1-, GDH3-, and GDH2-encoded enzymes results in glutamate biosynthesis and balanced utilization of ␣-ketoglutarate under fermentative and respiratory conditions. The possible relevance of the duplicated NADP-GDH pathway in the adaptation to facultative metabolism is discussed.

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“…The ion chromatographic separation as well as the purity check of the individual nucleotides was similar to that described in previous publications (Mantsch et al, 1975;Bárzu et al, 1976aBárzu et al, , 1977Lascu et al, 1977). Biochemical Assays.…”

Section: Methodsmentioning

confidence: 95%

“…The 8-bromoadenine nucleotides 8-BrAMP, 8-BrADP, and 8-BrATP were obtained through bromination of the corresponding adenine nucleotides in aqueous solution (Ikehara et al, 1972). The 8-bromoinosine analogues 8-BrIMP, 8-BrIDP, and 8-BrITP were prepared from the corresponding 8-bromoadenine nucleotides by gentle oxidative deamination (Lascu et al, 1977). The 1 .A^-etheno analogues cADP and cATP were synthesized according to the method of Secrist et al (1972) and were a gift of Professor Klingenberg, Munich, Germany.…”

Section: Methodsmentioning

confidence: 99%

“…All 8-substituted ATP analogues were unable to cause actin activation of myosin NTPase, superprecipitation of actomyocin, or myofibrillar contraction. It is interesting, however, that 8-bromoadenine nucleotides can be quite successful in replacing the natural nucleotides with certain enzymatic systems, such as NDP kinase (Nagel et al, 1976;Kezdi et al, 1976), beef liver glutamate dehydrogenase (Koberstein et al, 1976;Lascu et al, 1977), or muscle phosphorylase b (Morange et al, 1976), but are unable to substitute the natural adenine nucleotides as substrates or allosteric effectors with other enzymatic systems, such as rabbit muscle phosphofructokinase (Bárzu et al, 1977), rabbit muscle pyruvate kinase (Koberstein & Sund, 1975;Bárzu et al, 1976a) or leucine-tRNA synthetase from Escherichia coli (Marutzky et al, 1976).…”

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confidence: 99%

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Enzymic properties of 8-bromoadenine nucleotides

Lascu¹,

Kezdi²,

Goia³

et al. 1979

Biochemistry

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8-Bromoadenine nucleotides were tested as potential substrates and/or inhibitors of mitochondrial processes in intact or disrupted organelles, as substrates of various phosphotransferases, and as allosteric effectors in the reactions catalyzed by phosphofructokinase, isocitrate dehydrogenase, glutamate dehydrogenase, and fructose-1,6-bisphosphatase. 8-BrATP and 8-BrADP are not recognized by the translocase system located in the inner mitochondrial membrane and cannot be used as usbstrates in oxidative phosphorylation and related reactions catalyzed be beef heart submitochondrial membranes. This confirms the high specificity for adenine nucleotides of the mammalian systems involved in energy-yielding and energy-requiring reactions. However, 8-BrATP and 8-BrADP are able to substitute for the natural adenine nucleotides in reactions catalyzed by many phosphotransferases, although their capacity as phosphate donors and acceptors is generally much reduced. On the other hand, in almost all investigated cases, the 8-bromoadenine nucleotides have lost the capability of the natural adenine nucleotides to act as allosteric effectors, indicating that the structural requirements for allosteric activity are more stringent than those for catalytic activity.

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Regulatory effects of purine nucleotide analogs with liver glutamate dehydrogenase

Cited by 10 publications

References 13 publications

A New Class of Glutamate Dehydrogenases (GDH)

A New Class of Glutamate Dehydrogenases (GDH)

NADP-Glutamate Dehydrogenase Isoenzymes of Saccharomyces cerevisiae

Enzymic properties of 8-bromoadenine nucleotides

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