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1.
Abstract The specific activity of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase changed when Penicillium chrysogenum was grown on different carbon sources. In the presence of 2% lactose, the activities of these enzymes were approximately 25–35% lower than those in media containing 2% glucose or 2% fructose. We assume that an increase in cAMP concentration was responsible for the observed decreases in the enzyme activities, because a higher cAMP concentration could be detected when the mycelium was grown in a medium containing solely lactose as carbon source. The likely role played by cAMP in the regulation was also demonstrated by the addition of either cAMP or caffeine to the medium. 相似文献
2.
The activities and kinetics of the enzymes G6PDH (glucose-6-phosphate dehydrogenase) and 6PGDH (6-phosphogluconate dehydrogenase) from the mesophilic cyanobacterium Synechococcus 6307 and the thermophilic cyanobacterium Synechococcus 6716 are studied in relation to temperature. In Synechococcus 6307 the apparent K
m's are for G6PDH: 80M (substrate) and 20M (NADP+); for 6PGDH: 90M (substrate) and 25M (NADP+). In Synechococcus 6716 the apparent K
m's are for G6PDH: 550M (substrate) and 30M (NADP+); for 6PGDH: 40M (substrate) and 10M (NADP+). None of the K
m's is influenced by the growth temperature and only the K
m's of G6PDH for G6P are influenced by the assay temperature in both organisms. The idea that, in general, thermophilic enzymes possess a lower affinity for their substrates and co-enzymes than mesophilic enzymes is challenged.Although ATP, ribulose-1,5-bisphosphate, NADPH and pH can all influence the activities of G6PDH and 6PGDH to a certain extent (without any difference between the mesophilic and the thermophilic strain), they cannot be responsible for the total deactivation of the enzyme activities observed in the light, thus blocking the pentose phosphate pathway.Abbreviations G6PDH
glucose-6-phosphate, dehydrogenase
- 6PGDH
6-phosphogluconate dehydrogenase
- G6P
glucose-6-phosphate
- 6PG
6-phosphogluconate
- RUDP
ribulose-1,5-bisphosphate
- Tricine
N-Tris (hydroxymethyl)-methylglycine 相似文献
3.
We studied the maternal effect for two enzymes of the pentose cycle, 6-phosphogluconate dehydrogenase (6PGD) and glucose-6-phosphate dehydrogenase (G6PD), using a genetic system based on the interaction of Pgd? and Zw? alleles, which inactivate 6PGD and G6PD, respectively. The presence and formation of the enzymes was investigated in those individuals that had not received the corresponding genes from the mother. We revealed maternal forms of the enzymes, detectable up to the pupal stage. The activities of “maternal” 6PGD and G6PD per individual increased 20-fold to 30-fold from the egg stage to the 3rd larval instar even in the absence of normal Pgd and Zw genes. Immunologic studies have shown that the increase in 6PGD activity is due to an accumulation of the maternal form of the enzyme molecules. We revealed a hybrid isozyme resulting from an aggregation of the subunits of isozymes controlled by the genes of the mother and embryo itself. These results indicate that the maternal effect in the case of 6PGD is due to a long-lived stable mRNA transmitted with the egg cytoplasm and translated during the development of Drosophila melanogaster. 相似文献
4.
Mark Ming-Long Hsu MD Jen-Chyi Chang Koji Yokoyama Kazuko Nishimura Makoto Miyaji 《Mycopathologia》1994,127(2):77-81
Twenty-one strains ofCryptococcus neoformans isolated from patients in Taiwan were characterized for serotypes and mating types. Slide agglutination test was performed with 8 factor-specific sera (Iatron Company, Japan) to determine the serotypes. Wheat bran agar (WBA) and malt extract agar (MEA, Wickerham) media were used for the mating tests. Twenty of the isolates were of serotype A, and one was serotype B. Except for 2 strains of serotype A, all of the serotype A strains mated withFilobasidiella neoformans var.neoformans, mating type a. The only serotype B strain mated withF. neoformans var.bacillispora mating type a in MEA medium. These data revealed the low prevalence (1/21; 4.8%) ofC. neoformans var.gattii in Taiwan, a subtropically located island. 相似文献
5.
The three-dimensional ultrastructure ofCryptococcus neoformans was studied by quick-freezing and deep-etching (QF-DE) method.C. neoformans, strain CDC551, was cultured on agar. The viable yeast cells (107 cells) were inoculated into each mouse from the tail vein. Three weeks after the inoculation, the brains of the mice were perfused with fixatives, quickly frozen, freeze-fractured, deeply etched and rotary shadowed with platinum and carbon. In addition, the viable cells ofC. neoformans on agar were picked up and quickly frozen, and replica membranes were prepared as described above. The ultrastructure ofC. neoformans was three-dimensionally demonstrated by the QF-DE method. The capsule was composed of fine meshworks of microfibrils (10–13 nm in diameter), which were directly attached to the cell walls. The capsule of the in vivo yeasts (yeast cells in the brain lesion) was thicker than that of the in vitro yeasts (yeast cells on agar culture). At the outer part of the cell wall, a particle-accumulating layer was observed. This layer in vivo was thicker than that in vitro. Occasionally, the yeast cells were ingested by phagocytes in the mouse brain. Although the cytoplasm of such yeast cells was destroyed, the capsular meshworks were well preserved. The ultrastructure of the capsule was the same both in cultured and phagocytized yeasts in the cystic lesions of the brains. This lack of morphological changes of the capsular meshworks suggests that they are resistant to the digestion by phagocytes. This stability of capsular structures may provide one of the important pathogenic factors in cystic lesions byC. neoformans. 相似文献
6.
Neus Madrenys Charles De Vroey Chris Raes-Wuytack Dr Josep M. Torres-Rodríguez 《Mycopathologia》1993,122(2):65-68
Filobasidiella neoformans is the teleomorphic state ofCryptococcus neoformans and it is a heterothalic. The purpose of this study was to establish the proportions of each mating types (a, ) from among 195 strains ofC. neoformans isolated from clinical material. The culture medium used was sunflower agar. Cultures were incubated at 20–22 °C for 15 days and observed periodically for one month. Non-reactive strains were mated several times with different reactive strains. Under these conditions 96.8% of the strains were found to be reactors. Among both varieties ofC. neoformans, mating type was found to have the highest frequency of 95% in the varietyneoformans and 84% in the varietygattii. These results showed a higher reactivity in comparison with other investigators. This difference could be due to the medium used or to repeated mating with different reactive tested strains. 相似文献
7.
Three independent genes are responsible for 6-phosphogluconate dehydrogenase (6PGDH) activity in tomato. 6Pgdh-2, located on chromosome 12, codes for subunits of an active dimer which is restricted to the plastids. 6Pgdh-1, chromosome 4, and 6Pgdh-3, chromosome 5, code for subunits which form three dimers—two homodimers and an intergenic heterodimer. The latter three isozymes are found in the cytosol. 6Pgdh-1, 6Pgdh-2, and 6Pgdh-3 code for subunits with estimated molecular weights of 49,500, 50,500, and 51,200, respectively. The intergenic heterodimer encoded by 6Pgdh-1 and 6Pgdh-3 is thus composed of subunits that differ in length by approximately 15 amino acid residues. Divergence in the length and primary subunit structure may account for the lower thermal stability of the intergenic heterodimer compared with the corresponding homodimers. A limited survey of other solanaceous plant species suggests that the duplication of cytosolic 6PGDH-coding genes found in tomato may be widespread in the family.This is journal article 1145, Agricultural Experiment Station, New Mexico State University. This research was supported by USDA Grant 82-CRCR-1-1014 to S. D. Tanksley. We acknowledge the technical support of Jaime Iglesias and Fernando Loiaza. 相似文献
8.
Cells of five strains ofCryptococcus neoformans were obtained for partial analysis of lipid composition. Quantitative analysis of lipids and sterols were completed, as well as qualitative analysis of sterols by thin-layer chromatography and by the ultraviolet spectra. Such determinations were made on cells cultured in the absence and presence of amphotericin B at sub-MIC (minimal inhibitory concentration) levels. Marked alterations of the lipid and sterol contents were observed in the amphotericin B — treated cells. Moreover, ergosterol disappeared in these antibiotic-exposed cells. It is concluded that amphotericin B altered the lipid profiles, especially sterols ofC. neoformans. 相似文献
9.
Starch gel electrophoresis of erythrocytes from 1812 Macaca mulatta has unequivocally demonstrated that the 6-phosphogluconate dehydrogenase (6PGD) isozymes are controlled by two autosomal codominant alleles. Limited data on erythrocytes from 89 Macaca speciosa were also consistent with autosomal codominance.This work was supported in part by NIH Grants HD 07835 (WHS) and RR-00167 (Wisconsin Regional Primate Research Center) and by the Research Committee of the UW Graduate School (Project No. 170207).Paper No. 2146 of the Laboratory of Genetics, and Publication No. 16-045 of The Wisconsin Regional Primate Research Center. 相似文献
10.
Developmental profiles of the second- and third-chromosome modifiers of the activities of glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) in Drosophila melanogaster were investigated. Third-chromosome modifiers showed very strong effects on both enzyme activities at larval, pupal, and adult stages, whereas second-chromosome effects were detected mainly at larval and adult stages. For both enzyme activities and both chromosomes, the correlation over line means between larval and pupal stages was significantly positive, but the correlation between larval or pupal stage and adult stage was not significant. This result suggests that the actions of modifiers on G6PD and 6PGD activities are influenced by the change of developmental stages. Correlation between G6PD and 6PGD activities was positive and highly significant throughout the developmental stages for both sets of chromosomes, although third-chromosome correlations were slightly higher than second-chromosome correlations. The magnitude of the correlation between G6PD and 6PGD activities does not seem to be influenced by the change of development. Diallel crosses for both sets of chromosomes indicate that the action of activity modifiers is mainly additive for both sets of chromosomes, but dominance effects were detected in some cases in adult males. Significant maternal effects were detected for the third chromosome for both enzyme activities until the pupal stage. The change of the activity modifier action after emergence of the imago and the significant correlation between G6PD and 6PGD activities were also detected for diallel progeny.This work was supported by Public Health Service Grant NIH-GM11546.Paper No. 10211 of the journal series of the North Carolina Agricultural Research Service, Raleigh, North Carolina 27695. 相似文献
11.
Jan J. laski Guichang Zhang Urmila Basu Julie L. Stephens Gregory J. Taylor 《Physiologia plantarum》1996,98(2):477-484
We have investigated the effect of aluminum (Al) on the activity of glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGDH; EC 1.1.1.44) isolated from 5-mm root apices of 4-day-old wheat ( Triticum aestivum ) cultivars differing in resistance to Al. Rapid increases in G6PDH and 6PGDH activities were observed in Al-resistant cultivars (PT741 and Atlas 66) during the first 10 h of treatment with 100 μ M Al, while no change in the activity of either enzyme was observed in Al-sensitive cultivars (Katepwa and Neepawa) during a 24-h exposure to Al. The Al-induced increases in enzyme activities observed in the Al-resistant PT741 appear to reflect an induction of protein synthesis since the increases were completely abolished by 1 m M cycloheximide. No differences in G6PDH and 6PGDH activities were observed between the Al-sensitive and the Al-resistant genotypes when Al was supplied in vitro. Under these conditions, an increase in Al concentration from 0 to 1.4 m M caused a gradual decrease in activity of both enzymes, irrespective of the Al-resistance of whole seedlings. Aluminum-sensitive and aluminum-resistant cultivars also differed in the rate and extent of accumulation of slowly-exchanging Al in 5-mm root apices. During the first 6 h of Al treatment, Al accumulation was only 10% more rapid in Katepwa than in PT741. After 24-h exposure, accumulation in the Al-sensitive Katepwa, was two-fold higher. A decline in Al accumulation in a slowly-exchanging compartment as well as a decrease in activities of G6PDH and 6PGDH were found in the Al-resistant PT741, when seedlings were transferred to Al-free treatment solutions after 16-h exposure to 100 μ M Al. These results suggest that rapid induction of G6PDH and 6PGDH in the Al-resistant line PT741 by Al may play a role in the mechanism of Al resistance, possibly by regulation of the pentose phosphate pathway. 相似文献
12.
Berivan Tandogan Nuray N. Ulusu 《Journal of enzyme inhibition and medicinal chemistry》2013,28(2):225-230
Glucose-6-phosphate dehydrogenase (G-6-PD) is the first enzyme in the pentose phosphate pathway. Cadmium is a toxic heavy metal that inhibits several enzymes. Zinc is an essential metal but overdoses of zinc have toxic effects on enzyme activities. In this study G-6-PD from lamb kidney cortex was competitively inhibited by zinc both with respect to glucose-6-phosphate (G-6-P) and NADP+ with Ki values of 1.066 ± 0.106 and 0.111 ± 0.007 mM respectively whereas cadmium was a non-competitive inhibitor with respect to both G-6-P and NADP+ Ki values of 2.028 ± 0.175 and 2.044 ± 0.289 mM respectively. 相似文献
13.
Jan J. laski Guichang Zhang Urmila Basu Julie L. Stephens Gregory J. Taylor 《Physiologia plantarum》1996,98(3):477-484
We have investigated the effect of aluminum (Al) on the activity of glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGDH; EC 1.1.1.44) isolated from 5-mm root apices of 4-day-old wheat ( Triticum aestivum ) cultivars differing in resistance to Al. Rapid increases in G6PDH and 6PGDH activities were observed in Al-resistant cultivars (PT741 and Atlas 66) during the first 10 h of treatment with 100 μ M Al, while no change in the activity of either enzyme was observed in Al-sensitive cultivars (Katepwa and Neepawa) during a 24-h exposure to Al. The Al-induced increases in enzyme activities observed in the Al-resistant PT741 appear to reflect an induction of protein synthesis since the increases were completely abolished by 1 m M cycloheximide. No differences in G6PDH and 6PGDH activities were observed between the Al-sensitive and the Al-resistant genotypes when Al was supplied in vitro. Under these conditions, an increase in Al concentration from 0 to 1.4 m M caused a gradual decrease in activity of both enzymes, irrespective of the Al-resistance of whole seedlings. Aluminum-sensitive and aluminum-resistant cultivars also differed in the rate and extent of accumulation of slowly-exchanging Al in 5-mm root apices. During the first 6 h of Al treatment, Al accumulation was only 10% more rapid in Katepwa than in PT741. After 24-h exposure, accumulation in the Al-sensitive Katepwa, was two-fold higher. A decline in Al accumulation in a slowly-exchanging compartment as well as a decrease in activities of G6PDH and 6PGDH were found in the Al-resistant PT741, when seedlings were transferred to Al-free treatment solutions after 16-h exposure to 100 μ M Al. These results suggest that rapid induction of G6PDH and 6PGDH in the Al-resistant line PT741 by Al may play a role in the mechanism of Al resistance, possibly by regulation of the pentose phosphate pathway. 相似文献
14.
Jasbir Singh Nordlie Robert C. Roger A. Jorgenson 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,678(3):477-482
Vanadate has been found to be a potent inhibitor of both the hydrolytic and synthetic activities of the multi- functional enzyme glucose-6-phosphatase (d-glucose-6-phosphatase phosphohydrolase, EC 3.1.3.9). The enzyme, when studied in both microsomal preparations and in situ using permeable isolated hepatocytes, is inhibited by micromolar concentrations of vanadate. The inhibition by vanadate is greater in detergent-treated than in untreated microsomes. In both the microsomal preparations and permeable hepatocytes, the inhibition by vanadate is competitive with the phosphate substrate and is greater for the phosphotransferase than the hydrolase activity of the enzyme. The KI values of vanadate for carbamyl-phosphate : glucose phosphotransferase and glucose-6-phosphate phosphohydrolase determined with permeable hepatocytes are in good agreement with the values determined with detergent-dispersed microsomes. The previously described inhibition of glucose-6-phosphate phosphohydrolase by ATP (Nordlie, R.C., Hanson, T.L., Johns, P.T. and Lygre, D.G. (1968) Proc. Natl. Acad. Sci. USA 60, 590–597) can now be explained by the vanadium contamination of the commercially available ATP samples used. In contrast with glucose-6-phosphatase, hepatic glucokinase and hexokinase were not inhibited by vanadate. Physiological implications and utilitarian experimental applicability of vanadate as a selective metabolic probe, based on these observations, are suggested. 相似文献
15.
Inhibitory effects of some drugs were investigated on human erythrocyte 6-phosphogluconate dehydrogenase obtained with a 6552-fold purification in a yield of 78% using 2′, 5′-ADP Separose 4B affinity gel. Which on SDS polyacrylamide gel electrophoresis showed a single band. Larnoxicam, metronidazole, imipenem, ornidazole, vancomycin, clindamycin, and amoxicillin exhibited inhibitory effects on the enzyme in vitro with IC50 values of 0.17, 0.23, 0.43, 21.79, 46.39, 117.43 and 287.35 mM, and the Ki constants 0.40 ± 0.04, 0.57 ± 0.06, 0.77 ± 0.11, 42.40 ± 2.89, 65.60 ± 4.03, 130.22 ± 9.21, and 287.58 ± 10.56 mM, respectively. While vancomycin, clindamycin and amoxicillin showed competitive inhibition the other drugs displayed noncompetitive inhibition. 相似文献
16.
JosM. Bautista Amando Garrido-Pertierra Germn Soler 《Biochimica et Biophysica Acta (BBA)/General Subjects》1988,967(3)
The kinetic mechanism of the reaction catalyzed by glucose-6-phosphate dehydrogenase (EC 1.1.1.49) from Dicentrarchus labrax liver was examined using initial velocity studies,NADPH and glucosamine 6-phosphate inhibition and alternate coenzyme experiments. The results are consistent with a steady-state ordered sequential mechanism in which NADP+ binds first to the enzyme and NADPH is released last. Replots of NADPH inhibition show an uncommon parabolic pattern for this enzyme that has not been previously described. A kinetic model is proposed in agreement with our kinetic results and with previously published structural studies (Bautista et al. (1988) Biochem. Soc. Trans. 16, 903–904). The kinetic mechanism presented provides a possible explanation for the regulation of the enzyme by the [NADPH]/[NADP+] ratio. 相似文献
17.
Cristina Elena Canteros Laura Rodero Maria Cristina Rivas Graciela Davel 《Mycopathologia》1996,136(1):21-23
A rapid method to evidence urease activity is described. Urea hydrolysis and consequent production ammonia are detected by a chemical reaction producing a blue phenol compound (indophenol blue). Three hundred and three yeast were tested. Out of 107 urease-positive organisms detected by Christensen's Urea Agar Test (CUAT) 102 were positive by our method. No false negatives were observed by this method when testing 87 Cryptococcus strains. Ths practical screening test for presumptive identification of Cryptococcus neoformans is simple, unaffected by pH changes and requires 15 minutes to be performed. 相似文献
18.
G6PD, 6PGD and GR have been purified separately in the single step from rat lung using 2′, 5′-ADP Sepharose 4B affinity chromatography. The purified enzymes showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weights of the enzymes were estimated to be 134?kDa for G6PD, 107?kDa for 6PGD and 121?kDa for GR by Sephadex G-150 gel filtration chromatography, and the subunit molecular weights was respectively found to be 66, 52 and 63?kDa by SDS-PAGE. Optimum pH, stable pH, optimum ionic strength, optimum temperature, KM and Vmax values for substrates were determined. Product inhibition studies were also performed. The enzymes were inhibited by levofloxacin, furosemide, ceftazidime, cefuroxime and gentamicin as in vitro with IC50 values in the range of 0.07–30.13?mM. In vivo studies demonstrated that lung GR was inhibited by furosemide and lung 6PGD was inhibited by levofloxacin. 相似文献
19.
Summary Previous studies examining the regulation of the synthesis of G6PDH and 6PGDH in rat liver and adipose tissue have focused on the induction of these enzymes by different diets and some hormones. In rat liver these enzymatic activities seem to be regulated by a mechanism involving changes in the NADPH requirements. In this paper we have studied the effect of changes in the flux through different NADPH-consuming pathways on G6PDH and 6PGDH levels in adipose tissue and on the NADPH/NADP ratio. The results show that: I) an increase in the consumption of NADPH, caused by the activation of either fatty acid synthesis or detoxification systems which consume NADPH, is paralleled by an increase in the levels of these enzymes; II) when the increase in consumption of NADPH is prevented, the G6PDH and 6PGDH levels do not change.Abbreviations G6PDH
Glucose-6-Phosphate Dehydrogenase
- 6PGDH
6-Phosphogluconate Dehydrogenase
- GR
Glutathione Reductase
- ME
Malic Enzyme
- tBHP
t-Butyl Hydroperoxide
- NF
Nitrofurantoin
- CumOOH
Cumene Hydroperoxide 相似文献
20.
Antonio Ayala Isabel Fabregat Alberto Machado 《Molecular and cellular biochemistry》1990,95(2):107-115
Summary Previous studies examining regulation of synthesis of Glucose-6-Phosphate and 6-Phosphogluconate dehydrogenase in rat liver have focussed on the induction of these enzymes by different diets and some hormones. However, the precise mechanism regulating increases in the activities of these enzymes is unknown and the factors involved remain unidentified. Considering that many of these metabolic conditions occur simultaneously with the increase of some NADPH consuming pathway, in particular fatty acid synthesis, we suggest that the activities of Glucose-6-Phosphate and 6-Phosphogluconate dehydrogenase could be regulated through a mechanism involving changes in the NADPH requirement. Here, we have studied the effect of changes in the flux through different NADPH consuming pathways on the NADPH/NADP ratio and on Glucose-6-Phosphate and 6-Phosphogluconate levels. The results show that: i) an increase in consumption of NADPH, caused by activation of fatty acid synthesis or the detoxification system which consumes NADPH, is paralleled by an increase in levels of these enzymes; ii) when increase in consumption of NADPH is prevented, Glucose-6-Phosphate and 6-Phosphogluconate dehydrogenase levels do not change.Abbreviations G6PDH
Glucose-6-Phosphate Dehydrogenase
- 6PGDH
6-Phosphogluconate Dehydrogenase
- ME
Malic Enzyme
- NF
Nitrofurantoin
- CumOOH
Cumene Hydroperoxide
- t-BHP
t-Butyl hydroperoxide
- BCNU
1,3,-Bis (2-chloroethyl)-1-nitrosourea
- GR
Glutathione Dehydrogenase
- 2-ME
2-Mercaptoethanol
- DTT
Dithiothreitol
- NADP
B-Nicotinamide-Adenine Dinucleotide Phosphate
- NADPH
B-Nicotinamide-Adenine Dinucleotide Phosphate Reduced
- EDTA
Ethylenediaminetetraacetic Acid
- GSH
Glutathione Reduced Form
- GSSG
Glutathione Oxidized Form 相似文献