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1.
D. R. Joanisse K. B. Storey 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1994,164(3):247-255
The activity of some enzymes of intermediary metabolism, including enzymes of glycolysis, the hexose monophosphate shunt, and polyol cryoprotectant synthesis, were measured in freeze-tolerant Eurosta solidaginis larvae over a winter season and upon entry into pupation. Flexible metabolic rearrangement was observed concurrently with acclimatization and development. Profiles of enzyme activities related to the metabolism of the cryoprotectant glycerol indicated that fall biosynthesis may occur from two possible pathways: 1. glyceraldehyde-phosphate glyceraldehyde glycerol, using glyceraldehyde phosphatase and NADPH-linked polyol dehydrogenase, or 2. dihydroxyacetonephosphate glycerol-3-phosphate glycerol, using glycerol-3-phosphate dehydrogenase and glycerol-3-phosphatase. Clearance of glycerol in the spring appeared to occur by a novel route through the action of polyol dehydrogenase and glyceraldehyde kinase. Profiles of enzyme activities associated with sorbitol metabolism suggested that this polyol cryoprotectant was synthesized from glucose-6-phosphate through the action of glucose-6-phosphatase and NADPH-linked polyol dehydrogenase. Removal of sorbitol in the spring appeared to occur through the action of sorbitol dehydrogenase and hexokinase. Glycogen phosphorylase activation ensured the required flow of carbon into the synthesis of both glycerol and sorbitol. Little change was seen in the activity of glycolytic or hexose monophosphate shunt enzymes over the winter. Increased activity of the -glycerophosphate shuttle in the spring, indicated by greatly increased glycerol-3-phosphate dehydrogenase activity, may be key to removal and oxidation of reducing equivalents generated from polyol cryoprotectan catabolism.Abbreviations 6PGDH
6-Phosphogluconate dehydrogenase
- DHAP
dihydroxy acetone phosphate
- F6P
fructose-6-phosphate
- F6Pase
fructose-6-phospha-tase
- FBPase
fructose-bisphosphatase
- G3P
glycerol-3-phosphate
- G3Pase
glycerol-3-phosphate phophatase
- G3PDH
glycerol-3-phosphate dehydrogenase
- G6P
glucose-6-phosphate
- G6Pase
glucose-6-phosphatase
- G6PDH
glucose-6-phosphate dehydrogenase
- GAK
glyceraldehyde kinase
- GAP
glyceraldehyde-3-phosphate
- GAPase
glyceraldehyde-3-phosphatase
- GAPDH
glyceraldehyde-3-phosphate dehydrogenase
- GDH
glycerol dehydrogenase
- GPase
glycogen phosphorylase
- HMS
hexose monophosphate shunt
- LDH
lactate dehydrogenase
- NADP-IDH
NADP+-dependent isocitrate dehydrogenase
- PDHald
polyol dehydrogenase, glyceraldehyde activity
- PDHgluc
polyol dehydrogenase, glucose activity
- PFK
phosphofructokinase
- PGI
phosphoglucoisomerase
- PGK
phosphoglycerate kinase
- PGM
phosphoglucomutase
- PK
pyruvate kinase
- PMSF
phenylmethylsulfonylfluoride
- SoDH
sorbitol dehydrogenase
-
V
max
maximal enzyme activity
- ww
wet weight 相似文献
2.
Spinach (Spinacia oleracea L.) leaf tissue 70-kilodalton heat-shock cognate was purified by ATP-agarose affinity and gel filtration. Gel filtration of the affinity-purified protein resolved it into three forms: monomer, dimer, and oligomer. In the absence of ATP, the majority of the heat-shock cognate existed as a monomeric form with lesser amounts of dimer and oligomer. Addition of 3 mM ATP to the purified protein, containing all three forms, converted the dimeric and monomeric forms to a high-molecular-weight complex. Removal of ATP from the complex by dialysis resulted in the reappearance of the dimeric and monomeric forms. Addition of ATP to the highly purified monomer had no effect on its gel-filtration migration. Neither purified monomeric or dimeric forms showed stable binding to denatured proteins; however, both forms of the purified heat-shock cognate were able to stabilize the enzymatic activity of bovine adrenal glucose-6-phosphate dehydrogenase over a 48-h period at 25° C. In addition, the activity of glucose-6-phosphate dehydrogenase in the presence of purified heat-shock cognate dimer or monomer could be rapidly decreased in an ATP-dependent fashion depending on the order of the substrate addition to the reaction mixture. Circular-dichroism studies indicated that addition of ATP to the spinach 70-kDa heat-shock cognate caused a conformation change from -helical to a greater -sheet content. How conformational character may influence the stabilizing activity of the heat-shock cognate in a mechanism which does not require stable peptide binding is discussed.Abbreviations BiP
immunoglobulin binding protein
- BSA
bovine serum albumin
- CA
carbonic anhydrase
- CD
circular dichroism
- G6PDH
glucose-6-phosphate dehydrogenase
- HSP
heat shock protein
- HSP70
70-kilodalton heat shock protein
- HSC70
70-kilodalton heat-shock cognate
- MDH
malate dehydrogenase
- PVDF
polyvinylidene difluoride
The authors wish to thank C. Kaye and R. Henry for their critical review and discussion of this paper. The antibody for tobacco BiP was the generous gift of J. Denecke. Financial support for this work was provided by the National Science Foundation DCB 9017625. This is Florida Agricultural Experiment Station Journal Series No. R-04110. 相似文献
3.
Hans-Martin Müller 《Archives of microbiology》1986,144(2):151-157
Batch cultures of Aspergillus niger grown from conidia on a medium with high C/N ratio accumulated gluconate from glucose with a yield of 57%. During almost the whole time of accumulation there was no net synthesis of total protein in the mycelium but the activity per flask and the specific activity of glucose oxidase (EC 1.1.3.4) in mycelial extracts increased whereas both values decreased for glucose dehydrogenase (EC 1.1.99.10) gluconate 6-phosphatase (cf. EC 3.1.3.1, 3.1.3.2), gluconokinase (EC 2.7.1.12), glucose 6-phosphate and phosphogluconate dehydrogenases (EC 1.1.1.49, EC 1.1.1.44), phosphoglucomutase (EC 2.7.5.1), and most enzymes of the Embden-Meyerhof pathway and the tricarboxylic acid cycle. Gluconate dehydratase (EC 4.2.1.39), gluconate dehydrogenase (EC 1.1.99.3) and enzymes of the Entner-Doudoroff pathway could not be detected. By cycloheximide the increase of glucose oxidase activity was inhibited. It is concluded that the high yield of gluconate was due mainly to the net (de novo) synthesis of glucose oxidase which occurred during protein turnover after the exhaustion of the nitrogen source, and which was not accompanied by a net synthesis of the other enzymes investigated. Some gluconate may also have been formed by hydrolytic cleavage of gluconate 6-phosphate.Abbreviations GOD
glucose oxidase
- GD
glucose dehydrogenase
- PP
pentose phosphate
- EM
Embden-Meyerhof
- TCA
tricarboxylic acid 相似文献
4.
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
5.
G. S. Seeto P. C. Veivers K. D. Clements M. Slaytor 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,165(7):571-579
Carbohydrate uptake and catabolism by the gut microbiota of two species of temperate marine herbivorous fish were investigated using enzyme extracts prepared from microbial pellets. The fish studied were the herring cale Odax cyanomelas (Family Odacidae), which feeds on Ecklonia radiata, and the sea carp Crinodus lophodon (Family Aplodactylidae), which feeds primarily on red and green algae. Constitutive phosphoenolpyruvate phosphotransferase systems for glucose, galactose, fructose and mannitol were present in the microbiota of both fish. Hexokinase, fructokinase and mannitol dehydrogenase activities indicated that transport of the corresponding substrates may be coupled to permeases. Galactokinase activity was only detected in C. lophodon, as expected from its diet. Phosphofructokinase and pyruvate kinase activities were taken to indicate that carbohydrate metabolism proceeded via the fructose bisphosphate pathway. Differences in the transport and metabolism of the different monomers by the microbiota of O. cyanomelas and C. lophodon correlated strongly with predicted monomer availability in the gut of each species, suggesting that the microbiota are an integral component of digestion in these fish. The rates of production in adult fish of acetate, the major short-chain fatty acid, were estimated as 136 mol·h-1 in O. cyanomelas and 166 mol·h-1 in C. lophodon. These rates indicate that microbial fermentation is a potentially important source of energy for the host fish.Abbreviations
AK
acetate kinase
-
CTAB
cetyl trimethylammonium bromide
-
FK
fructokinase
- F1P
fructose 1-phosphate
-
F1PK
fructose 1-phosphate kinase
-
F1-6BP
Fructose 1,6-bisphosphate
-
F6P
fructose 6-phosphate
-
GK
galactokinase
-
Gal1P
galactose 1-phosphate
-
G6P
glucose 6-phosphate
-
HK
hexokinase
-
MDH
mannitol dehydrogenase
-
M1P
mannitol 1-phosphate
-
M1-PDH
mannitol 1-phosphate dehydrogenase
-
PEP
phosphoenolpyruvate
-
PFK
phosphofructokinase
-
PK
pyruvate kinase
-
PTS
phosphotransferase system
-
SCFA
short-chain fatty acid(s)
-
TFA
trifluoroacetic acid 相似文献
6.
Phosphomannomutase (PMM) activity was detected in the soluble cytoplasmic fraction of crude extracts of both mucoid (alginate-producing) and nonmucoid strains ofPseudomonas aeruginosa. The enzyme activity was concentrated and partially purified from cell extracts of mucoid strain V388 by precipitation with ammonium sulfate and by molecular exclusion chromatography. These preparations catalyzed the conversion of mannose 1-phosphate to mannose 6-phosphate in a coupled assay system that contained commercial phosphomannoisomerase, phosphoglucoisomerase, and glucose 6-phosphate dehydrogenase. Catalytic activity in this system was strictly dependent on the presence of glucose 1,6-diphosphate (apparent Km, 150 M) and exhibited a pH optimum of around 9 in Bicine-NaOH buffer. PMM exhibited an apparent Km of 60 M for mannose 1-phosphate, but concentrations greater than 150 M caused significant inhibition. Specific activities of PMM were consistently higher in the soluble fractions of mucoid strains (1.2–3.6 nmol/min/mg protein) than of nonmucoid strains (0.2–0.6 nmol/min/mg protein). 相似文献
7.
W. P. Low K. W. Peng S. K. Phuan C. Y. Lee Y. K. Ip 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(6):487-494
A comparison of branchial enzyme profiles indicates that the gills of Periophthalmodon schlosseri would have a greater capacity for energy metabolism through glycolysis than those of Boleophthalmus boddaerti. Indeed, after exposure to hypoxia, or anoxia, there were significant increases in the lactate content in the gills of P. schlosseri. In addition, exposure to hypoxia or anoxia significantly lowered the glycogen level in the gills of this mudskipper. It can be deduced from these results that the glycolytic flux was increased to compensate for the decrease in ATP production through anaerobic glycolysis. Different from P. schlosseri, although there was an increase in lactate production in the gills of B. boddaerti exposed to hypoxia, there was no significant change in the branchial glycogen content, indicating that a reversed Pasteur effect might have occurred under such conditions. In contrast, anoxia induced an accumulation of lactate and a decrease in glycogen in the gills of B. boddaerti. Although lactate production in the gills of these mudskippers during hypoxia was inhibited by iodoacetate, the decreases in branchial glycogen contents could not account for the amounts of lactate formed. The branchial fructose-2,6-bisphosphate contents of these mudskippers exposed to hypoxia or anoxia decreased significantly, leaving phosphofructokinase and glycolytic rate responsive to cellular energy requirements under such conditions. The differences in response in the gills of B. boddaerti and P. schlosseri to hypoxia were possibly related to the distribution of phosphofructokinase between the free and bound states.Abbreviations ADP
adenosine diphosphate
- ALD
aldolase
- ALT
alanine transaminase
- AST
aspartate transaminase
- ATP
adenosine triphosphate
- CS
citrate synthase
- EDTA
ethylenediaminetetra-acetic acid
- EGTA
ethylene glycol tetra-acetic acid
- F6P
fructose-6-phosphate
- F-1,6-P2
fructose-1,6-bisphosphate
- F-2,6-P2
fructose-2,6-bisphosphate
- FBPase
fructose-1,6-bisphosphatese
- GAPDH
glyceraldehyde-3-phosphate dehydrogenase
- GDH
glutamate dehydrogenase
- -GDH
-glycerophosphate dehydrogenase
- GPase
glycogen phosphorylase
- HK
hexokinase
- HOAD
3-hydroxyacyl-CoA dehydrogenase
- IDH
isocitrate dehydrogenase
- IOA
iodoacetic acid
- LDH
lactate dehydrogenase
- LO
lactate oxidizing activity
- MDH
malate dehydrogenase
- 3-PG
3-phosphoglyceric acid
- PEP
phosphoenolpyruvate
- PEPCK
phosphoenolpyruvate carboxykinase
- PGI
phosphoglucose isomerase
- PGK
phosphoglycerate kinase
- PFK
6-phosphofructo-1-kinase
- PIPES
piperazine-N, N-bis-(2-ethanesulphonic acid)
- PK
pyruvate kinase
- PMSF
phenylmethylsulphonyl fluoride
- PR
pyrurate reducing activity
- SE
standard error
- SW
seawater
- TPI
triosephosphate isomerase 相似文献
8.
The kinetic and molecular properties of cyanobacterial glucose-6-phosphate dehydrogenase, partly purified from Anabaena sp. ATCC 27893, show that it undergoes relatively slow, reversible transitions between different aggregation states which differ in catalytic activity. Sucrose gradient centrifugation and polyacrylamide gel electrophoresis reveal three principal forms, with approximate molecular weights of 120 000 (M
1), 240 000 (M
2) and 345 000 (M
3). The relative catalytic activities are: M
1M
2<M
3. In concentrated solutions of the enzyme, the equilibrium favors the more active, oligomeric forms. Dilution in the absence of effectors shifts the equilibrium in favor of the M
1 form, with a marked diminution of catalytic activity. This transition is prevented by a substrate, glucose-6-phosphate, and also by glutamine. The other substrate, nicotinamide adenine dinucleotide phosphate (NADP+), and (in crude cell-free extracts) ribulose-1,5-diphosphate are negative effectors, which tend to maintain the enzyme in the M
1 form. The equilibrium state between different forms of the enzyme is also strongly dependent on hydrogen ion concentration. Although the optimal pH for catalytic activity is 7.4, dissociation to the hypoactive M
1 form is favored at pH values above 7; a pH of 6.5 is optimal for maintenace of the enzyme in the active state. Reduced nicotamide adenine dinucleotide phosphate (NADPH) and adenosine 5-triphosphate (ATP), inhibit catalytic activity, but do not significantly affect the equilibrium state. The relevance of these findings to the regulation of enzyme activity in vivo is discussed.Abbreviations G6PD
glucose-6-phosphate dehydrogenase
- 6PGD
6-phosphogluconate dehydrogenase
- RUDP
ribulose-1,5-diphosphate
- G6P
glucose-6-phosphate
- 6PG
6-phosphogluconate 相似文献
9.
Glucose-6-phosphate dehydrogenase (d-glucose-6-phosphate: NADP+
l-oxidoreductase EC 1.1.1.49) isolated from Paracoccus denitrificans grown on glucose/nitrate exhibits both NAD+-and NADP+-linked activities. Both activities have a pH optimum of pH 9.6 (Glycine/NaOH buffer) and neither demonstrates a Mg2+ requirement. Kinetics for both NAD(P)+ and glucose-6-phosphate were investigated. Phosphoenolpyruvate inhibits both activities in a competitive manner with respect to glucose-6-phosphate. ATP inhibits the NAD+-linked activity competitively with respect to glucose-6-phosphate but has no effect on the NADP+-linked activity. Neither of the two activities are inhibited by 100 M NADH but both are inhibited by NADPH. The NAD+-linked activity is far more sensitive to inhibition by NADPH than the NADP+-linked activity. 相似文献
10.
Robert L. Blake 《Biochemical genetics》1977,15(7-8):785-801
R-1 (1450g) and R-2 (25,000g) liver fractions from T/t
6 and B6CBAF1 hybrid mice were analyzed for their protein content, mitochondria concentrations, and activities of three respiratory-chain enzymes of the mitochondrial inner membrane: cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, E.C. 1.9.3.1), -glycerophosphate dehydrogenase [l-glycerol-3-phosphate: (acceptor) oxidoreductase, E.C. 1.1.99.5], and succinate-cytochrome c reductase. Only cytochrome c oxidase activity, calculated as units per 1010 mitochondria, was significantly lower in both R-1 and R-2 fractions of T/t
6 mice. Cytochrome c oxidase activity varied greatly among T/t
6 mice, as did their liver mitochondria concentrations and body weights. Cytochrome c oxidase activity in the R-1 fraction of T/t
6 mice, calculated as units per 1010 mitochondria per gram of body weight, averaged about 40% lower than in B6CBAF1 mice. -Glycerophosphate dehydrogenase activity was often elevated in T/t
6 mice, particularly in the R-2 fraction. The T/t locus, a complex genetic locus on chromosome 17, may contain genes important to the function and biogenesis of mitochondria.This investigation was supported by institutional funds from the Jackson Laboratory and by an allocation from NIH Biomedical Research Support Grant (RR-05545). The Jackson Laboratory is fully accredited by the American Association for Accreditation of Laboratory Animal Care. 相似文献
11.
Bacteroids of R. leguminosarum MNF3841 isolated from pea nodules using Percoll gradients had activities of TCA cycle enzymes up to 6-fold higher than those measured in free-living cells grown on fumarate or sucrose. Activities of sugar catabolic enzymes on the other hand were 2–14-fold lower in isolated bacteroids than in sucrose-grown free-living cells. In continuous culture, cells of strain MNF3841 grown on sucrose under P
i limitation had 2–3-fold higher activities of invertase, glucose-6-phosphate dehydrogenase, the Entner-Doudoroff enzymes and 6-phosphogluconate dehydrogenase, than cells grown on fumarate. With one exception O2 limited cultures had similar activities of the carbon catabolic enzymes to P
i-limited cultures grown in the same substrate. Glucose-6-phosphate dehydrogenase in O2-limited cells grown of fumarate was 50% lower than in P
i-limited cells. Co-utilization of fumarate and sucrose occurred with chemostat cultures supplied with both under a variety of conditions.Abbreviations E-D
Entner-Doudoroff
- EMP
Embden-Meyerhof-Parnas
- PEPCK
phosphoenolpyruvate carboxy kinase
- HEPES
N-[2-hydroxyethyl]piperazine-N-[2-ethanesulphonic acid] 相似文献
12.
Acquisition of the dark heterotrophic growth capacity on glucose in Plectonema boryanum involves both adaptation and enrichment of a fast-growing genotype. The adaptation includes induction of functions involved in glucose incorporation and increase in glucose-6-phosphate dehydrogenase activity. Photosynthetic products are implicated in the control of both systems. Efficient energy conversion in the dark, as measured by cyanophage multiplication, correlates in time with the increase in potential for glucose incorporation while heterotrophic growth capacity correlates with the increase in glucose-6-phosphate dehydrogenase activity. The lower efficiency of heterotrophic growth compared to photoautotrophic growth is discussed in light of the conservation of the photosynthetic potency in the heterotrophic cells.Abbreviations DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- DTT
dithiothreitol
- G6P
glucose-6-phosphate
- NADP
nicotinamide adenine dinucleotide phosphate
- NTG
N-methyl-N-nitro-N-nitrosoguanidine
- RUDP
ribulose-1,5-diphosphate
- TCA
trichloroacetic acid
Dedicated to Prof. R. Y. Stanier on the occasion of his 60th birthday 相似文献
13.
2-Ketogluconic acid and, to a lesser extent, gluconic acid were found to be major products of glucose catabolism by phosphate-limited cultures of Klebsiella aerogenes NCTC 418, and together accounted for up to 46% of the glucose carbon that was metabolized.Although the concentrations of both acids increased sub-stantially at low growth rates, their specific rates of synthesis decreased markedly, as did the proportion of glucose converted into these products.Determination of the affinity constant, for glucose, of phosphate-limited organisms showed it to be not significantly different from that of glucose-limited organisms (K
s
50 M), indicative of the phosphotransferase uptake system. And since these organisms possessed an active glucose 6-phosphate dehydrogenase, and had no detectable glucose dehydrogenase activity, it was concluded that gluconic acid and 2-ketogluconic acid arose from their corresponding phosphorylated metabolites, and not directly from glucose. 相似文献
14.
(i) Sucrose-phosphate synthase (SPS) was purified 40-fold from stored potato (Solanum tuberosum L.) tubers to a final specific activity of 33–70 nkat·(mg protein)–1 via batch elution from diethylaminoethyl (DEAE)-sephacel, polyethylene glycol (PEG) precipitation and Mono Q anion-exchange chromatography. (ii) Immunoblotting revealed a major and a minor band with molecular weights of 124.8 kDa and 133.5 kDa, respectively. Both bands were also present in extracts prepared in boiling SDS to exclude proteolysis. No smaller polypeptides were seen, except when the preparations were incubated before application on a polyacrylamide gel. (iii) The enzyme preparation was activated by glucose-6-phosphate and inhibited by inorganic phosphate. Both effectors had a large effect on the K
m (fructose-6-phosphate) and the K
m (uridine-5-diphosphoglucose) with phosphate acting antagonistically to glucose-6-phosphate. (iv) Preincubation of potato slices with low concentrations of okadaic acid or microcystin resulted in a three- to fourfold decrease in the activity of SPS when the tissue was subsequently extracted and assayed. The decrease was especially marked when the assay contained low concentrations of substrates and glucose-6-phosphate, and inorganic phosphate was included. Preincubation with mannose or in high osmoticum resulted in an increase of SPS activity. (v) Analogous changes were observed in germinating Ricinus communis L. seedlings. After preincubation of the cotyledons in glucose, high SPS activity could be measured, whereas okadaic acid, omission of glucose, or addition of phosphate or sucrose led to a large decrease of SPS activity in the selective assay. (vi) It is argued that SPS from non-photosynthetic tissues is regulated by metabolites and by protein phosphorylation in an analogous manner to the leaf enzyme.Abbreviations Fru6P
fructose-6-phosphate
- Glc6P
glucose-6-phosphate
- Pi
inorganic phosphate
- PGI
phosphoglucose isomerase
- PP2A
phosphoprotein phosphatase 2A
- PEG
polyethyleneglycol
- SPS
sucrose-phosphate synthase
- UDPGlc
uridine-5-diphosphoglucose
This work was supported by the Deutsche Forschungsgemeinschaft, the BMFT and Sandoz AG, Basel, Switzerland. We are grateful to Prof. E. Beck (Pflanzenphysiologie, Bayreuth, Germany) for providing us with laboratory facilities, and to Dr. U. Sonnewald (Institut für Genbiologische Forschung, Berlin, Germany) for many discussions and providing us with unpublished data. 相似文献
15.
Ute Höötmann Bernward Bisping Hans-Jürgen Rehm 《Applied microbiology and biotechnology》1991,35(2):258-263
Summary Some physiological data of cells of Pichia farinosa immobilized on sintered glass Raschig rings were compared with data from free cells. Glucose consumption and productivity of total polyols (arabitol, glycerol and erythritol) showed a simultaneous inter-lag phase. Enzymes that catalyse steps of the pentosephosphate pathway (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, transaldolase and polyol dehydrogenase) showed a distinct increase after transfer of the cells into production medium. The activity of glycerol-3-phosphate dehydrogenase was generally low. Only alcohol dehydrogenase presented the inter-lag phase mentioned above.Offprint requests to: H.-J. Rehm 相似文献
16.
Suzanne M. Loret Pierre E. Devos 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(7):651-657
Summary The hydrolysis of glucose-6-phospate in the digestive gland of the crab Carcinus maenas is carried out by an aspecific phosphatase. This enzyme possesses the following features: (1) insensitivity to acid treatment; (2) absence of inhibition when exposed to citrate at low pH; (3) similar affinity for G6P as the acid phosphatase for Na--glycerophosphate (K
m 2.3 and 2.0 mM, respectively). Glucose-6-phosphate and Na--glycerophate hydrolysis reactions seem to be catalysed by the same enzyme, since both activities exhibit the same distribution in a subcellular fractionation of the gland. Furthermore, as these activities are principally recovered in the subcellular fraction enriched in calcospherites (or calcium phosphate granules), it is proposed that the aspecific G6P-phosphohydrolase could play a major role in the formation of these granules. The phosphorylation of glucose is made by two low K
m hexokinases (230 and 64 M, respectively). As their level of activity shows significant changes over the moult cycle, these enzymes could be considered as having a regulatory role in the storage of glucose in the digestive gland.Abbreviations Acid Pase
aspecific acid phosphatase
- ATP
adenosine triphosphate
- DTT
dithiothreitol
- EDTA
ethylenediaminetetra-acetate
- G
calcium phosphate granules fraction
- G6P
glucose-6-phosphate
- G6Pase
hepatic glucose-6-phosphatase
- G6PDH
glucose-6-phosphate dehydrogenase
-
K
m
Michaelis-Menten constant
- MI
mitochondria and intermediate postmitochondrial particles
- N
nuclei fraction
- NADH
nicotineamide adenine dinucleotide
- P
microsome fraction
- Pi
inorganic phosphate
- PMSF
phenylmethylsulphonylfluoride
- STI
soybean trypsin inhibitor
- glyP
Na--glycerophosphate
- T1,2,3
transport protein 1,2,3
- TCA
trichloroacetic acid 相似文献
17.
ORF MJ1605, previously annotated as pgi and coding for the putative glucose-6-phosphate isomerase (phosphoglucose isomerase, PGI) of the hyperthermophilic archaeon Methanococcus jannaschii, was cloned and functionally expressed in Escherichia coli. The purified 80-kDa protein consisted of a single subunit of 45 kDa, indicating a homodimeric (2) structure. The K
m values for fructose 6-phosphate and glucose 6-phosphate were 0.04 mM and 1 mM, the corresponding V
max values were 20 U/mg and 9 U/mg, respectively (at 50 °C). The enzyme had a temperature optimum at 89 °C and showed significant thermostability up to 95 °C. The enzyme was inhibited by 6-phosphogluconate and erythrose-4-phosphate. RT-PCR experiments demonstrated in vivo expression of ORF MJ1618 during lithoautotrophic growth of M. jannaschii on H2/CO2. Phylogenetic analyses indicated that M. jannaschii PGI was obtained from bacteria, presumably from the hyperthermophile Thermotoga maritima. 相似文献
18.
During growth on glycerol two marine Desulfovibrio strains that can grow on an unusually broad range of substrates contained high activities of glycerol kinase, NAD(P)-independent glycerol 3-phosphate dehydrogenase and the other enzymes necessary for the conversion of dihydroxyacetone phosphate to pyruvate. Glycerol dehydrogenase and a specific dihydroxyacetone kinase were absent. During growth on dihydroxyacetone, glycerol kinase is involved in the initial conversion of this compound to dihydroxyacetone phosphate which is then further metabolized. Some kinetic properties of the partially purified glycerol kinase were determined. The role of NAD as electron carrier in the energy metabolism during growth of these strains on glycerol and dihydroxyacetone is discussed.Glycerol also supported growth of three out of four classical Desulfovibrio strains tested. D. vulgaris strain Hildenborough grew slowly on glycerol and contained glycerol kinase, glycerol 3-phosphate dehydrogenase and enzymes for the dissimilation of dihydroxyacetone phosphate. In D. gigas which did not grow on glycerol the enzymes glycerol kinase and glycerol 3-phosphate dehydrogenase were absent in lactate-grown cells.Abbreviations DHA
dihydroxyacetone
- DHAP
dihydroxyacetone phosphate
- G3P
glycerol 3-phosphate
- GAP
glyceraldehyde 3-phosphate
- 3-PGA
3-phosphoglycerate
- 2-PGA
2-phosphoglycerate
- 2,3-DPGA
2,3-diphosphoglycerate
- PEP
phosphoenolpyruvate
- DH
dehydrogenase
- GK
glycerol kinase
- DHAK
dihydroxyacetone kinase
- TIM
triosephosphate isomerase
- PGK
3-phosphoglycerate kinase
- PK
pyruvate kinase
- LDH
lactate dehydrogenase
- DTT
dithiotreitol
- HEPES
4-(2-hydroxyethyl)-1-piperazine ethane sulfonic acid
- PIPES
piperazine-1,1-bis(2-ethane sulfonic acid)
- BV2+/BV+
oxidized/reduced benzylviologen
- PMS
phenazine methosulfate
- DCPIP
2,6-dichlorophenolindophenol
- MTT
3-(4,5-dimethylthiazol-2-yl)-2,4-diphenyltetrazolium bromide 相似文献
19.
l-myo-Inositol 1-phosphate synthase (EC 5.5.1.4; MIPS) catalyzes conversion of glucose 6-phosphate to l-myo-inositol 1-phosphate, the first and the rate-limiting step in the production of inositol, and has been reported from evolutionarily diverse organisms. Two forms of the enzyme have been characterized from higher plants, viz. cytosolic and chloroplastic, and the presence of MIPS has been earlier reported from the cyanobacteria (e.g. Spirulina sp.), the presumed chloroplast progenitors. The present study demonstrates possible multiple forms of MIPS and identifies the gene for one of them in the cyanobacterium Synechocystis sp. PCC 6803. Following detection of at least two immunologically cross-reactive MIPS forms, we have been able to identify from the fully sequenced Synechocystis genome an as yet unassigned open reading frame (ORF), sll1722, coding for the approx. 50-kDa MIPS protein, by using biochemical, molecular and bioinformatics tools. The DNA fragment corresponding to sll1722 was PCR-amplified and functional identity of the gene was confirmed by a complementation assay in Saccharomyces cerevisiae mutants containing a disrupted INO1 gene for the yeast MIPS. The sll1722 PCR product was cloned in Escherichia coli expression vector pET20b and the isopropyl -d-thiogalactopyranoside (IPTG)-induced overexpressed protein product was characterized following complete purification. Comparison of the sll1722 sequences with other MIPS sequences and its phylogenetic analysis revealed that the Synechocystis MIPS gene is quite divergent from the others.Abbreviations
CBB
Coomassie Brilliant Blue
-
EST
Expressed sequence tag
-
G6P
d-Glucose 6-phosphate
- IPTG
Isopropyl -d-thiogalactopyranoside
-
MIPS
l–myo-Inositol 1-phosphate synthase
- ORF
Open reading frame 相似文献
20.
Hainan Gu 《Biochemical genetics》1991,29(7-8):345-354
Variations at three flight-related enzyme loci, -glycerophosphate dehydrogenase (-Gpdh), glucose-6-phosphate dehydrogenase (G6pd), and phosphoglucomutase (Pgm), ofEpiphyas postvittana (Walker) moths were investigated using starch gel electrophoresis. Among the three enzyme loci, -Gpdh andG6pd were found to be monomorphic, butPgm was polymorphic, with a total of seven different genotypes and five alleles identified in this study. Comparisons of allozyme variability at thePgm locus showed significant differentiation among five natural populations sampled from geographically distinct localities in New Zealand and Australia and between laboratory populations differentiated by artificial selection on flight capacity. ThePgm polymorphism was shown to be associated with the variation of flight capacity, but the role of the enzyme locus in the evolution of flight behavior is to be demonstrated in this species.This work was supported by the research scholarship of the University of New England. 相似文献