Induction of the xylitol dehydrogenase of Pullularia pullulans

1988 ◽  
Vol 34 (2) ◽  
pp. 107-111 ◽  
Author(s):  
Juliet K. Sugai ◽  
L. A. Veiga
Keyword(s):  
Enzyme Induction ◽  
De Novo ◽  
Specific Activity ◽  
Kinetic Studies ◽  
Xylitol Dehydrogenase ◽  
Lag Phase ◽  
Differential Rate ◽  
De Novo Synthesis ◽  
Induction Study ◽  
Glycerol Medium

Pullularia pullulans, a yeastlike fungus, metabolizes xylitol via an intracellular xylitol dehydrogenase. Formation of the enzyme was induced by D-xylose and inhibited by cycloheximide, suggesting de novo synthesis. The induction study was carried out with noninduced cells of P. pullulans harvested from a glycerol medium. The cells initiated synthesis of xylitol dehydrogenase without a detectable lag phase when 1.5% xylose was added. The differential rate of xylitol dehydrogenase synthesis was 1.4 units per mg of synthesized protein. Kinetic studies of enzyme induction in a growing culture showed that the highest level of specific activity was reached at 25 to 27 h of growth, with an increase of 200 times over the basal level in the glycerol medium.

Rates of de novo Synthesis of Malate Synthase and Albumins during the Very Early Phase of Germination

1979 ◽  
Vol 34 (12) ◽  
pp. 1237-1242 ◽  
Author(s):  
Wolfram Köller ◽  
Helmut Kindl
Keyword(s):  
Early Phase ◽  
De Novo ◽  
Specific Activity ◽  
Specific Radioactivity ◽  
Malate Synthase ◽  
Polyacrylamide Gel ◽  
De Novo Synthesis ◽  
Albumin Fraction ◽  
Average Value ◽  
Large Pool

Abstract Malate synthase is synthesized de novo in the very early phase of germination. Its molecular and immunological properties do not differ from those of malate synthase from fully developed cotyledons. Radioactive leucine was administered to dry seeds of cucumber, and its incorporation into proteins of cotyledons was examined after 2 days of germination. The specific radioactivity of malate synthase, purified by immunoprecipitation and electrophoresis on polyacrylamide gel, was only 1/20 the average value of the total albumin fraction. The minimal incorporation documented by the comparatively low specific activity of isolated malate synthase is discussed in relation to the large pool of malate synthase already present in dry seeds.

scholarly journals Sphingolipid Profiling Reveals Different Extent of Ceramide Accumulation in Bovine Retroperitoneal and Subcutaneous Adipose Tissues

Metabolites ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 473
Author(s):  
Yue Hei Leung ◽  
Sonja Christiane Bäßler ◽  
Christian Koch ◽  
Theresa Scheu ◽  
Ulrich Meyer ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
De Novo ◽  
Specific Activity ◽  
Multiple Reaction Monitoring ◽  
De Novo Synthesis ◽  
Bioactive Lipids ◽  
Tissue Specific ◽  
Sphingosine 1 Phosphate ◽  
Ceramide Accumulation ◽  
Subcutaneous Adipose

Sphingolipids are bioactive lipids that can modulate insulin sensitivity, cellular differentiation, and apoptosis in a tissue-specific manner. However, their comparative profiles in bovine retroperitoneal (RPAT) and subcutaneous adipose tissue (SCAT) are currently unknown. We aimed to characterize the sphingolipid profiles using a targeted lipidomics approach and to assess whether potentially related sphingolipid pathways are different between SCAT and RPAT. Holstein bulls (n = 6) were slaughtered, and SCAT and RPAT samples were collected for sphingolipid profiling. A total of 70 sphingolipid species were detected and quantified by UPLC-MS/MS in multiple reaction monitoring (MRM) mode, including ceramide (Cer), dihydroceramide (DHCer), sphingomyelin (SM), dihydrosphingomyelin (DHSM), ceramide-1-phosphate (C1P), sphingosine-1-phosphate (S1P), galactosylceramide (GalCer), glucosylceramide (GluCer), lactosylceramide (LacCer), sphinganine (DHSph), and sphingosine (Sph). Our results showed that sphingolipids of the de novo synthesis pathway, such as DHSph, DHCer, and Cer, were more concentrated in RPAT than in SCAT. Sphingolipids of the salvage pathway and the sphingomyelinase pathway, such as Sph, S1P, C1P, glycosphingolipid, and SM, were more concentrated in SCAT. Our results indicate that RPAT had a greater extent of ceramide accumulation, thereby increasing the concentration of further sphingolipid intermediates in the de novo synthesis pathway. This distinctive sphingolipid distribution pattern in RPAT and SCAT can potentially explain the tissue-specific activity in insulin sensitivity, proinflammation, and oxidative stress in RPAT and SCAT.

Accumulation of Proline and Sucrose during the First Hours after Transfer of Chlorella emevsonii to High NaCl

1979 ◽  
Vol 6 (1) ◽  
pp. 69 ◽  
Author(s):  
H Greenway ◽  
T.L Setter
Keyword(s):  
Steady State ◽  
Osmotic Potential ◽  
De Novo ◽  
Lag Phase ◽  
Sucrose Synthesis ◽  
De Novo Synthesis ◽  
Subsequent Period ◽  
Osmotic Solutes ◽  
Steady State Levels ◽  
Osmotic Solute

Net synthesis of proline, the main osmotic solute in C. emersonii, showed a lag of at least 15 min following transfer of cells from 1 m~ NaCl to concentrations ranging between 25 and 335 m~ NaCl. During the subsequent period of rapid net proline synthesis, the maximum rates were approximately linearly related to the decreases in external osmotic potential (YJ until the cells plasmolysed. Beyond the point of incipient plasmolysis, further large decreases in Y* did not change the maximum rates of proline synthesis. The steady-state levels of proline were lower, and were reached faster, the smaller the decreases in external Ys. Overall these results support the notion that turgor potential has a regulating role in the synthesis of osmotic solutes. Sucrose synthesis showed no lag and was rapid even in plasmolysed cells. Cycloheximide inhibited formation of proline but not of sucrose. This, together with the lag phase of 15 min in proline synthesis, indicated that transfer of C. emersonii to high NaCl induced de novo synthesis of enzymes involved in proline formation. Effects of DCMU and darkness were also measured. Cells transferred to 125 m~ NaCl still showed substantial net synthesis of sucrose, but not of proline. Supply of glucose in the dark did not lead to proline formation, but it did stimulate proline synthesis which occurred when glutamate was supplied.

Enhanced RNA and protein synthesis in adipose tissue of rats adapted to periodic hyperphagia

1968 ◽  
Vol 46 (6) ◽  
pp. 903-906 ◽  
Author(s):  
L. Kazdová ◽  
T. Braun ◽  
P. Fábry ◽  
R. Poledne
Keyword(s):  
Protein Synthesis ◽  
Adipose Tissue ◽  
Rna Synthesis ◽  
De Novo ◽  
Specific Activity ◽  
De Novo Synthesis ◽  
Experimental Conditions ◽  
Rna And Protein Synthesis ◽  
Meal Feeding ◽  
The Difference

RNA synthesis measured by the incorporation of orotic acid-6-14C into RNA was investigated in isolated adipose tissue of control rats and of rats adapted to periodic hyperphagia, evoked by meal-feeding (a single 2-h meal per day). Both groups were fasted for 22 h and subsequently fed a measured test meal for another 2 h. It was revealed that 2 and 4 h after feeding there was no significant change in comparison with values during fasting, whereas in tissue of meal-fed rats the specific activity of RNA gradually increased by 22% and 41% respectively. The difference between controls and meal-fed rats was even much more marked if the specific activity of RNA in fat cells, isolated after incubation of the tissue, was measured. A significantly greater response of meal-fed rats was found when protein synthesis and lipogenesis in adipose tissue were assessed under the same experimental conditions. The possibility is discussed that the enhanced RNA and protein synthesis in adipose tissue of meal-fed rats is associated with de novo synthesis of enzymes involved in adaptive hyperlipogenesis.

scholarly journals DRES-09. REGULATORY EFFECTS OF THE CILIARY GTPASE ARL13B ON PURINE METABOLISM IN GBM

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi73-vi73
Author(s):  
Miranda Saathoff ◽  
Jack Shireman ◽  
Eunus Ali ◽  
Cheol Park ◽  
Issam Ben-Sahra ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
De Novo ◽  
Specific Activity ◽  
Purine Metabolism ◽  
P Value ◽  
Salvage Pathway ◽  
De Novo Synthesis ◽  
Dna Double Strand Breaks ◽  
Purine Nucleotides ◽  
Regulatory Effects

Abstract Glioblastoma (GBM) is the most common form of adult primary brain cancer. Despite an aggressive treatment regimen – surgical resection, irradiation, and temozolomide (TMZ) chemotherapy – patients’ prognosis is still grim. TMZ acts by methylating purines, specifically at the O6 and N7 positions of guanine, to induce cytotoxic DNA double-strand breaks. We thus wanted to explore how purine metabolism may contribute to TMZ-resistance. In mammalian cells, purine nucleotides can be recycled by the salvage pathway or generated via de novo synthesis. The salvage pathway is energetically inexpensive relative to de novo thus, highly proliferative GBM cells preferentially utilize the salvage pathway. We have shown that salvage synthesis is reduced in response to TMZ (p-value=0.0021), hinting that the cells may utilize de novo to evade therapy induced alkylation of purines. Using immunoprecipitation-mass spectroscopy analysis, we found a novel interaction between the ciliary GTPase ARL13B and IMPDH2, the rate-limiting enzyme in de novo synthesis. We have shown that this interaction, occurring at the C-terminal domain of ARL13B, plays a significant role in the regulation of purine biosynthesis as abolishing it through ARL13B knockdown reduced flux through de novo (p-value< 0.0001) synthesis as measured by the specific activity of IMPDH2. Further, the lentiviral-mediated rescue of ARL13B brings IMPDH2 activity back to basal levels (p< 0.0001). Given its canonical function as a GTPase, we hypothesize that ARL13B acts as a novel regulator of de novo synthesis by sequestering GDP, allowing IMPDH2 to sense and respond to the cytosolic levels of guanine nucleotides. Without ARL13B the de novo pathway is halted, forcing the cells to rely on salvage to replenish nucleotide pools. Reliance on this pathway in the presence of TMZ causes cells to incorporate damaged nucleotides as a result of the drug’s alkylating action leading to the increased therapeutic efficacy of TMZ.

Structural and Metabolic Interrelationships Among Glycerophosphatides of Rat Liver In Vivo

1971 ◽  
Vol 49 (12) ◽  
pp. 1347-1356 ◽  
Author(s):  
B. J. Holub ◽  
A. Kuksis
Keyword(s):  
Rat Liver ◽  
De Novo ◽  
Specific Activity ◽  
Acyl Transfer ◽  
De Novo Synthesis ◽  
Individual Molecular Species ◽  
Relative Specific Activity ◽  
Proportional Contribution ◽  
Specific Activities

The specific activities of individual molecular species of rat liver diacylglycerylphosphorocholine (PC), diacylglycerylphosphoroethanolamine (PE), and diacylglycerophosphorylinositol (MPI) were determined and compared following intravenous injection of glycerol-14C. PC, PE, and MPI contained 41, 51, and 83%, respectively, tetraenoic species, and 40,17, and 9% combined mono-, di-, and trienoic species. The rest of the phosphatide mass of PC, PE, and MPI was contributed by 18, 32, and 8% penta- and hexaenoic species, respectively. The proportions of chemical classes of the glycerophosphatides differed by 1.1- to 18-fold while the fatty acid associations within the unsaturation classes common to these phosphatides varied 2.2- to 17-fold. After 5 min exposure to radioactive glycerol, the mono-, di-, and trienoic species of the PC, PE, and MPI possessed 13–18, 15–50, and 6–42 times, respectively, the specific activity of the tetraenes of the corresponding phosphatide classes. While the pentaenoic and hexaenoic species of PC and MPI had specific activities three to five times those of the respective tetraenes, the higher polyenes of PE were considerably more radioactive and approached the specific activity of the dienoic species of this phosphatide. With progressing time up to 60 min, the tetraenoic species of PC, PE, and MPI showed increases in relative specific activity of 50, 64, and 109%, respectively, in the three phosphatides. These results are consistent with an effective de novo synthesis of the oligoenoic species and a transacylation of the tetraenoic species of all liver glycerophosphatides tested. The proportional contribution of de novo synthesis in comparison to acyl transfer is apparently greater to the formation of PC and PE than to that of MPI.

The occurrence of a soluble glucose 6-phosphatase in cotyledon tissue of Phaseolus vulgaris during germination

1969 ◽  
Vol 47 (7) ◽  
pp. 685-689 ◽  
Author(s):  
J. E. Thompson
Keyword(s):  
Endoplasmic Reticulum ◽  
Phaseolus Vulgaris ◽  
De Novo ◽  
Specific Activity ◽  
Soluble Fraction ◽  
Soluble Form ◽  
Soluble Enzyme ◽  
De Novo Synthesis ◽  
Soluble Enzymes ◽  
Ph Profiles

Cotyledon tissue from seedlings of Phaseolus vulgaris at various stages of germination was homogenized and fractionated under isotonic conditions. Measurement of glucose 6-phosphatase (D-glucose 6-phosphate phosphohydrolase, EC 3.1.3.9) activity in the isolated fractions showed an increase in the level of soluble enzyme with advancing age of the cotyledons, such that by late senescence (10 days of age) approximately 90% of the recovered glucose 6-phosphatase was present in the soluble fraction, and its specific activity was about twofold greater than that of the homogenate. The pH profiles of the bound and soluble enzymes were found to be closely similar. The presence of a soluble glucose 6-phosphatase has been interpreted as indicating either de novo synthesis of the soluble form of the enzyme with advancing senescence, or solubilization of normally bound enzyme which may in turn reflect a partial breakdown in the structure of endoplasmic reticulum in senescent cells.

The mechanism of de novo synthesis of fructooligosaccharides in leaf disks of certain Asteraceae. III.

1974 ◽  
Vol 52 (1) ◽  
pp. 181-188 ◽  
Author(s):  
K. R. Chandorkar ◽  
F. W. Collins
Keyword(s):  
De Novo ◽  
Specific Activity ◽  
Jerusalem Artichoke ◽  
De Novo Synthesis ◽  
Jerusalem Artichoke Tuber ◽  
Exogenous Substrate ◽  
Endogenous Substrate ◽  
Leaf Disks ◽  
Tracer Experiments

14C-tracer experiments revealed that both endogenous and exogenous substrate was incorporated in the fructosans synthesized in leaf disks during incubation on phosphate-buffered sugar media. At least some of the endogenous substrate was derived from a source which was insoluble in 80% ethanol at the start of the incubation period. Endogenous and exogenous substrates were distributed in the fructosans in a pattern which was qualitatively similar regardless of the type of sugar supplied exogenously. A complex relationship was exhibited between the specific activity of various fructosan oligomers, expressed on a gram basis, and their chain length. However, expressed on a molar basis, the specific activity of the fructosyl tail portion of each homolog appeared to be linearly related to the number of hexosyl residues that it contained. Such a relationship suggests that enzymes similar to the Jerusalem artichoke tuber transfructosylases are present in leaf disk tissue after 72 h incubation and indeed may function in the de novo synthesis of fructosans in vivo.

scholarly journals PhaM Is the Physiological Activator of Poly(3-Hydroxybutyrate) (PHB) Synthase (PhaC1) in Ralstonia eutropha

2013 ◽  
Vol 80 (2) ◽  
pp. 555-563 ◽  
Author(s):  
Daniel Pfeiffer ◽  
Dieter Jendrossek
Keyword(s):  
De Novo ◽  
Ralstonia Eutropha ◽  
Specific Activity ◽  
High Specific Activity ◽  
Size Exclusion ◽  
Lag Phase ◽  
Granule Formation ◽  
Content Type ◽  
Phb Synthase

ABSTRACTPoly(3-hydroxybutyrate) (PHB) synthase (PhaC1) is the key enzyme of PHB synthesis inRalstonia eutrophaand other PHB-accumulating bacteria and catalyzes the polymerization of 3-hydroxybutyryl-CoA to PHB. Activity assays ofR. eutrophaPHB synthase are characterized by the presence of lag phases and by low specific activity. It is assumed that the lag phase is caused by the time necessary to convert the inactive PhaC1 monomer into the active dimeric form by an unknown priming process. The lag phase can be reduced by addition of nonionic detergents such as hecameg [6-O-(N-heptyl-carbamoyl)-methyl-α-d-glucopyranoside], which apparently accelerates the formation of PhaC1 dimers. We identified the PHB granule-associated protein (PGAP) PhaM as the natural primer (activator) of PHB synthase activity. PhaM was recently discovered as a novel type of PGAP with multiple functions in PHB metabolism. Addition of PhaM to PHB synthase assays resulted in immediate polymerization of 3HB coenzyme A with high specific activity and without a significant lag phase. The effect of PhaM on (i) PhaC1 activity, (ii) oligomerization of PhaC1, (iii) complex formation with PhaC1, and (iv) PHB granule formationin vitroandin vivowas shown by cross-linking experiments of purified proteins (PhaM, PhaC1) with glutardialdehyde, by size exclusion chromatography, and by fluorescence microscopic detection ofde novo-synthesized PHB granules.

Evidence that hepatic triglycerides provide acylglycerides for synthesis of bile phosphatidylcholines

1994 ◽  
Vol 267 (6) ◽  
pp. G1028-G1034
Author(s):  
G. M. Patton ◽  
J. M. Fasulo ◽  
S. J. Robins
Keyword(s):  
Fatty Acid ◽  
Phosphatidic Acid ◽  
Rat Liver ◽  
De Novo ◽  
Specific Activity ◽  
De Novo Synthesis ◽  
Chase Period ◽  
Phosphatidic Acids

To determine the biochemical origin of bile phosphatidylcholines (PCs), rat liver perfusions with 16:1 fatty acid (FA) and [3H]glycerol were performed to generate novel radiolabeled bile and liver PCs and their hepatic glyceride precursors. Results showed total equilibration of bile and liver 16:1-16:1 PC when the specific activity of precursor glycerol-3-phosphate was kept constant. However, when the specific activity of glycerol-3-phosphate decreased during the labeling period and during a prolonged chase period with 17:1 FA and nonradiolabeled glycerol, the specific activity of bile 16:1-16:1 PC was appreciably higher than this same PC in the liver and during the chase period was even higher than its hepatic 16:1-16:1 acylglycerol precursors, phosphatidic acid and diglyceride. During the chase period with 17:1 FA, new radiolabeled 16:1-17:1 PC was formed, and again the specific activity of this PC in bile was greater than this PC and 16:1-17:1 phosphatidic acid and diglyceride in the liver. Only the specific activity of liver 16:1-16:1-(FA) triglyceride equaled or was high enough to support the formation of new bile 16:1-16:1 PC. These studies indicate that bile PCs do not directly derive from preexisting hepatic PCs or by de novo synthesis through phosphatidic acids and diglycerides, but likely originate by remodeling from a pool of hepatic triglycerides.

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