scholarly journals Control of isocitrate lyase synthesis in Chlorella fusca var. vacuolata. The basal activity of the enzyme and the kinetics of induction

1977 ◽  
Vol 164 (1) ◽  
pp. 147-151 ◽  
Author(s):  
C F Thurston
Keyword(s):  
Catabolite Repression ◽  
Photosynthetic Activity ◽  
Isocitrate Lyase ◽  
Fold Increase ◽  
Enzyme Synthesis ◽  
Autotrophic Growth ◽  
Chlorella Fusca ◽  
Basal Activity ◽  
Lyase Activity ◽  
Kinetics Of

1. Isocitrate lyase activity was measured in non-induced Chlorella fusca var. vacuolata cells. 2. During exponential autotrophic growth about 1-2 molecules of the enzyme per cell were present. 3. In light-limited cultures the amount of the enzyme increased to 10-20 molecules/cell. 4. When autotrophic cultures were placed in the dark, the basal activity of isocitrate lyase increased after a 2h lag so that after 8h in the dark there was a 500-fold increase in activity. 5. When isocitrate lyase was induced (by addition of acetate and removal of illumination) in autotrophic cultures which had been growing exponentially, the full induced rate of enzyme synthesis was obtained after 70-80min. 6. When light-limited autotrophic cultures were induced, the rate of isocitrate lyase synthesis was maximal after only 40-50min. 7. These data are consistent with a catabolite-repression control co-ordinated with photosynthetic activity, which may be independent of the specific inducing effect of acetate.

scholarly journals Control of isocitrate lyase synthesis in Chlorella fusca var. vacuolata. Rate of enzyme synthesis in the presence and absence of acetate measured by [35S]methionine labelling and immunoprecipitation

1978 ◽  
Vol 176 (1) ◽  
pp. 179-185 ◽  
Author(s):  
S M Dunham ◽  
C F Thurston
Keyword(s):  
Isocitrate Lyase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Enzyme Synthesis ◽  
Acetate Incorporation ◽  
Enzyme Protein ◽  
Chlorella Fusca ◽  
Rate Of Increase ◽  
Lyase Activity ◽  
Presence And Absence

The rate of increase of isocitrate lyase activity was measured in darkened Chlorella fusca var. vaculoata cultures in the presence and absence of acetate and compared with the rate of incorporation of [35S]methionine into isocitrate lyase enzyme protein under the same conditions. Isocitrate lyase enzyme protein was isolated for this purpose by specific immunoprecipitation and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. After 4h in the dark, in the presence of acetate the rate of increase of isocitrate lyase activity was 75 times that in the absence of acetate. Incorporation of [35S]methionine into isocitrate lyase was 140 times greater in the presence of acetate. Incorporation of [35S]methionine into the trichloroacetic acid-insoluble fraction overall was about five times as fast in the presence of acetate. These data are not consistent with an increased turnover of isocitrate lyase enzyme molecules, sufficient to account for the low rate of increase of isocitrate lyase activity in the absence of acetate. The greater rate of enzyme synthesis in the presence of acetate must therefore be due to some effect of this metabolite on the processing or translation of isocitrate lyase mRNA.

scholarly journals Isocitrate Lyase Activity in Lactobacillus murinus CNRZ 313

1983 ◽  
Vol 66 (6) ◽  
pp. 1232-1236 ◽  
Author(s):  
M.C. Albizzatti de Rivadeneira ◽  
M.C. Manca de Nadra ◽  
A.A. Pesce de Ruiz Holgado ◽  
G. Oliver
Keyword(s):  
Isocitrate Lyase ◽  
Lyase Activity ◽  
Lactobacillus Murinus

Acetate metabolism in Escherichia coli

1978 ◽  
Vol 24 (2) ◽  
pp. 149-153 ◽  
Author(s):  
T. M. Lakshmi ◽  
Robert B. Helling
Keyword(s):  
Isocitrate Dehydrogenase ◽  
Citrate Synthase ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Acetate Metabolism ◽  
Wild Type ◽  
Intermediary Metabolites ◽  
Lyase Activity ◽  
Acetate Medium ◽  
The Glyoxylate Cycle

Levels of several intermediary metabolites were measured in cells grown in acetate medium in order to test the hypothesis that the glyoxylate cycle is repressed by phosphoenolpyruvate (PEP). Wild-type cells had less PEP than either isocitrate dehydrogenase – deficient cells (which had greater isocitrate lyase activity than the wild type) or isocitrate dehydrogenase – deficient, citrate synthase – deficient cells (which are poorly inducible). Thus induction of the glyoxylate cycle is more complicated than a simple function of PEP concentration. No correlation between enzyme activity and the level of oxaloacetate, pyruvate, or citrate was found either. Citrate was synthesized in citrate synthase – deficient mutants, possibly via citrate lyase.

Changes in lipophosphoglycan and gene expression associated with the development ofLeishmania majorinPhlebotomus papatasi

Parasitology ◽  
1995 ◽  
Vol 111 (3) ◽  
pp. 275-287 ◽  
Author(s):  
E. M. B. Saraiva ◽  
P. F. P. Pimenta ◽  
T. N. Brodin ◽  
E. Rowton ◽  
G. B. Modi ◽  
...  
Keyword(s):  
Differential Expression ◽  
Fold Increase ◽  
Surface Expression ◽  
Side Chain ◽  
Surface Coat ◽  
Natural Vector ◽  
Metacyclic Promastigotes ◽  
Kinetics Of

SUMMARYStage-specific molecular and morphogenic markers were used to follow the kinetics of appearance, number, and position of metacyclic promastigotes developing during the course ofL. majorinfection in a natural vector,Phlebotomus papatasi. Expression of surface lipophosphoglycan (LPG) on transformed promastigotes was delayed until the appearance of nectomonad forms on day 3, and continued to be abundantly expressed by all promastigotes thereafter. An epitope associate with arabinose substitution of LPG side-chain oligosaccharides, identified by its differential expression by metacyclics invitro, was detected on the surface of a low proportion of midgut promastigotes beginning on day 5, and on up to 60% of promatigotes on days 10 and 15. In contrast 100% of the parasites egested from the mouthparts during forced feeding of 15 day infected flies stained strongly for this epitope. At each time-point, the surface expression of the modified LPG was restricted to morphologically distinguished metacyclic forms. Ultrastructural study of the metacyclic surface revealed an approximate 2-fold increase in the thickness of the surface coat compared to nectomonad forms, suggesting elongation of LPG as occurs during metacyclogenesisin vitro. A metacyclic-associated transcript (MAT-1), another marker identified by its differential expression invitro, also showed selective expression by promastigotes in the fly, and was used inin situhybridization studies to demonstrate the positioning of metacyclics in the anterior gut.

Transformation of Rana tigrina during Progressive Metamorphosis

2021 ◽  
Vol 30 (1) ◽  
pp. 102-109
Author(s):  
Dhananjay Mishra ◽  
K.Venu Achari
Keyword(s):  
Acid Phosphatase ◽  
Total Protein ◽  
Ribonucleic Acid ◽  
Fold Increase ◽  
Total Activity ◽  
Total Protein Content ◽  
Total Carbohydrate ◽  
Rna Content ◽  
Rana Tigrina ◽  
Kinetics Of

We determined the kinetics of metamorphosis, apoptosis, and tail regression in Rana tigrina. Acid phosphatase activity (µMole Pi.hr-1.tail-1) in the growing and regressing tail attended six to thirty fold increase respectively. However total activity in the trunk was decreased through progressive growing stages of metamorphosis. Total protein content in the trunk of tadpoles at climax stage (XXI) was decrease (35%) from 2.6mg/ml to 1.7mg/ml. The tail of tadpole tissue has shown a two fold increase in total Ribonucleic Acid (RNA) content from stage III to stage XVIII. But there was again decrease in total RNA content at climax stage (stage XXI). This might be possible due to decreased protein synthetic status. When the experiment was performed in trunk homogenate the amount of total carbohydrate (mg/ml) was slightly increased from 37mg/ml to 38.6mg/ml. this might be due to increase in the activity of α-amylase enzymes in the viscera of developing tadpole when it reached the climax stage.

Metabolism of Food Reserves in Germinating Velvetleaf

Weed Science ◽  
1970 ◽  
Vol 18 (5) ◽  
pp. 565-571
Author(s):  
J. A. Mulliken ◽  
C. A. Kust ◽  
L. E. Schrader
Keyword(s):  
Hydrogen Cyanide ◽  
Isocitrate Lyase ◽  
Dry Weight ◽  
Maximal Activity ◽  
Radicle Growth ◽  
Fat Mobilization ◽  
Lyase Activity ◽  
Radicle Emergence ◽  
Weight Protein ◽  
Food Reserves

Endosperm dry weight, protein, and fat losses accompanied rapid radicle growth of velvetleaf (Abutilon theophrasti Medic.) between 12 and 36 hr of germination at 31 C. Cotyledonary reserves were mobilized after 36 hr. Isocitrate lyase activity sedimented with a particulate fraction in varying degrees, but maximal activity developed at times coincident with fat mobilization. Respiration of excised endosperms reached maximal rates shortly after radicle emergence. The actions of hydrogen cyanide, carbon monoxide, and 2,4-dinitrolphenol indicated that respiration of endosperms excised from imbibed and germinated seed was due to cytochrome oxidase activity, and was coupled to phosphorylation.

Platelet adhesion by Subendothelium-Bound Factor VIII-VWF:Kinetics and Molecular Weight Dependence

1979 ◽  
Author(s):  
P. A. Bolhuis ◽  
K. S. Sakariassen ◽  
J. J. Sixma
Keyword(s):  
Molecular Weight ◽  
Platelet Adhesion ◽  
Fold Increase ◽  
Surface Concentration ◽  
Albumin Solution ◽  
Molecular Weight Dependence ◽  
High Molecular Weight Component ◽  
Von Willebrand ◽  
Kinetics Of

Platelet adhesion to human subendothelium was determined by perfusions with albumin solutions containing 51Cr-labeled, aspirin-treated platelets and washed red cells (hematocrit 40%) at 37° and a flow rate of 135 ml/min. Adherence was similar with Von Willebrand plasma instead of albumin solution and addition of purified FVIII-VWF caused adhesion similar to that from normal plasma. Incubation of subendotheliurn with FVIII-VWF resulted of binding of FVIII-VWF at the surface and in subsequent perfusions a surface concentration of, FVII-VWF/cm2 was shown to correct the platelet adhesion in albumin solutions towards normal. The kinetics of binding of FVIII-VWF and platelets to the subendothelium confirm the role of bound FVIII-VWF in adhesion. Binding of FVII-VWF occurs rapidly in the first minute of perfusion to about 4 x 10-4U/cm2 and then increases further to about 10-3 u/cm2 in 5 min. Platelet adhesion is similar for perfusates with and without FVIII-WF in the first minute; then the presence of FVIII-VWF results in a two-fold increase of adhesion at 5 min. Reduced adhesion was found with the high-molecular weight component of FVIII-VWF obtained by high iconic strength dissociation. Also, the activity of glycin precipitated FVIII-VWF (e.g. Hemofil FVIII-concentrate) is impaired, cross-electrophoresis of FVIII-VWF from cryoprecipitate and FVIII-VWF after glycin precipitation showed an increased mobility or the latter, indicating a reduced molecular siie. From these experiments we conclude tnat platelet adhesion is mediated by subendothelium-bound FVIII-WWF. The degree of adhesion may depend on the molecular weight of the FVIII-VWF.

Regulation of the Synthesis of Ribulose-l,5-bisphosphate Carboxylase and Its Subunits in the Flagellate Chlorogonium elongatum. II. Coordinated Synthesis of the Large and Small Subunits

1981 ◽  
Vol 36 (11-12) ◽  
pp. 942-950 ◽  
Author(s):  
Peter Westhoff ◽  
Kurt Zimmermann ◽  
Frank Boege ◽  
Klaus Zetsche
Keyword(s):  
Rna Synthesis ◽  
De Novo ◽  
Fold Increase ◽  
Growth Conditions ◽  
Autotrophic Growth ◽  
De Novo Synthesis ◽  
Bisphosphate Carboxylase ◽  
Unicellular Green Alga ◽  
Protein And Rna Synthesis ◽  
Ribulosebisphosphate Carboxylase

Abstract Transfer of heterotrophically grown cells of the unicellular green alga Chlorogonium elongatum to autotrophic growth conditions causes a 10 -15 fold increase in the amount of the chloroplastic enzyme ribulose-1,5-bisphosphate carboxylase. This increase was found to be due to de novo synthesis. The relative proportions of large and small subunits of the enzyme do not change. Their ratio is close to 3.4, the proportions in weight of the two subunits in the holoenzyme. Continous labelling with [35S]sulfate reveals that the ratios of incorporation into large and small subunits are essentially the same in autotrophic and heterotrophic cells. Pulse-chase experiments show that the subunits are degraded synchronously. The coordinated subunit synthesis cannot be uncoupled using inhibitors of protein and RNA synthesis or high temperature of cultivation of the alga. The results suggests a very tightly coordinated synthesis of the large and small subunits of ribulosebisphosphate carboxylase.

scholarly journals The Saccharomyces cerevisiae ICL2 Gene Encodes a Mitochondrial 2-Methylisocitrate Lyase Involved in Propionyl-Coenzyme A Metabolism

2000 ◽  
Vol 182 (24) ◽  
pp. 7007-7013 ◽  
Author(s):  
Marijke A. H. Luttik ◽  
Peter Kötter ◽  
Florian A. Salomons ◽  
Ida J. van der Klei ◽  
Johannes P. van Dijken ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nitrogen Source ◽  
Coenzyme A ◽  
Isocitrate Lyase ◽  
Significant Activity ◽  
Mrna Levels ◽  
Wild Type ◽  
Cell Extracts ◽  
Lyase Activity ◽  
Null Mutants

ABSTRACT The Saccharomyces cerevisiae ICL1 gene encodes isocitrate lyase, an essential enzyme for growth on ethanol and acetate. Previous studies have demonstrated that the highly homologousICL2 gene (YPR006c) is transcribed during the growth of wild-type cells on ethanol. However, even when multiple copies are introduced, ICL2 cannot complement the growth defect oficl1 null mutants. It has therefore been suggested thatICL2 encodes a nonsense mRNA or nonfunctional protein. In the methylcitrate cycle of propionyl-coenzyme A metabolism, 2-methylisocitrate is converted to succinate and pyruvate, a reaction similar to that catalyzed by isocitrate lyase. To investigate whetherICL2 encodes a specific 2-methylisocitrate lyase, isocitrate lyase and 2-methylisocitrate lyase activities were assayed in cell extracts of wild-type S. cerevisiae and of isogenicicl1, icl2, and icl1 icl2 null mutants. Isocitrate lyase activity was absent in icl1 andicl1 icl2 null mutants, whereas in contrast, 2-methylisocitrate lyase activity was detected in the wild type and single icl mutants but not in the icl1 icl2mutant. This demonstrated that ICL2 encodes a specific 2-methylisocitrate lyase and that the ICL1-encoded isocitrate lyase exhibits a low but significant activity with 2-methylisocitrate. Subcellular fractionation studies and experiments with an ICL2-green fluorescent protein fusion demonstrated that theICL2-encoded 2-methylisocitrate lyase is located in the mitochondrial matrix. Similar to that of ICL1, transcription of ICL2 is subject to glucose catabolite repression. In glucose-limited cultures, growth with threonine as a nitrogen source resulted in a ca. threefold induction ofICL2 mRNA levels and of 2-methylisocitrate lyase activity in cell extracts relative to cultures grown with ammonia as the nitrogen source. This is consistent with an involvement of the 2-methylcitrate cycle in threonine catabolism.

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