The Regulation of Glucose-6-phosphate Dehydrogenase in Chloroplasts

1975 ◽  
Vol 30 (11-12) ◽  
pp. 756-760 ◽  
Author(s):  
Günter Wildner
Keyword(s):  
Enzyme Activity ◽  
Inhibitory Effect ◽  
Metabolic Demand ◽  
Membrane Bound ◽  
High Reduction ◽  
Reduction Charge ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Effect Of Light ◽  
Reducing Equivalents

Abstract Glucose-6-phosphate Dehydrogenase, Reduction Charge, Pentosephosphate Cycle, Chloroplasts Glucose-6-phosphate dehydrogenase from intact pea chloroplasts is partially membrane bound and inactivated upon illumination. The inhibitory effect of light can be abolished by addition of methylviologen. Kinetic experiments with glucose-6-phosphate dehydrogenase reveal that, in the dark, the enzyme activity is strongly inhibited by the accumulation of NADPH. The inhibition of NADPH can be reversed by the addition of excess NADP+ . The non-Michaelis-Menten-type kinetics suggest that the enzyme is stringently regulated by the ratio of NADPH to NADP+ plus NADPH, i. e., the “reduction charge”. These observations seem to indicate that in the light the inhibition of glucose-6-phosphate dehydrogenase is due to a high reduction charge, whereas in the dark the enzyme is controlled by the metabolic demand for reducing equivalents.

Paradoxical effect of perchlorate on thyroidal weight, glucose 6-phosphate dehydrogenase and polyamines in methylthiouracil-treated rats

1981 ◽  
Vol 97 (4) ◽  
pp. 491-495 ◽  
Author(s):  
S. Matsuzaki ◽  
M. Suzuki
Keyword(s):  
Enzyme Activity ◽  
Control Level ◽  
Sodium Perchlorate ◽  
Inhibitory Effect ◽  
Paradoxical Effect ◽  
G6pdh Activity ◽  
Wet Weight ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract. The effect of sodium perchlorate (NaClO4) on the methylthiouracil-induced increase in the activity of thyroid glucose 6-phosphate dehydrogenase (G6PDH), ornithine decarboxylase (ODC) and polyamine contents was studied in the rat. The G6PDH activity was increased nearly three-fold by methylthiouracil (MTU) but not by ClO4- at 7 days of treatment. Perchlorate lowered the MTU-induced enzyme activity to nearly the control level, without changing circulating thyrotrophin (TSH). The anion had no inhibitory effect on G6PDH activity in vitro. The possibility that an inhibitor specific for G6PDH was generated in ClO4- treated rat thyroids was excluded. The activity of ODC was greatly increased by both ClO4- and MTU, the increase being significant as early as on the second day of treatment. Perchlorate had no inhibitory effect on MTU-induced ODC activity in vivo but decreased total contents of spermidine and spermine in the thyroid, without affecting the concentration (nmoles/ g wet weight) of the polyamines. These results suggest that ClO4- acts directly on the thyroid to suppress specifically the stimulatory effect of TSH on G6PDH activity and possibly on polyamine accumulation.

Exterior and Interior Events in Early Stage of Thrombin-induced Platelet Aggregation

1977 ◽  
Vol 38 (03) ◽  
pp. 0630-0639 ◽  
Author(s):  
Shuichi Hashimoto ◽  
Sachiko Shibata ◽  
Bonro Kobayashi
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Plasma Membrane ◽  
Platelet Aggregation ◽  
Early Stage ◽  
Adenyl Cyclase ◽  
Cellular Component ◽  
Primary Event ◽  
Rabbit Platelets ◽  
Membrane Bound

SummaryTreatment of washed rabbit platelets with 1 u/ml of thrombin at 37° C resulted in a disappearance from platelets of a protein with 250,000 dalton molecular weight which was shown to be originated from plasma membrane. Parallel loss of adenyl cyclase was noted, and both reactions were complete within 30 sec. From the patterns of disc electrophoretograms, the importance of quick suppression of thrombin action in demonstrating the primary event was stressed.Thrombin induced an apparent activation of membrane bound phosphodiesterase. This reaction was also complete within 30 sec. The cellular component which contained the enzyme activity was distinct from plasma membrane. Soluble phosphodiesterase was not influenced by thrombin at all.These reactions required intact platelet cells to react with thrombin, and no reaction was detected when subcellular preparations were treated with thrombin.Possibility of collaboration of changes in externally located synthetic enzyme with those in internally located degrading enzyme in the early phase of thrombin action on platelets was suggested.

Prevalence of Listeria species in raw milk, ice cream and yogurt and effect of selected natural herbal extract on its survival

2020 ◽  
Vol 21 (3) ◽  
pp. 99-106
Author(s):  
Mona Yousef ◽  
Hazem Ramadan ◽  
Maha Al-Ashmawy
Keyword(s):  
Plant Extract ◽  
Reduction Rate ◽  
Ice Cream ◽  
Raw Milk ◽  
Inhibitory Effect ◽  
Food Preservation ◽  
Herbal Extract ◽  
Listeria Species ◽  
Soft Cheese ◽  
High Reduction

Objective: This study aimed to detect the prevalence of Listeria species in raw milk, ice cream and yogurt, and to evaluate the effect of extract of clove, thyme and pomegranate peel on such organism. Design: Descriptive study. Procedures: One hundred and fifty samples of milk, ice cream and yogurt were examined for isolation, identification and molecular identification of Listeria spp. Extraction of natural plant extract as clove, thyme and pomegranate peels and detection of their inhibitory effect on Listeria spp. Results: The prevalence of Listeria spp. in milk was 36% where 14% as L. monocytogenes, 6% L. innocua and 16% and other Listeria spp. was 16%. In yogurt, Listeria spp. was 6% as L. innocua was 2% and other Listeria spp. was 4%, while no L. monocytogenes was detected. In ice cream, Listeria spp. was 8% where L. monocytogenes was 2% and other Listeria spp. was 6% while no L. innocua was detected. The concentration of plant extract was 2.5% which showed high reduction rate on L. innocua and L. monocytogenes during shelf life of soft cheese. Conclusion and clinical relevance: Listeria is widely isolated from milk than from ice cream and yogurt. Plant extracts play role in food preservation and consider as a natural antimicrobial agent where most effective one was clove extract.

scholarly journals DOSAGE COMPENSATION IN DROSOPHILA MELANOGASTER TRIPLOIDS. II. GLUCOSE-6-PHOSPHATE DEHYDROGENASE ACTIVITY

Genetics ◽  
1973 ◽  
Vol 74 (2) ◽  
pp. 331-342
Author(s):  
Gustavo Maroni ◽  
Walter Plaut
Keyword(s):  
Enzyme Activity ◽  
Dosage Compensation ◽  
Live Weight ◽  
Regulatory Mechanisms ◽  
Special Device ◽  
Regulatory Factor ◽  
X Chromosomes ◽  
Integral Number ◽  
Level Of Activity ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACT The level of activity of the enzyme glucose-6-phosphate dehydrogenase was determinel in flies having seven different chromosomic constitutions. All those having an integral number of chromosomes [XAA, XXAA, XAAA, XXAAA, and XXXAAA (X=X chromosome, A=set of autosomes)] were found to have similar units of enzyme activity/mg live weight, while diploid females with a duplication and triploid females with a deficiency showed dosage effect. The amount of enzyme activity per cell, on the other hand, is also independent of the number of X's present but appears roughly proportional to the number of sets of autosomes.—It is proposed that dosage-compensated sex-linked genes are controlled by a positively acting regulatory factor(s) of autosomal origin. With this hypothesis it is possible to explain dosage compensation as a consequence of general regulatory mechanisms without invoking a special device which applies only to the X chromosomes.

Sinapine Esterase I. Characterization of Sinapine Esterase from Cotyledons of Raphanus sativus

1979 ◽  
Vol 34 (9-10) ◽  
pp. 715-720 ◽  
Author(s):  
Gerhild Nurmann ◽  
Dieter Strack
Keyword(s):  
Enzyme Activity ◽  
Esterase Activity ◽  
Raphanus Sativus ◽  
Sinapic Acid ◽  
Inhibitory Effect ◽  
Ph Optimum ◽  
Diisopropyl Fluorophosphate ◽  
E 600 ◽  
Red Radish

Abstract From cotyledons of Raphanus sativus (red radish) an esterase activity which catalyzes the hy­drolysis of sinapine into sinapic acid and choline has been isolated. The enzyme, which has a near absolute specificity, is not analogous with any esterase described in the literature. The reaction has a pH optimum of 8.5 and the apparent Km is 1.95 × 10-5 m. The enzyme is relatively insensi­tive to both physostigmine (eserine) {Ki = 1.73 × 10-4 m) and neostigmine (Ki = 2 .1 3 × 10-4 ᴍ). Diisopropyl fluorophosphate (DFP) showed no inhibition and diethyl p-nitrophenylphosphate (E 600) only a slight inhibitory effect at 10-5 ᴍ, respectively. Choline (10-2 ᴍ) was inhibitory but acetylcholine (10-2 ᴍ) stimulated the enzyme activity.

CYCLISCHE SCHWANKUNGEN DER AKTIVITÄTEN VON HYDROXYSTEROID-DEHYDROGENASEN IM CORPUS LUTEUM DES RINDES

1972 ◽  
Vol 69 (2) ◽  
pp. 369-384
Author(s):  
H. Brandau ◽  
L. Brandau ◽  
G. Mutzke
Keyword(s):  
Enzyme Activity ◽  
Corpus Luteum ◽  
Enzyme Activities ◽  
Optical Method ◽  
Activity Patterns ◽  
Hydroxysteroid Dehydrogenase ◽  
Corpora Lutea ◽  
Bovine Corpus Luteum ◽  
Glucose 6 Phosphate Dehydrogenase

ABSTRACT In the bovine corpora lutea periodical activities of the Δ53β-, 3β-, 17β-and 20β-hydroxysteroid dehydrogenase (OHSDH) as well as activities of glyceraldehyde-3-phosphate- and glucose-6-phosphate dehydrogenase were measured quantitatively and the alterations throughout the different stages of the cycle were studied. After homogenization of the tissue and fractionate centrifugation the enzyme activities were determined by a standardized optical method. The activities of the Δ53β-, and 3β- and 17β-OHSDH increase slowly during the first 7 days of the cycle, the maximum is reached abruptly on the 12th to 13th day of the cycle. After a striking reduction the activities decline continually to the 19th to 21st day reaching the values detected at the beginning of the cycle. The 20β-OHSDH increases slowly to the maximum on the 15th day of the cycle. Activities of the 3α-OHSDH were obtained only inconsistently. The behaviour of the activities of G6PDH was nearly identical with that of the 3β-OHSDH, while the GAPDH shows only little fluctuations of its activities. The obtained enzyme activity patterns of the maturating and high functional corpus luteum correspond to the well-known data of the biosynthetic function of the bovine corpus luteum. The changes of the amounts of progesterone and 20β-progesterol agree with the course of the activities of the 3β- resp. 20β-OHSDH.

Use of a reversed-phase evaporation vesicle formulation for a homogeneous liposome immunoassay.

1986 ◽  
Vol 32 (9) ◽  
pp. 1687-1691 ◽  
Author(s):  
E Canova-Davis ◽  
C T Redemann ◽  
Y P Vollmer ◽  
V T Kung
Keyword(s):  
Enzyme Activity ◽  
Colorimetric Detection ◽  
Reversed Phase ◽  
Homogeneous Immunoassay ◽  
Bacterial Enzyme ◽  
Liposome Preparation ◽  
Enzyme Molecules ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Relevant Range ◽  
Serum Components

Abstract Complement-mediated release of enzyme molecules from reversed-phase evaporation vesicles serves as the basis of the sensitive homogeneous immunoassay reported here. We found it necessary to co-entrap the substrate glucose 6-phosphate with the bacterial enzyme glucose-6-phosphate dehydrogenase (EC 1.1.1.49) to protect enzyme activity during liposome preparation. Enzyme can be released specifically from these liposomes by incubation with antibody and complement. the enzyme is not merely available to substrate but is actually physically free of the liposomes. Inhibition of this complement-mediated lysis by theophylline is the basis for the homogeneous liposome immunoassay described. The assay results vary linearly with theophylline concentrations in plasma in the clinically relevant range, and serum components do not interfere. The reagents in the assay kit are stable for at least seven months when stored at 5 degrees C. No nontheophylline compounds reacted significantly with the antiserum used. The assay can be run in a kinetic format, with either ultraviolet or colorimetric detection.

scholarly journals G-6-PD Long Prairie: a new glucose-6-phosphate dehydrogenase mutant exhibiting normal sensitivity to inhibition by NADPH and accompanied by nonspherocytic hemolytic anemia

Blood ◽  
1977 ◽  
Vol 49 (2) ◽  
pp. 247-251 ◽  
Author(s):  
GJ Johnson ◽  
ME Kaplan ◽  
E Beutler
Keyword(s):  
Enzyme Activity ◽  
Enzymatic Activity ◽  
Alternative Mechanism ◽  
Ph Optimum ◽  
Intracellular Enzyme ◽  
Chronic Hemolysis ◽  
Increased Sensitivity ◽  
Normal Sensitivity ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Heat Instability

Abstract The enzymatic properties of a new glucose-6-phosphate dehydrogenase (G- 6-PD) variant (G-6-PD Long Prairie) were studied in a white patient with chronic nonspherocytic hemolysis. The red cells were found to have 2.3%-7.7% normal enzymatic activity. The mutant enzyme exhibited marked heat instability, an increased pH optimum, a moderately decreased Km for G-6-P, and increased utilization of 2-deoxyglucose-6-phosphate and deamino NADP. The Km for NADP and Ki for NADPH were both normal. G-6-PD Long Prairie is an interesting new G-6-PD variant that demonstrates that chronic hemolysis can be associated with modestly decreased G-6-PD activity despite normal sensitivity to inhibition by NADPH. Although increased sensitivity to inhibition by NADPH has been postulated to decrease intracellular enzyme activity, resulting in enhanced susceptibility to hemolysis in certain G-6-PD variants with only moderately decreased enzymatic activity, an alternative mechanism of hemolysis, possibly enzyme thermolability, exists in G-6-PD Long Prairie.

scholarly journals Glucose-6-phosphate dehydrogenase deficiency in the Han Chinese population: molecular characterization and genotype–phenotype association throughout an activity distribution

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ying He ◽  
Yinhui Zhang ◽  
Xionghao Chen ◽  
Qiong Wang ◽  
Lifen Ling ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
G6pd Deficiency ◽  
National Level ◽  
Gene Mutations ◽  
Single Mutation ◽  
Missense Mutations ◽  
Severe Deficiency ◽  
Compound Mutation ◽  
Normal Males ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common hereditary disorder in China. The existing prevalence and molecular epidemiology of G6PD deficiency in China were geographically limited. In this study, the spectrum of G6PD gene mutations was well characterized in a large and diverse population all over the country; and the correlation of genotype and enzyme activity phenotype was explored for the first time. The results showed that the overall prevalence of G6PD deficiency in China was 2.10% at the national level. The top six common mutations were c.1388 G>A, c.1376 G>T, c.95 A>G, c.392 G>T, c.871 G>A and c.1024 C>T, accounting for more than 90% of G6PD deficient alleles. Compound mutation patterns were frequently observed in females with severe deficiency. The distribution of G6PD activities depended on the type of mutation patterns and genders. Hemizygote, homozygote, and compound heterozygote were predominantly associated with severe G6PD deficiency, whereas heterozygotes with single mutation mainly presented moderate enzyme deficiency. A significant gap between G6PD activities in hemizygous and normal males was observed, and yet, the overall distribution of that in females carrying missense mutations was a continuum from G6PD severely deficient to normal. This is the first report of discussing the association between G6PD genetic variants in the Chinese and enzyme activity phenotypes.

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