Photoactive ATP Dependent Glutamine Synthetase from Chloroplasts of Setaria italica Beauv

1979 ◽  
Vol 34 (3-4) ◽  
pp. 210-213 ◽  
Author(s):  
S. Venkataramana ◽  
V. S. R. Das
Keyword(s):  
Enzyme Activity ◽  
Glutamine Synthetase ◽  
Setaria Italica ◽  
Specific Requirement ◽  
Inhibitory Effects ◽  
C4 Plant

Abstract Light and ATP dependent glutamine synthetase (E. C. 6.3.1.2) activity was predominantly located in the mesophyll chloroplasts of Setaria italica Beauv., a C4 plant. ATP served the kinetic requirement while ADP exerted inhibitory effects on the enzyme activity. Sucrose stimulated the enzyme activity both in the light and in the dark. The inhibitors of both the cyclic and noncyclic photophosphorylation have suppressed the enzyme activity which suggested the specific requirement for ATP.

Inhibitory Effects of Vitamin A on TCDD-induced Cytochrome P-450 1A1 Enzyme Activity and Expression

2005 ◽  
Vol 85 (1) ◽  
pp. 727-734 ◽  
Author(s):  
Yan-Mei Yang ◽  
Dong-Yang Huang ◽  
Ge-Fei Liu ◽  
Jiu-Chang Zhong ◽  
Kun Du ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Vitamin A ◽  
Inhibitory Effects ◽  
Cytochrome P 450

scholarly journals Hepatic drug-metabolizing enzyme activity in rats pretreated with (−)-emetine or (±)-2,3-dehydroemetine

1970 ◽  
Vol 117 (3) ◽  
pp. 491-498 ◽  
Author(s):  
H. H. Miller ◽  
R. K. Johnson ◽  
J. D. Donahue ◽  
W. R. Jondorf
Keyword(s):  
Enzyme Activity ◽  
Female Rats ◽  
Inhibitory Effects ◽  
Hepatic Drug ◽  
Azo Reduction ◽  
Drug Metabolizing Enzyme ◽  
Metabolizing Enzyme ◽  
Sodium Phenobarbital ◽  
Stimulation Of

1. Pretreatment of female rats with (−)-emetine or (±)-2,3-dehydroemetine (at 18μmol/kg body wt. for 24h) prolongs the hexobarbital-induced sleeping-time of the treated animals. 2. This effect is not observed on pretreating animals with other compounds closely related to (−)-emetine, such as (−)-isoemetine or (+)-O-methylpsychotrine. 3. Liver microsomal drug-metabolizing enzyme activity in vitro as measured by N-demethylation of aminopyrine and azo-reduction of Neoprontosil is inhibited in rats pretreated with (−)-emetine or with (±)-2,3-dehydroemetine. 4. These inhibitory effects on drug metabolism in vitro are not observed in corresponding experiments involving pretreatment of rats with (−)-isoemetine or (+)-O-methylpsychotrine. 5. Co-administration of emetine or 2,3-dehydroemetine and sodium phenobarbital or 1,1-dichloro-2-o-chlorophenyl-2-p-chlorophenylethane to rats abolishes or greatly diminishes the stimulation of drug-metabolizing enzyme activity in vitro usually obtained by the administration of phenobarbital or 1,1-dichloro-2-o-chlorophenyl-2-p-chlorophenylethane alone. 6. Further, in rats pretreated with sodium phenobarbital and subsequently injected with emetine or 2,3-dehydroemetine the pre-stimulated drug-metabolizing enzyme activity in vitro is diminished. 7. The inhibitory effects on drug-metabolizing enzyme activity after pretreatment with (−)-emetine or (±)-2,3-dehydroemetine do not appear to be related to NADPH generation.

Exercise interrupts ongoing glucocorticoid-induced muscle atrophy and glutamine synthetase induction

1992 ◽  
Vol 263 (6) ◽  
pp. E1157-E1163 ◽  
Author(s):  
M. T. Falduto ◽  
A. P. Young ◽  
R. C. Hickson
Keyword(s):  
Enzyme Activity ◽  
Glutamine Synthetase ◽  
Muscle Atrophy ◽  
Contractile Activity ◽  
Hormone Treatment ◽  
Quadriceps Muscle ◽  
Treadmill Running ◽  
Female Rats ◽  
Glucocorticoid Treatment ◽  
Fast Twitch

This study was undertaken to determine whether regular endurance exercise is a deterrent to a developing state of muscle atrophy from glucocorticoids and to evaluate whether the contractile activity antagonizes the hormonal actions on glutamine synthetase, alanine aminotransferase, and cytosolic aspartate aminotransferase (cAspAT). Adult female rats were administered cortisol acetate (CA, 100 mg/kg body wt) or an equal volume of the vehicle solution for up to 15 days. Exercise (treadmill running at 31 m/min, 10% grade, 90 min/day) was introduced after 4 days of CA treatment, at which time plantaris and quadriceps muscle mass had been reduced to 90% of control levels. Running for 11 consecutive days prevented 40 mg of the 90-mg loss and 227 mg of the 808-mg loss that were subsequently observed in plantaris and quadriceps muscles, respectively, in the sedentary animals. Glutamine synthetase mRNA and enzyme activity were elevated threefold by glucocorticoid treatment in the deep quadriceps (fast-twitch red) muscles after 4 days. Initiating exercise completely interfered with the further hormonal induction (to approximately 5-fold) of this enzyme and, after 11 consecutive days of the exercise regimen, glutamine synthetase mRNA and enzyme activity were 58 and 68% of values from CA-treated sedentary animals. In vehicle-treated groups, basal levels of glutamine synthetase expression were also diminished by exercise to approximately 40% of the values in sedentary controls. Hormone treatment did not alter either aminotransferase enzyme activity but reduced cAspAT mRNA in fast-twitch red muscles by 50%. Exercise abolished the glucocorticoid effect on cAspAT mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification of fat body glutathioneS‐transferase from the desert locustSchistocerca gregaria: investigation of flavonoid inhibitory effects on enzyme activity

2019 ◽  
Vol 44 (3-4) ◽  
pp. 187-199 ◽  
Author(s):  
Ragaa R. Hamed ◽  
Tahany M. Maharem ◽  
Rasha A. Guneidy ◽  
Manal A. Emam ◽  
Ghada S. A. Abdel Karim
Keyword(s):  
Enzyme Activity ◽  
Fat Body ◽  
Inhibitory Effects

Cellular concentrations of glutamine synthetase in murine organs

2006 ◽  
Vol 84 (2) ◽  
pp. 215-231 ◽  
Author(s):  
Henny W.M van Straaten ◽  
Youji He ◽  
Marjan M van Duist ◽  
Wil T Labruyère ◽  
Jacqueline L.M Vermeulen ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Epithelial Cells ◽  
Glutamine Synthetase ◽  
Posttranscriptional Regulation ◽  
Minor Importance ◽  
Activity Levels ◽  
Protein Ratio ◽  
Cellular Concentration ◽  
S3 Segment ◽  
Relative Differences

Glutamine synthetase (GS) is the only enzyme that can synthesize glutamine, but it also functions to detoxify glutamate and ammonia. Organs with high cellular concentrations of GS appear to function primarily to remove glutamate or ammonia, whereas those with a low cellular concentration appear to primarily produce glutamine. To validate this apparent dichotomy and to clarify its regulation, we determined the GS concentrations in 18 organs of the mouse. There was a >100-fold difference in GS mRNA, protein, and enzyme-activity levels among organs, whereas there was only a 20-fold difference in the GS protein:mRNA ratio, suggesting extensive transcriptional and posttranscriptional regulation. In contrast, only small differences in the GS enzyme activity : protein ratio were found, indicating that posttrans lational regulation is of minor importance. The cellular concentration of GS was determined by relating the relative differences in cellular GS concentration, detected using image analysis of immunohistochemically stained tissue sections, to the biochemical data. There was a >1000-fold difference in cellular concentrations of GS between GS-positive cells in different organs, and cellular concentrations were up to 20× higher in subpopulations of cells within organs than in whole organs. GS activity was highest in pericentral hepatocytes (~485 µmol·g–1·min–1), followed in descending order by epithelial cells in the epididymal head, Leydig cells in the testicular interstitium, epithelial cells of the uterine tube, acid-producing parietal cells in the stomach, epithelial cells of the S3 segment of the proximal convoluted tubule of the kidney, astrocytes of the central nervous tissue, and adipose tissue. GS activity in muscle amounted to only 0.4 µmol·g–1·min–1. Our findings confirmed the postulated dichotomy between cellular concentration and GS function.Key words: mRNA, protein, enzyme activity, posttranscriptional regulation, quantitative immunohistochemistry.

Inhibitory effects of commonly used herbal extracts on UGT1A1 enzyme activity

Xenobiotica ◽  
2010 ◽  
Vol 40 (10) ◽  
pp. 663-669 ◽  
Author(s):  
Mohamed-Eslam F. Mohamed ◽  
Tiffany Tseng ◽  
Reginald F. Frye
Keyword(s):  
Enzyme Activity ◽  
Herbal Extracts ◽  
Inhibitory Effects

Glutamine interferes with glucocorticoid-induced expression of glutamine synthetase in skeletal muscle

1996 ◽  
Vol 270 (5) ◽  
pp. E912-E917 ◽  
Author(s):  
R. C. Hickson ◽  
L. E. Wegrzyn ◽  
D. F. Osborne ◽  
I. E. Karl
Keyword(s):  
Skeletal Muscle ◽  
Enzyme Activity ◽  
Glutamine Synthetase ◽  
Hormone Treatment ◽  
Skeletal Muscle Atrophy ◽  
Fiber Types ◽  
Gene Encoding ◽  
Glucocorticoid Treatment ◽  
Amino Acid Infusion ◽  
Fast Twitch

Skeletal muscle atrophy from glucocorticoids is prevented by glutamine infusion. Because the gene-encoding glutamine synthetase (GS) is glucocorticoid inducible, it represented an appropriate model for resting whether glucocorticoids and glutamine exert opposing actions on the expression of specific genes related to atrophy in muscle tissue. Rats were administered hydrocortisone 21-acetate or the dosing vehicle (carboxymethyl cellulose) and were infused with saline (Sal) or glutamine (Gln, 240 mM, 0.75 ml/h) for 7 days. Hormone treatment did not significantly lower glutamine levels in fast-twitch white or red regions of the quadriceps. Despite higher serum glutamine concentrations with amino acid infusion [1.52 +/- 0.03 (Gln) vs. 1.20 +/- 0.04 (Sal) mumol/ml], muscle glutamine concentrations were not markedly increased in these fiber types. In saline-infused animals, glucocorticoid treatment produced 200-300% increases in plantaris, fast-twitch white, and fast-twitch red muscle GS enzyme activity and mRNA. Moreover, in all muscle types studied, glutamine infusion diminished glucocorticoid effects on GS enzyme activity to 131-159% and on GS mRNA to 110-200% of the values in saline-treated controls. These data demonstrate that glutamine infusion results in inhibiting GS expression, but the absence of changes in muscle glutamine concentration suggests the interplay of additional regulators of the GS gene.

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