Cellular concentrations of glutamine synthetase in murine organs

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.

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Low Psychosine in Krabbe Disease with Onset in Late Infancy: A Case Report

International Journal of Neonatal Screening ◽

10.3390/ijns7020028 ◽

2021 ◽

Vol 7 (2) ◽

pp. 28

Author(s):

Camille S. Corre ◽

Dietrich Matern ◽

Joan E. Pellegrino ◽

Carlos A. Saavedra-Matiz ◽

Joseph J. Orsini ◽

...

Keyword(s):

New York ◽

Enzyme Activity ◽

Clinical Presentation ◽

Neurodegenerative Disorder ◽

New York State ◽

Disease Onset ◽

Early Infancy ◽

Krabbe Disease ◽

Activity Levels ◽

Hematopoietic Stem

Krabbe disease (KD) is a rare inherited neurodegenerative disorder caused by a deficiency in galactocerebrosidase enzyme activity, which can present in early infancy, requiring an urgent referral for hematopoietic stem cell transplantation, or later in life. Newborn screening (NBS) for KD requires identification and risk-stratification of patients based on laboratory values to predict disease onset in early infancy or later in life. The biomarker psychosine plays a key role in NBS algorithms to ascertain probability of early-onset disease. This report describes a patient who was screened positive for KD in New York State, had a likely pathogenic genotype, and showed markedly reduced enzyme activity but surprisingly low psychosine levels. The patient ultimately developed KD in late infancy, an outcome not clearly predicted by existing NBS algorithms. It remains critical that psychosine levels be evaluated alongside genotype, enzyme activity levels, and the patient’s evolving clinical presentation, ideally in consultation with experts in KD, in order to guide diagnosis and plans for monitoring.

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Enzyme Activity Levels in Mammalian Cell Cultures

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)64718-0 ◽

1958 ◽

Vol 233 (3) ◽

pp. 634-636 ◽

Cited By ~ 3

Author(s):

Irving Lieberman ◽

Peter Ove

Keyword(s):

Enzyme Activity ◽

Mammalian Cell ◽

Cell Cultures ◽

Activity Levels ◽

Mammalian Cell Cultures

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The Molecular Basis of Quantitative Genetic Variation in Central and Secondary Metabolism in Arabidopsis

Genetics ◽

10.1093/genetics/149.2.739 ◽

1998 ◽

Vol 149 (2) ◽

pp. 739-747 ◽

Cited By ~ 7

Author(s):

Thomas Mitchell-Olds ◽

Deana Pedersen

Keyword(s):

Enzyme Activity ◽

Genetic Variation ◽

Secondary Metabolism ◽

Genetic Correlations ◽

Theoretical Models ◽

Model Systems ◽

Activity Levels ◽

Significant Qtls ◽

Cis Acting ◽

Quantitative Genetic

Abstract To find the genes controlling quantitative variation, we need model systems where functional information on physiology, development, and gene regulation can guide evolutionary inferences. We mapped quantitative trait loci (QTLs) influencing quantitative levels of enzyme activity in primary and secondary metabolism in Arabidopsis. All 10 enzymes showed highly significant quantitative genetic variation. Strong positive genetic correlations were found among activity levels of 5 glycolytic enzymes, PGI, PGM, GPD, FBP, and G6P, suggesting that enzymes with closely related metabolic functions are coregulated. Significant QTLs were found influencing activity of most enzymes. Some enzyme activity QTLs mapped very close to known enzyme-encoding loci (e.g., hexokinase, PGI, and PGM). A hexokinase QTL is attributable to cis-acting regulatory variation at the AtHXK1 locus or a closely linked regulatory locus, rather than polypeptide sequence differences. We also found a QTL on chromosome IV that may be a joint regulator of GPD, PGI, and G6P activity. In addition, a QTL affecting PGM activity maps within 700 kb of the PGM-encoding locus. This QTL is predicted to alter starch biosynthesis by 3.4%, corresponding with theoretical models, suggesting that QTLs reflect pleiotropic effects of mutant alleles.

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Rat uterine microbiochemistry: metabolic enzyme activities stimulated by 17-beta-estradiol are localized in epithelial cells.

Journal of Histochemistry & Cytochemistry ◽

10.1177/35.6.3571958 ◽

1987 ◽

Vol 35 (6) ◽

pp. 657-662 ◽

Cited By ~ 2

Author(s):

J P Holt ◽

E Rhe

Keyword(s):

Enzyme Activity ◽

Smooth Muscle ◽

Epithelial Cells ◽

Dose Response ◽

Enzyme Activities ◽

Time Course ◽

Citrate Synthase ◽

Ovariectomized Rats ◽

Similar Response ◽

Estradiol Treatment

Lactate dehydrogenase (LDH; EC 1.1.1.27), citrate synthase (CS; EC 4.1.3.7), and beta-hydroxyacyl-CoA-dehydrogenase (beta-OH-acyl-CoA-DH; EC 1.1.1.35) activities were determined in each of the three major cell types of rat uterus, i.e., epithelial, stromal, and smooth muscle, using quantitative microanalytical techniques. Adult ovariectomized rats were treated with 17-beta-estradiol to determine the time course and dose response (0.025-50 micrograms/300-g rat) effect of estrogen on enzyme activity of each type of uterine cell. The use of "oil well" and enzyme-cycling microtechniques to determine the time course and the dose responses of enzyme activity changes required microassays involving 1595 microdissected single cell specimens. Estradiol treatment increased epithelial LDH, CS and beta-OH-acyl-CoA-DH activity but had no effect on these enzymes in the stroma or in smooth muscle cells. The estradiol-stimulated peak enzyme activities on Day 4 in the intervention group are compared with those in the ovariectomized rat controls as follows: LDH, 44.5 +/- 3.5 vs 22.3 +/- 3.9; CS, 3.5 +/- 0.2 vs 1.5 +/- 0.6; beta-OH-acyl-CoA-H, 3.5 +/- 0.32 vs 2.2 +/- 0.2 (mean +/- standard deviation; mol/kg/hr). Stromal cell activities (LDH, 7.4 +/- 1.0; CS, 1.2 +/- 0.2; beta-OH-acyl-CoA-DH, 0.9 +/- 0.1) were significantly lower than epithelial cell levels and were similar to smooth muscle levels. Therefore, even in the ovariectomized animal epithelial cells have markedly higher metabolic activity compared with adjacent cells. The enzyme activities are expressed as moles of substrate reacting per kilogram of dry weight per hour. All three enzymes exhibited a 17-beta-estradiol-induced dose response between 0.025-0.15 micrograms/300-g rat. The three enzymes studied all had similar response patterns to estrogen. The effect of estradiol was restricted to epithelial cells, with enzyme activities increasing to maximal levels after approximately 96 hr of hormone treatment. This study therefore not only confirms the specific and differential metabolic responses of uterine cells to estradiol treatment, but clearly demonstrates that marked metabolic differences exist between epithelial cells and stromal or smooth muscle uterine cells.

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Corrigendum: Chloroplast Glutamine Synthetase, the Key Regulator of Nitrogen Metabolism in Wheat, Performs Its Role by Fine Regulation of Enzyme Activity via Negative Cooperativity of Its Subunits

Frontiers in Plant Science ◽

10.3389/fpls.2018.00466 ◽

2018 ◽

Vol 9 ◽

Cited By ~ 1

Author(s):

Edit Németh ◽

Zoltán Nagy ◽

Attila Pécsváradi

Keyword(s):

Enzyme Activity ◽

Glutamine Synthetase ◽

Nitrogen Metabolism ◽

Negative Cooperativity ◽

Fine Regulation ◽

Regulation Of Enzyme Activity

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HORMONAL CONTROL OF ENZYME ACTIVITY DURING THE PLASMA MEMBRANE TRANSFORMATION OF UTERINE EPITHELIAL CELLS

Cell Biology International ◽

10.1006/cbir.2001.0771 ◽

2001 ◽

Vol 25 (9) ◽

pp. 859-871 ◽

Cited By ~ 9

Author(s):

M Bucci

Keyword(s):

Enzyme Activity ◽

Plasma Membrane ◽

Epithelial Cells ◽

Hormonal Control ◽

Uterine Epithelial Cells ◽

Membrane Transformation

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Protective Effects of 3-benzoyl-7-hydroxy Coumarin on Liver of Adult Rat Exposed to Aluminium Chloride

Acta Chimica Slovenica ◽

10.17344/acsi.2020.6390 ◽

2021 ◽

Vol 68 (1) ◽

pp. 222-228

Author(s):

Ahmet Özkaya ◽

Kenan Türkan

Keyword(s):

Oxidative Stress ◽

Enzyme Activity ◽

Aluminium Chloride ◽

Control Group ◽

Albino Rats ◽

Activity Levels ◽

Protective Effects ◽

Adult Rat ◽

Antioxidant Enzyme System ◽

Hydroxy Coumarin

In this study, the effects of 3-benzoyl-7-hydroxy coumarin molecule on mineral and antioxidant enzymes were investigated in rat liver exposed to oxidative stress with aluminium chloride (AlCl3). Adult male Wistar albino rats were divided into four groups as Control, Coumarin, AlCl3, and Coumarin + AlCl3. Coumarin at the dose of 10 mg/kg and AlCl3 at the dose of 8.3 mg/kg were administered for 30 days every other day. In AlCl3 group, malondialdehyde (MDA), iron (Fe), aluminium (Al) and copper (Cu) levels increased compared to the control group, while glutathione (GSH) level, glutathione S-transferase (GST), and carboxylesterase (Ces) enzyme activity levels decreased. In Coumarin + AlCl3 group, MDA, Fe, Al and Cu levels decreased with the effect of coumarin compared to AlCl3 group, while GSH level, and GST enzyme activity levels increased. According to our results, AlCl3 generates oxidative stress in rat livers, and we believe that 3-benzoyl-7-hydroxy coumarin has an ameliorative effect on antioxidant enzyme system, Al, Fe and Cu levels.

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Impact of allicin on enzyme activity, cytokine secretion, and gene expression dynamics in oxidatively‐stressed epithelial cells (1045.19)

The FASEB Journal ◽

10.1096/fasebj.28.1_supplement.1045.19 ◽

2014 ◽

Vol 28 (S1) ◽

Author(s):

Nathan Horn ◽

Kolapo Ajuwon ◽

Guy Miller ◽

Olayiwola Adeola

Keyword(s):

Gene Expression ◽

Enzyme Activity ◽

Epithelial Cells ◽

Cytokine Secretion ◽

Gene Expression Dynamics

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Differential effects of non-ionic detergents on microsomal and sarcolemmal adenylate cyclase in cardiac muscle

Biochemical Journal ◽

10.1042/bj1750171 ◽

1978 ◽

Vol 175 (1) ◽

pp. 171-180 ◽

Cited By ~ 23

Author(s):

Prakash V. Sulakhe ◽

Njanoor Narayanan

Keyword(s):

Enzyme Activity ◽

Sarcoplasmic Reticulum ◽

Adenylate Cyclase ◽

Cyclase Activity ◽

Adenylate Cyclase Activity ◽

Protein Ratio ◽

Guinea Pig Heart ◽

Cardiac Sarcoplasmic Reticulum ◽

Ionic Detergent ◽

Triton X

1. About 4 and 23% of the homogenate adenylate cyclase activity was recovered in the microsomal and sarcolemmal fractions isolated from guinea-pig heart ventricles. 2. Cardiac microsomal adenylate cyclase activity [basal as well as p[NH]ppG (guanyl-5′-yl imidodiphosphate)- and NaF-stimulated] was increased over 2-fold in the presence of Lubrol-PX (0.01–0.1%). 3. The sarcolemmal enzyme, however, showed concentration-dependent inhibition caused by the detergent under all assay conditions, except when p[NH]ppG was included in the assay. In the latter case, the detergent (0.01–0.02%) caused a modest increase (30–45%) in enzyme activity. 4. Another non-ionic detergent, Triton X-100, also stimulated the microsomal cyclase and inhibited the sarcolemmal enzyme. 5. With either membrane fraction, Lubrol-PX solubilized the enzyme when the detergent/membrane protein ratio was 2.5 (μmol of detergent/mg of protein). 6. The findings with homogenate and a washed particulate fraction resembled those obtained with sarcolemma, and those with isolated sarcoplasmic reticulum resembled those with microsomal preparations. 7. p[NH]ppG, and to some extent NaF, protected the detergent-induced inactivation of the enzyme observed at higher detergent concentrations (0.5% Lubrol-PX and 0.05–0.5% Triton X-100). 8. In the absence of detergents, p[NH]ppG increased the basal enzyme activity about 2-fold in microsomal fractions, but did not appreciably stimulate the sarcolemmal enzyme. Isoproterenol, on the other hand, increased the sarcolemmal enzyme activity (>2-fold) in the presence of p[NH]ppG and caused only moderate stimulation (31%) of the microsomal enzyme under these conditions. 9. These findings support the view that, although the bulk of adenylate cyclase resides in heart sarcolemma (plasma membrane), the microsomal activity cannot be accounted for solely by contamination of the microsomal fraction with sarcolemma, as has been suggested by others [Besch, Jones & Watanabe (1976) Circ. Res.39, 586–595; Engelhard, Plut & Storm (1976) Biochim. Biophys. Acta451, 48–61]. Further, the results of this study show that cardiac sarcoplasmic-reticulum membranes possess this enzyme.

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