Differential Regulation of Two Genes Controlling the Biosynthesis of Isovitexin 7-O-Galactoside in Silene Plants

1986 ◽  
Vol 41 (1-2) ◽  
pp. 9-17 ◽  
Author(s):  
Jan M. Steyns
Keyword(s):  
Enzyme Activity ◽  
Kinetic Parameters ◽  
Enzyme Activities ◽  
Differential Regulation ◽  
Heat Inactivation ◽  
Enzyme Kinetic ◽  
Ph Optimum ◽  
Galactosyl Transferase ◽  
Acceptor Specificity ◽  
Ontogenetic Stages

Abstract The expression of the allelic isovitexin 7-O-glycosylation genes gG (transfer of glucose) and gX (transfer of xylose) was studied in cotyledons, rosette leaves, stem leaves and petals of Silene plants. These studies revealed that gG is expressed in all ontogenetic stages, whereas its allele gX is only expressed in the petals. In the vegetative parts of gX individuals 7-O -xylosylation is replaced by 7-O-galactosylation. The possibility that gX encodes an enzyme activity that catalyzes different reactions in the petals and the vegetative parts resulting in the accumulation of the 7-O-xyloside and the 7-O-galactoside respectively, has been disproved. It is shown that there are two different enzymes catalyzing the biosynthesis of isovitexin 7-O-galactoside. These 7-O -galactosyl-transferase activities differ with respect to heat inactivation, pH optimum , flavone acceptor specificity and Michaelis-Menten enzyme kinetic parameters. The genes controlling these enzyme activities are regulated differentially, with gene O7g (described previously by Steyns et al. [11]), expressed in the cotyledons and the rosette leaves and Xgal in the stem leaves and petals.

scholarly journals Increase in alkaline phosphatase activity in calvaria cells cultured with diphosphonates

1979 ◽  
Vol 183 (1) ◽  
pp. 73-81 ◽  
Author(s):  
R Felix ◽  
H Fleisch
Keyword(s):  
Alkaline Phosphatase ◽  
Protein Synthesis ◽  
Enzyme Activity ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Heat Inactivation ◽  
High Concentration ◽  
Control Value ◽  
Km Value ◽  
Inhibitor Of Protein Synthesis

1. Dichloromethanediphosphonate and to a lesser degree 1-hydroxyethane-1,1-diphosphonate, two compounds characterized by a P-C-P bond, increased the alkaline phosphatase activity of cultured rat calvaria cells up to 30 times in a dose-dependent fashion. 2. Both diphosphonates also slightly inhibited the protein synthesis in these cells. 3. Thymidine, an inhibitor of cell division, did not inhibit the induction of the enzyme, indicating that the increase in enzyme activity was not due to the formation of a specific population of cells with high alkaline phosphatase activity. 4. The effect on alkaline phosphatase was suppressed by the addition of cycloheximide, an inhibitor of protein synthesis. 5. After subculturing the stimulated cells in medium without diphosphonates, the enzyme activity fell almost to the control value. 6. Bovine parathyrin diminished the enzyme activity of the control cells and the cells treated with dichloromethanediphosphonate; however, at high concentration the effect of parathyrin was greater on the diphosphonate-treated cells than on the control cells. 7. The electrophoretic behaviour, heat inactivation, inhibition by bromotetramisole or by phenylalanine, and the Km value of the induced enzyme were identical with that of the control enzyme.

Analytical method for the estimation of enzyme kinetic parameters

1969 ◽  
Vol 191 (1) ◽  
pp. 155-157 ◽  
Author(s):  
A.P. Brestkin ◽  
E.V. Rozengart ◽  
V.A. Samokish ◽  
I.N. Soboleva
Keyword(s):  
Kinetic Parameters ◽  
Analytical Method ◽  
Enzyme Kinetic

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

1987 ◽  
Vol 35 (6) ◽  
pp. 657-662 ◽  
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.

Change Analysis of Enzyme Activity under Different Conditions of Film Remnant in Soil

2012 ◽  
Vol 518-523 ◽  
pp. 39-43
Author(s):  
Xiao Guang Zhao ◽  
Yuan Yuan Guan ◽  
Wen Yu Huang
Keyword(s):  
Enzyme Activity ◽  
Enzyme Activities ◽  
Scientific Basis ◽  
Soil Enzyme ◽  
Soil Microorganism ◽  
Soil Enzyme Activities ◽  
Change Analysis ◽  
Soil Material ◽  
The Relationship

In this paper, simulated experiments were performed in pots by using soil materials in different conditions of film remnant. Based on the research on soil microorganism quantity trends of soil enzyme activities were analyzed systematically: soil without film remnant, soil with film remnant for 5, 10, 15 and 20 years. By analyzing crop progress, the relationship with soil material was studied, in order to provide scientific basis for the variation laws between different conditions of film remnant and the activity of soil enzyme.

scholarly journals Interaction of soluble glucosyl- and mannosyl-transferase enzyme activities in the synthesis of a glucomannan

1972 ◽  
Vol 129 (3) ◽  
pp. 645-655 ◽  
Author(s):  
J. S. Heller ◽  
C. L. Villemez
Keyword(s):  
Enzyme Activity ◽  
Enzyme Activities ◽  
Enzyme Preparation ◽  
The Other ◽  
Acceptor Molecule ◽  
Soluble Enzyme ◽  
Phaseolus Aureus ◽  
Polymeric Product ◽  
Sugar Nucleotide ◽  
Solubilized Enzyme

A neutral-detergent-solubilized-enzyme preparation derived from Phaseolus aureus hypocotyls contains two types of glycosyltransferase activity. One, mannosyltransferase enzyme activity, utilizes GDP-α-d-mannose as the sugar nucleotide substrate. The other, glucosyltransferase enzyme activity, utilizes GDP-α-d-glucose as the sugar nucleotide substrate. The soluble enzyme preparation catalyses the formation of what appears to be a homopolysaccharide when either sugar nucleotide is the only substrate present. A β-(1→4)-linked mannan is the only polymeric product when only GDP-α-d-mannose is added. A β-(1→4)-linked glucan is the only polymeric product when only GDP-α-d-glucose is added. In the presence of both sugar nucleotides, however, a β-(1→4)-linked glucomannan is formed. There are indications that endogenous sugar donors may be present in the enzyme preparation. There appear to be only two glycosyltransferases in the enzyme preparation, each catalysing the transfer of a different sugar to the same type of acceptor molecule. The glucosyltransferase requires the continual production of mannose-containing acceptor molecules for maintenance of enzyme activity, and is thereby dependent upon the activity of the mannosyltransferase. The mannosyltransferase, on the other hand, does not require the continual production of glucose-containing acceptors for maintenance of enzyme activity, but is severely inhibited by GDP-α-P-glucose. These properties promote the synthesis of β-(1→4)-linked glucomannan rather than β-(1→4)-linked glucan plus β-(1→4)-linked mannan when both sugar nucleotide substrates are present.

Estimation of kinetic parameters of androgen-synthesizing enzyme activities in superfused Leydig cells from rat testes: Difference between endogenous and exogenous substrates

1984 ◽  
Vol 4 (6) ◽  
pp. 483-488 ◽  
Author(s):  
Nikolaus Kühn-Velten ◽  
Joachim Wolff ◽  
Wolfgang Staib
Keyword(s):  
Steady State ◽  
Kinetic Parameters ◽  
Active Site ◽  
Enzyme Activities ◽  
Substrate Concentration ◽  
Leydig Cells ◽  
Hydroxysteroid Dehydrogenase ◽  
Endogenous Substrate ◽  
Catalyzed Reactions ◽  
Actual Substrate

Kinetic parameters of 3β-hydroxysteroid dehydrogenase/isomerase, steroid-17α-monooxygenase, and steroid-17,20-lyase activities were estimated under steady-state conditions. Purified Leydig cells from rat testes were superfused with pregnenolone, progesterone, or 17α-hydroxyprogesterone. The Km values for both the monooxygenase- and the lyase-catalyzed reactions were by factors of five to ten higher if analyzed with the exogenously added substrate (0.98 and 0.65 μM, respectively) than if calculated from endogenous substrate derived from a precursor (0.10 and 0.13 μM, respectively). This discrepancy may be explained by different substrate partition between the intra- and extraceIJular spaces and by different substrate concentration at the active site of the respective enzyme, depending on whether the actual substrate is of exogenous or endogenous source.

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.

scholarly journals Research Progress of Sirtuin4 in Cancer

2021 ◽  
Vol 10 ◽  
Author(s):  
Yibing Bai ◽  
Jiani Yang ◽  
Ying Cui ◽  
Yuanfei Yao ◽  
Feng Wu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Enzyme Activity ◽  
Energy Metabolism ◽  
Nicotinamide Adenine Dinucleotide ◽  
Enzyme Activities ◽  
Research Progress ◽  
Diverse Range ◽  
Catalytic Activities ◽  
Cellular Processes ◽  
Dependent Protein

Sirtuins (SIRTs) are members of the silent information regulator-2 family. They are a conserved family of nicotinamide adenine dinucleotide-dependent protein lysine deacylases. SIRTS are involved in intricate cellular processes. There are seven subtypes of SIRTs (1–7) in mammals. SIRT4 is located mainly in mitochondria and has various catalytic activities. These enzyme activities give it a diverse range of important biologic functions, such as energy metabolism, oxidative stress, and aging. Cancer is characterized as reprogramming of energy metabolism and redox imbalance, and SIRT4 can affect tumorigenesis. Here, we review the structure, localization, and enzyme activity of SIRT4 and its role in various neoplasms.

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