Biosynthesis Of Gallotannins. ß-Glucogallin-Dependent Galloylation Of 1,6-Digailoylglucose To 1,2,6-Trigalloylglucose

1991 ◽  
Vol 46 (5-6) ◽  
pp. 389-394 ◽  
Author(s):  
Georg G. Gross ◽  
Klaus Denzel
Keyword(s):  
Molecular Weight ◽  
Enzymatic Reaction ◽  
Relative Activity ◽  
The Other ◽  
Ph Optimum ◽  
Acceptor Substrate ◽  
Free Glucose ◽  
Rhus Typhina ◽  
Acyl Donors ◽  
Stimulation Of

An enzyme from leaves of sumach (Rhus typhina) was partially purified that catalyzes the β-glucogallin (l-O-galloylglucose)-dependent galloylation of 1,6-digalloylglucose, thus forming 1,2,6-trigalloylglucose and free glucose. This acyltransferase had a molecular weight of ca. 750,000 and a pH optimum at 5.0-5 .5. Besides β-glucogallin (Km = 3.9 mM ) , also related 1-O-phenylcarboxylglucoses acted as acyl donors. On the other hand, the acceptor substrate, 1,6-digalloylglucose (Km = 0.9 mM ) , could only be replaced by 1,6-diprotocatechuoylglucose (relative activity 46%); however, also tri-, tetra-, and pentagalloylglucoses were galloylated. A pronounced stimulation of the enzymatic reaction was observed upon addition of penta- or hexagalloylglucose into the assay mixtures. The systematic name “ β-glucogallin: 1,6-di-O-galloylglucose 2-O-galloyltransferase” (EC 2.3.1. - ) is proposed for the enzyme

Studies on Partially Purified Pig Liver Steroid Δ4-5β-Reductase Activity

1973 ◽  
Vol 51 (12) ◽  
pp. 1661-1668 ◽  
Author(s):  
Edward J. Van Doorn ◽  
John C. Nduaguba ◽  
Albert F. Clark
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Enzyme Preparation ◽  
Reductase Activity ◽  
Enzymatic Reaction ◽  
Ph Optimum ◽  
Pig Liver ◽  
Liver Cytosol ◽  
End Products ◽  
Tris Maleate

Some properties of partially purified steroid Δ4-5β-reductase activity of pig liver cytosol have been studied using testosterone as substrate. The enzymatic activity was stable for 72 h at 4° when stored in 0.05 M Tris–maleate buffer, pH 7.4 or 8.4; storage at pH 8 at 4° resulted in a 25% decrease in activity in 30 days. The pH optimum in Tris–maleate buffers was 6.4. Enzyme activity was completely inhibited by 0.2 mM p-chloromercuribenzenesulfonate and 0.2 mM p-chloromercuribenzoate. Enzyme activity was reduced by 20% and 45% with 1.0 mM iodoacetamide and 1.0 mM N-ethylmaleimide, respectively. The end products of the enzymatic reaction, NADP+ and 5β-dihydrotestosterone, inhibited the rate of reduction of testosterone. Testosterone Δ4-5β-reductase activity was present in protein of molecular weight 25 000–30 000, as determined by gel filtration.The enzyme preparation reduced a variety of C19 and C21 steroids. The highest activity (twice that for testosterone) was found with aldosterone as substrate.

Properties and characteristics of partly purified glutamate dehydrogenase from sheep rumen mucosa

1981 ◽  
Vol 46 (11) ◽  
pp. 2766-2773
Author(s):  
Katarína Holovská ◽  
Viera Lenártová ◽  
Ivan Havassy
Keyword(s):  
Molecular Weight ◽  
Glutamate Dehydrogenase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Enzymatic Reaction ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Ph Optimum ◽  
Relative Molecular Weight ◽  
Sheep Rumen ◽  
The Individual

The purification of glutamate dehydrogenase from sheep rumen mucosa on DEAE-cellulose afforded two enzyme fractions with glutamate dehydrogenase activity. The enzyme fraction II (tissue glutamate dehydrogenase) was freed of contaminating proteins in the subsequent purification step on Sephadex G-200. The approximate relative molecular weight (260 000) of tissue glutamate dehydrogenase (fraction II) was determined by gel filtration on Sephadex G-200 and the approximate relative molecular weight of its polypeptide chain (48 000) was established by polyacrylamide gel electrophoresis in SDS. The pH-optimum of fraction II was 7.9. The effect of substrate concentration on the rate of the enzymatic reaction was examined and the following apparent Michaelis' constants were found for the individual substrates: NADH 6.25 . 10-5 mol/l, 2-oxoglutarate 4.5 . 10-3 mol/l, and NH4+ 77 . 10-3 mol/l.

scholarly journals The isocitrate dehydrogenases of Acinetobacter lwoffi. Studies on the regulation of nicotinamide–adenine dinucleotide phosphate-linked isoenzyme

1973 ◽  
Vol 132 (2) ◽  
pp. 215-221 ◽  
Author(s):  
Colin H. Self ◽  
Malcolm G. Parker ◽  
P. David J. Weitzman
Keyword(s):  
Molecular Weight ◽  
Nicotinamide Adenine Dinucleotide ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Nicotinamide Adenine ◽  
Ph Optimum ◽  
Low Concentrations ◽  
Molecular Weight Form ◽  
Metabolic Significance ◽  
Regulatory Sites ◽  
Stimulation Of

Of the two NADP-linked isocitrate dehydrogenases in Acinetobacter lwoffi the higher-molecular-weight form, isoenzyme-II, is reversibly stimulated sixfold by low concentrations of glyoxylate or pyruvate. Kinetic results indicate that this stimulation of activity involves both an increase in Vmax. and a decrease in the apparent Km values for substrates, most markedly that for NADP+. Other changes brought about by glyoxylate or pyruvate include a shift in the pH optimum for activity and an increased stability to inactivation by heat or urea. Mixtures of glyoxylate plus oxaloacetate, known to inhibit isocitrate dehydrogenases from other organisms, produce inhibition of both A. lowffi isoenzymes, and do not reflect the stimulatory specificity of glyoxylate for isoenzyme-II. Isoenzyme-II is also stimulated by AMP and ADP, but the activation by glyoxylate or pyruvate is shown to be quite independent of the adenylate activation. Differential desensitization of the enzyme by urea to the two types of activator further supports the view that the enzyme possesses two distinct allosteric regulatory sites. The metabolic significance of the activations is discussed.

scholarly journals Sensations from a single M-cone depend on the activity of surrounding S-cones

2018 ◽  
Author(s):  
Brian P. Schmidt ◽  
Ramkumar Sabesan ◽  
William S. Tuten ◽  
Jay Neitz ◽  
Austin Roorda
Keyword(s):  
Adaptive Optics ◽  
Relative Activity ◽  
The Other ◽  
White Background ◽  
Coarse Scale ◽  
Retinal Position ◽  
Natural Movement ◽  
Short Wavelength Light ◽  
Wavelength Light ◽  
Stimulation Of

ABSTRACTColor vision requires the activity of cone photoreceptors to be compared in post-receptoral circuitry. Decades of psychophysical measurements have quantified the nature of these comparative interactions on a coarse scale. How such findings generalize to a cellular scale remains unclear. To answer that question, we quantified the influence of surrounding light on the appearance of spots targeted to individual cones. The eye’s aberrations were corrected with adaptive optics and retinal position was precisely tracked in real-time to compensate for natural movement. Subjects reported the color appearance of each spot. A majority of L-and M-cones consistently gave rise to the sensation of white, while a smaller group repeatedly elicited hue sensations. When blue sensations were reported they were more likely mediated by M- than L-cones. Blue sensations were elicited from M-cones against a short-wavelength light that preferentially elevated the quantal catch in surrounding S-cones, while stimulation of the same cones against a white background elicited green sensations. In one of two subjects, proximity to S-cones increased the probability of blue reports when M-cones were probed. We propose that M-cone increments excited both green and blue opponent pathways, but the relative activity of neighboring cones favored one pathway over the other.

scholarly journals Two calmodulins in Naegleria flagellates: characterization, intracellular segregation, and programmed regulation of mRNA abundance during differentiation.

1986 ◽  
Vol 102 (5) ◽  
pp. 1671-1678 ◽  
Author(s):  
C Fulton ◽  
K L Cheng ◽  
E Y Lai
Keyword(s):  
Molecular Weight ◽  
Wheat Germ ◽  
Apparent Molecular Weight ◽  
The Other ◽  
Free System ◽  
Intracellular Location ◽  
Coordinate Control ◽  
Weight One ◽  
Naegleria Gruberi ◽  
Stimulation Of

Flagellates of Naegleria gruberi contain two calmodulins that differ in apparent molecular weight and intracellular location. Calmodulin-1, localized in flagella, has an apparent molecular weight of approximately 16,000, approximately the size of other protozoan calmodulins, whereas calmodulin-2, localized in cell bodies, is 15,300. Both proteins, purified, are calmodulins by several criteria, including Ca2+-dependent stimulation of calmodulin-dependent cyclic nucleotide phosphodiesterase and affinity for antibodies to vertebrate calmodulin. The finding of two calmodulins is unusual. Since the only known difference is apparent molecular weight, one calmodulin could be derived from the other, except that both calmodulins are synthesized in a wheat germ, cell-free system directed by RNA from differentiating Naegleria. Translatable mRNAs encoding calmodulins 1 and 2, not detected in amebas, appear and subsequently disappear concurrently during the 100-min differentiation of Naegleria from amebas to flagellates. Furthermore, these mRNAs increase and then decrease in abundance concurrently with those for flagellar tubulins, which suggests the possibility that the expression of the unrelated genes for calmodulin and tubulin may be under coordinate control during differentiation.

Isolation and Characterization of Plasminogen Activator from Pig Leucocytes

1974 ◽  
Vol 31 (01) ◽  
pp. 072-085 ◽  
Author(s):  
M Kopitar ◽  
M Stegnar ◽  
B Accetto ◽  
D Lebez
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Gel Electrophoresis ◽  
Gel Filtration ◽  
Ph Optimum ◽  
Isolation And Characterization ◽  
Ph Range ◽  
Inhibition Studies ◽  
Final Purification

SummaryPlasminogen activator was isolated from disrupted pig leucocytes by the aid of DEAE chromatography, gel filtration on Sephadex G-100 and final purification on CM cellulose, or by preparative gel electrophoresis.Isolated plasminogen activator corresponds No. 3 band of the starting sample of leucocyte cells (that is composed from 10 gel electrophoretic bands).pH optimum was found to be in pH range 8.0–8.5 and the highest pH stability is between pH range 5.0–8.0.Inhibition studies of isolated plasminogen activator were performed with EACA, AMCHA, PAMBA and Trasylol, using Anson and Astrup method. By Astrup method 100% inhibition was found with EACA and Trasylol and 30% with AMCHA. PAMBA gave 60% inhibition already at concentration 10–3 M/ml. Molecular weight of plasminogen activator was determined by gel filtration on Sephadex G-100. The value obtained from 4 different samples was found to be 28000–30500.

The Kidney and Fibrinolysis

1970 ◽  
Vol 24 (01/02) ◽  
pp. 026-032 ◽  
Author(s):  
N. A Marsh
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Enzyme System ◽  
Normal Animal ◽  
Fibrinolytic Enzyme ◽  
The Other ◽  
Exclusion Chromatography ◽  
Normal Urine ◽  
Renal Origin ◽  
Molecular Exclusion Chromatography

SummaryMolecular exclusion chromatography was performed on samples of urine from normal and aminonucleoside nephrotic rats. Normal urine contained 2 peaks of urokinase activity, one having a molecular weight of 22,000 and the other around 200,000. Nephrotic urine contained three peaks of activity with MW’s 126,000, 60,000 and 30,000. Plasma activator determined from euglobulin precipitate had a MW. in excess of 200,000. The results indicate that in the normal animal, plasma plasminogen activator does not escape into the urine in substantial quantities but under the conditions of extreme proteinuria there may be some loss through the kidney. The alteration in urokinase output in nephrotic animals indicates a greatly disordered renal fibrinolytic enzyme system.The findings of this study largely support the hypothesis that plasma plasminogen activator of renal origin and urinary plasminogen activator (urokinase) are different molecular species.

Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Chain Structure ◽  
The Other ◽  
Single Chain ◽  
Apparent Homogeneity ◽  
Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

Endo-D-galacturonanase immobilized by adsorption on porous polyethyleneterephthalate

1982 ◽  
Vol 47 (10) ◽  
pp. 2716-2723 ◽  
Author(s):  
Lubomíra Rexová-Benková ◽  
Jiřina Omelková ◽  
Vladimír Kubánek
Keyword(s):  
Ionic Strength ◽  
High Stability ◽  
Relative Activity ◽  
Operational Stability ◽  
The Other ◽  
Fixation Strength ◽  
Action Pattern ◽  
Salt Solutions ◽  
Buffer Solution ◽  
Degradation Degree

Endo-D-galacturonanase of Aspergillus sp. was irreversibly adsorbed on polyethyleneterephthalate in an acetate 0.1 mol l-1 buffer solution of pH 4.2. Immobilization of the enzyme resulted in lowering of its activity, the measure of which depended on the amount of the enzyme fixed on the carrier. The highest relative activity (42.4%) had the preparation containing 5.25 mg of the enzyme per 1 g of the carrier. The velocity and intensity of the sorption of the enzyme depended on the ionic strength of the medium, whilst pH, on the other hand, was of no influence. Endo-D-galacturonanase immobilized in a 0.1 mol l-1 buffer was characteristic a) of its fixation strength in salt solutions of various ionic strength and pH, in a 3 mol l-1 guanidine solution, and also in sodium pectate and pectin solutions, b) of its high stability during a long-lasting storage at 4 °C, c) of its operational stability. The immobilization led to a partial change of the action pattern onto the high-molecular substrate, manifested in lowering the decrease of viscosity to degradation degree ratio.

Sign in / Sign up

Export Citation Format

Share Document