THE ENOLASE OF THE HUMAN ERYTHROCYTE

1962 ◽  
Vol 40 (8) ◽  
pp. 1005-1018 ◽  
Author(s):  
Rhoda Blostein ◽  
Orville F. Denstedt
Keyword(s):  
Kinetic Study ◽  
Human Erythrocyte ◽  
Hydrogen Ion ◽  
Active Complex ◽  
Ion Concentrations ◽  
Enzyme Substrate ◽  
Low Concentrations ◽  
Absolute Requirement ◽  
Wide Range ◽  
High Concentrations

The enolase activity of the human erythrocyte has been studied with a partially purified preparation of the enzyme. The enzyme was found to have an absolute requirement for Mg2+ions. A kinetic study of the influence of the concentration of Mg ions and 2-phosphoglycerate on the formation of phosphoeno/pyruvate from 2-phosphoglycerate has shown that the active complex of enzyme, substrate, and activator (Mg2+) can be formed in several ways. With low concentrations of substrate and Mg2+the reaction was maximum at pH 7.0; with high concentrations of both, the activity was maximum over a wide range of hydrogen ion concentrations on the acid side of neutrality (at least from pH 6.3 to 7.0) and decreased above pH 7.0.

THE ENOLASE OF THE HUMAN ERYTHROCYTE

1962 ◽  
Vol 40 (1) ◽  
pp. 1005-1018
Author(s):  
Rhoda Blostein ◽  
Orville F. Denstedt
Keyword(s):  
Kinetic Study ◽  
Human Erythrocyte ◽  
Hydrogen Ion ◽  
Active Complex ◽  
Ion Concentrations ◽  
Enzyme Substrate ◽  
Low Concentrations ◽  
Absolute Requirement ◽  
Wide Range ◽  
High Concentrations

The enolase activity of the human erythrocyte has been studied with a partially purified preparation of the enzyme. The enzyme was found to have an absolute requirement for Mg2+ions. A kinetic study of the influence of the concentration of Mg ions and 2-phosphoglycerate on the formation of phosphoeno/pyruvate from 2-phosphoglycerate has shown that the active complex of enzyme, substrate, and activator (Mg2+) can be formed in several ways. With low concentrations of substrate and Mg2+the reaction was maximum at pH 7.0; with high concentrations of both, the activity was maximum over a wide range of hydrogen ion concentrations on the acid side of neutrality (at least from pH 6.3 to 7.0) and decreased above pH 7.0.

Effects of polymethoxylated flavone metabolites on apoB100 secretion and MTP activity in Huh7.5 cells

2021 ◽  
Vol 18 ◽  
Author(s):  
Danielle R. Gonçalves ◽  
Thais B. Cesar ◽  
John A. Manthey ◽  
Paulo I. Costa
Keyword(s):  
Lipid Synthesis ◽  
Dependent Manner ◽  
Transfer Protein ◽  
Low Concentrations ◽  
Wide Range ◽  
Cell Assays ◽  
Polymethoxylated Flavones ◽  
High Concentrations

Background: Citrus polymethoxylated flavones (PMFs) reduce the synthesis of liver lipoproteins in animal and in vitro cell assays, but few studies have evaluated the direct effects of their metabolites on this highly regulated process. Objective: To investigate the effects of representative metabolites of PMF on the secretion of liver lipoproteins using the mammalian cell Huh7.5. Method: In this study, the influences of three PMFs and five previously isolated PMF metabolites on hepatic apoB-100 secretion and microsomal transfer protein (MTP) activity were evaluated. Tangeretin (TAN), nobiletin (NOB) and 3,5,6,7,8,3′,4′-heptamethoxyflavone (HMF), and their glucuronides (TAN-Gluc, NOB-Gluc and HMF-Gluc) and oxidatively demethylated metabolites (TAN-OH, NOB-OH, HMF-OH) were incubated with Huh7.5 cells to measure their inhibitory effects on lipid synthesis. Results: The results showed that TAN, HMF and TAN-OH reduced the secretion of apoB-100 in a dose-dependent manner, while NOB and the other tested metabolites showed no inhibition. MTP activity in the Huh7.5 cells was significantly reduced in the presence of low concentrations of TAN, and in high concentrations of NOB-OH. This study also showed that PMFs and PMF metabolites produced a wide range of effects on apoB-100 secretion and MTP activity. Conclusion: The results suggest that while PMFs and their metabolites control dyslipidemia in vivo, the inhibition of MTP activity cannot be the only pathway influenced by these compounds.

scholarly journals BIOLOGICAL AND PHYSICAL PROPERTIES OF THE HEMOTOXIN OF STREPTOCOCCI

1920 ◽  
Vol 32 (6) ◽  
pp. 639-650 ◽  
Author(s):  
Percy D. Meader ◽  
George H. Robinson
Keyword(s):  
Culture Medium ◽  
Considerable Extent ◽  
Water Soluble ◽  
Hydrogen Ion ◽  
Prolonged Heating ◽  
Ion Concentrations ◽  
Inorganic Substances ◽  
Wide Range ◽  
Unknown Composition ◽  
Unknown Component

The hemotoxin of streptococcus is a labile substance affected by centrifugation or shaking. It is adsorbed by various organic and inorganic substances. Hemotoxin is produced within a wide range of hydrogen ion concentrations. It is neither in nor on the bacterial cell but is free in the culture medium. It is probably not an enzyme. There are at least two substances which are essential to the medium for the elaboration of hemotoxin, one of which is phosphorus; the other is a substance of unknown composition. The unknown component is present in small quantities in unfiltered muscle infusion, but is more abundantly supplied by blood serum and kidney infusion. This substance is not an albumin, globulin, primary or secondary proteose, metaprotein, or peptone of the medium or enriching fluid. It is water-soluble, is destroyed by boiling in alkaline solution and by prolonged heating, and is removed to a considerable extent by passage through a diatomaceous filter.

scholarly journals Combined action of binase and bleomycin toward human lung adenocarcinoma cells

2016 ◽  
Vol 62 (3) ◽  
pp. 279-282 ◽  
Author(s):  
P.V. Zelenikhin ◽  
A.V. Makeeva ◽  
T.N. Nguen ◽  
Y.A. Siraj ◽  
O.N. Ilinskaya
Keyword(s):  
Lung Adenocarcinoma ◽  
Human Lung ◽  
A549 Cells ◽  
Chemotherapeutic Agents ◽  
Human Lung Adenocarcinoma ◽  
Low Concentrations ◽  
Wide Range ◽  
Bacillus Pumilus Rnase ◽  
High Concentrations ◽  
Lung Adenocarcinoma A549

Some microbial ribonucleases (RNases) demonstrate selective cytotoxic effect against a wide range of tumor cells. In this context combined use of cytotoxic RNases in complex therapy with other chemotherapeutic agents appears to be especially promising. In this study we have investigated the apoptosis-induced effect of Bacillus pumilus RNase (binase) in combination with known anti-tumor antibiotic bleomycin on human lung adenocarcinoma A549 cells. The combined effect of high concentrations of these agents did not have any mutual increase in their apoptosis-induced action, while a combination of non-apoptotic concentrations resulted in the increase of the proportion of apoptotic cells up to 22% as compared with individual effect of bleomycin (6%) and binase (12%) used separately. These results indicate that binase and bleomycin are effective in combination of their low concentrations and ineffective in combination of their high concentrations.

A bioassay for systemic fungicides using axenic cultures of the carnation rust fungus, Uromyces dianthi

1973 ◽  
Vol 51 (10) ◽  
pp. 2004-2006 ◽  
Author(s):  
D. R. Jones
Keyword(s):  
Inhibitory Action ◽  
Agar Medium ◽  
Rust Fungus ◽  
Screening Programs ◽  
Systemic Fungicides ◽  
Low Concentrations ◽  
Wide Range ◽  
Axenic Cultures ◽  
High Concentrations

The inhibitory action of three systemic fungicides (Benlate, Hoe 6053, and Milstem) on the growth of axenic cultures of the carnation rust fungus, Uromyces dianthi, was assessed. The rust- and smut-specific fungicide (Hoe 6053) was found to inhibit growth when present in the agar medium in very low concentrations, while moderate concentrations of the wide range fungicide (Benlate), and high concentrations of the powdery mildew-specific fungicide (Milstem) were needed for inhibition. The results indicated the possible use of U. dianthi in future in vitro fungicide screening programs and mode-of-action studies.

The use of chromium oxide to estimate the faecal output of Merinos

1963 ◽  
Vol 14 (2) ◽  
pp. 239 ◽  
Author(s):  
LJ Lambourne ◽  
TF Reardon
Keyword(s):  
Chromium Oxide ◽  
Grab Sampling ◽  
Low Concentrations ◽  
Wide Range ◽  
Main Series ◽  
Series Of Experiments ◽  
The Mean ◽  
High Concentrations ◽  
Fixed Times ◽  
Selection Of

The pattern of chromium oxide (Cr2O3) excretion was studied in Merino wethers. The sheep were dosed twice daily with Cr2O3 at fixed times. In the main series of experiments, sheep were fed fresh herbage in metabolism pens. An oaten chaff diet was also employed. In all cases a diurnal pattern of Cr2O3 excretion in the faeces was observed. The pattern was not consistent from day to day, nor was there any consistent effect of level of intake or feeding frequency on the excretion pattern. Distributions of Cr2O3 were examined in eight grazing sheep killed ½–4 hr after dosing. In six of the animals high concentrations of the marker were found to be mixed with the reticuloruminal ingesta, while low concentrations were observed in the other stomachs. In the remaining two animals high concentrations were observed in the omasum and abomasum, from which it was inferred that the dose had by-passed the main bulk of the reticulorurninal ingesia. It seems unlikely that any real advantage is to be gained by painstaking selection of particular times for dosing and faeces sampling in different environments; and it is suggested that convenient fixed times — say 6 a.m. and 3 p.m., or 9 a.m. and 5 p.m. — should prove satisfactory in estimating output of faeces of grazing animals under a wide range of conditions. In 40 sheep-periods of 10–14 days, the mean daily output of faeces organic matter by pen-fed wethers was estimated with mean 101% and error ±12% of the true figures, by analysis of a single bulked sample obtained by dosing and grab sampling at about 9 a.m. and 5 p.m. daily. In 40 periods when samples were bulked over 5–7 days the average estimate was 102 ± 14% of the true figure. Comparison under extensive grazing conditions showed that estimates obtained by dosing and sampling only once per day were generally some 15% higher than those obtained by dosing and sampling twice daily.

scholarly journals The Effect of Fuel Composition Upon Combustion Performance in a Rolls Royce Tyne Combustor

1985 ◽  
Author(s):  
T. T. Bowden ◽  
J. H. Pearson
Keyword(s):  
Hydrogen Content ◽  
Smoke Point ◽  
Fuel Combustion ◽  
Polycyclic Aromatics ◽  
Turbine Engine ◽  
Combustion Performance ◽  
Low Concentrations ◽  
Wide Range ◽  
High Concentrations ◽  
Specification Requirement

The combustion performance of a wide range of fuel types has been examined utilizing a single combustor from a Rolls-Royce Tyne gas-turbine engine. The results provide further evidence to suggest that fuel total hydrogen content provides a better indication of fuel combustion perfomance than does aromatic content. However, an even better prediction of fuel combustion performance is given by smoke point, although the acknowledged imprecision of the smoke point test does militate against its use as a primary specification requirement. Analysis of certain fuels by 13C NMR and low resolution mass spectroscopy demonstrates that it is those fuels with high concentrations of polycyclic aromatics whose combustion performance in terms of flame radiation and exhaust emissions, is underpredicted by fuel total hydrogen content. There are indications that low concentrations of high molecular weight polycyclic aromatics may substantially impair combustion performance.

A kinetic study of the chlorination of ketones by chloramine-T: Novel concentration dependences on the chlorinating agent and the ketones

1976 ◽  
Vol 29 (7) ◽  
pp. 1449 ◽  
Author(s):  
V Balasubramanian ◽  
V Thiagarajan
Keyword(s):  
Acetic Acid ◽  
Kinetic Study ◽  
Acidic Medium ◽  
Aqueous Acetic Acid ◽  
Acetic Acid Medium ◽  
Rate Determining Step ◽  
Low Concentrations ◽  
Concentration Dependences ◽  
Chloramine T ◽  
High Concentrations

The chlorination of acetone in aqueous acidic medium in the presence of acetic acid and dimethylformamide was subjected to kinetic study. Although the kinetics follows the traditional mechanism at high concentrations of chloramine-T (cat) and in aqueous acetic acid in the presence of sodium acetate, a term in the rate law independent of ketone concentration is reported for the first time in strongly acidic medium at low concentrations of chloramine-T. Generation of the chlorinating species is considered as the rate-determining step (Scheme 1). The mechanistic changes which occur on addition of chloride and on changing the structure of the ketone are reported. The effect of acetate on the rate in aqueous acetic acid medium is rationalized by invoking a prior equilibrium formation of enolate followed by a rate-controlling chlorination by chlorinium acetate. The retardation in rate and the consequent changes in mechanism in the case of p-bromo- and p-nitroacetophenone are accounted for by invoking a complex between the enol and the positive chlorine species similar to that in the mechanism for the chlorination of phenols.

scholarly journals ELECTROPHORETIC HOMOGENEITY OF PREGNANT MARE SERUM GONADOTROPHIN

1940 ◽  
Vol 23 (6) ◽  
pp. 733-739 ◽  
Author(s):  
Choh Hao Li ◽  
Herbert M. Evans ◽  
Donald H. Wonder
Keyword(s):  
Room Temperature ◽  
Chemical Constituents ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Hydrogen Ion ◽  
Amino Groups ◽  
Ion Concentrations ◽  
Wide Range ◽  
Tyrosine Content ◽  
Pregnant Mare Serum Gonadotrophin

A highly purified and potent gonadotrophin in pregnant mare serum has been prepared. The preparation has been shown to be electrophoretically homogeneous in the Tiselius apparatus. The mobilities of the substance have been determined over a wide range of hydrogen ion concentrations. The isoelectric point lies at pH 2.60–2.65 and the value of See PDF for Equation is 4.0 x 10–5. Some chemical constituents have been studied. From the tryptophane and tyrosine content the molecular weight of the hormone is estimated to be 30,000. The hormone has been subjected to acetylation by ketene in aqueous solution at room temperature and the result suggests again the essentiality of free amino groups for the biological activity of the hormone. In this respect it is to be contrasted with human chorionic gonadotrophin.

Modeling Peroxidase-Oxidase Interactions

2011 ◽  
Author(s):  
W. M. Schaffer ◽  
T. V. Bronnikova
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Low Concentrations ◽  
Wide Range ◽  
Regulatory Capacity ◽  
Episodic Nature ◽  
High Concentrations

Reactive oxygen species (ROS) and peroxidase-oxidase (PO) reactions are Janus-faced contributors to cellular metabolism. At low concentrations, reactive oxygen species serve as signaling molecules; at high concentrations, as destroyers of proteins, lipids and DNA. Correspondingly, PO reactions are both sources and consumers of ROS. In the present paper, we study a well-tested model of the PO reaction based on horseradish peroxidase chemistry. Our principal predictions are these: 1. Under hypoxia, the PO reaction can emit pulses of hydrogen peroxide at apparently arbitrarily long intervals. 2. For a wide range of input rates, continuing infusions of ROS are transduced into bounded dynamics. 3. The response to ROS input is hysteretic. 4. With sufficient input, regulatory capacity is exceeded and hydrogen peroxide, but not superoxide, accumulates. These results are discussed with regard to the episodic nature of neurodevelopmental and neurodegenerative diseases that have been linked to oxidative stress and to downstream interactions that may result in positive feedback and pathology of increasing severity.

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