THE PENTOSE PHOSPHATE METABOLIC PATHWAY IN THE HUMAN ERYTHROCYTE: II. THE TRANSKETOLASE AND TRANSALDOLASE ACTIVITY OF THE HUMAN ERYTHROCYTE

1961 ◽  
Vol 39 (3) ◽  
pp. 533-543 ◽  
Author(s):  
Y. S. Brownstone ◽  
O. F. Denstedt
Keyword(s):  
Human Erythrocyte ◽  
Soluble Fraction ◽  
Pentose Phosphate ◽  
Ion Concentration ◽  
Thiamine Pyrophosphate ◽  
Magnesium Ions ◽  
Michaelis Constant ◽  
Hydrogen Ion Concentration ◽  
Wide Range ◽  
Human Red Cells

Transketolase, in the human erythrocyte, is confined to the soluble fraction of the cell. The activation energy for the formation of sedoheptulose-7-phosphate (S-7-P) from pentose phosphate was found to be 11,500 calories and the rate of formation of S-7-P to be directly proportional to the concentration of the enzyme. The Michaelis constant, with ribose-5-phosphate (R-5-P) as the added substrate, was found to be 6 × 10−3 M. The activity of the enzyme is close to the maximum over a wide range of hydrogen ion concentration (pH 7.1 to 8.3) with only a gradual decrease beyond these limits. The transketolase, in the dialyzed stroma-free hemolyzate, is active without the addition of magnesium ions or thiamine pyrophosphate. It is unaffected by sulphydryl-binding inhibitors and by EDTA and oxythiamine pyrophosphate.Transaldolase activity also has been demonstrated in the hemolyzate of human red cells. The rate of the production of hexose phosphate from sedoheptulose-7-phosphate was found to be of the order of 40 μmoles/g Hb/hour. The activity of the enzyme is close to the maximum between pH 7.18 and 7.75.

Specific Inhibition of Endotoxin Coating of Red Cells by a Human Erythrocyte Membrane Component

1970 ◽  
Vol 1 (1) ◽  
pp. 98-108
Author(s):  
Georg F. Springer ◽  
Shankar V. Huprikar ◽  
Erwin Neter
Keyword(s):  
Human Erythrocyte ◽  
Inhibitory Effect ◽  
Red Cells ◽  
Ion Concentration ◽  
Gram Negative Bacteria ◽  
Hydrogen Ion Concentration ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Common Antigens ◽  
Vi Antigen

We have isolated from human erythrocyte ghosts a fraction which prevents the attachment of unheated as well as heated lipopolysaccharides of gram-negative bacteria to red cells. This material has no significant inhibitory effect either toward the Vi antigen of gram-negative bacteria or towards the group and common antigens of the gram-positive bacteria investigated. We, therefore, named this fraction “lipopolysaccharide receptor.” The receptor interacts with lipopolysaccharides and not with erythrocytes, it forms complexes with and blocks those groupings of lipopolysaccharides which attach to red cells. The effect of the receptor is physical and not enzymatic. The interaction of the receptor with the lipopolysaccharides is reversible, and the receptor removes lipopolysaccharides fixed to red cells. An equilibrium of lipopolysaccharide distribution between cells and receptor is established when receptor-lipopolysaccharide complexes are incubated with red cells. The receptor is labile toward heat and deviation of the hydrogen ion concentration from neutrality; aldehydes destroy its inhibitory activity.

scholarly journals A Colorimetric Method for Studying the Dissociation of Oxyhæmocyanin suitable for Class Work

1925 ◽  
Vol 13 (4) ◽  
pp. 970-980 ◽  
Author(s):  
C. F. A. Pantin ◽  
Lancelot T. Hogben
Keyword(s):  
Marked Effect ◽  
Colorimetric Method ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Dissociation Curve ◽  
Hydrogen Ion Concentration ◽  
Laboratory Class ◽  
Wide Range ◽  
Increasing Temperature ◽  
Limits Of Error

1. A simple colorimetric method for plotting the dissociation curve of haemocyanin is indicated. The limits of error are within 5 per cent. The simplicity of the method commends it for laboratory class work.2. The effect of hydrogen ion concentration on the dissociation of the hsemocyanins of the crustacean Palinurus and the pulmonate Helix have been compared. In the snail change of hydrogen ion concentration over a wide range was not found to affect the dissociation of the hsemocyanin: in 'the crustacean there is a marked effect similar to that seen in the dissociation of hæmoglobin.3. The similarity of crustacean hsemocyanin to haemoglobin is also seen in that increasing temperature depresses the dissociation curve. The effects of certain salts upon haemocyanin. have also been recorded.

Nutritional studies of a flagellated protozoan Hexamita inflata from the Canadian oyster, Crassostrea virginica

1968 ◽  
Vol 14 (8) ◽  
pp. 817-821 ◽  
Author(s):  
B. T. Khouw ◽  
H. D. McCurdy Jr.
Keyword(s):  
Unsaturated Fatty Acids ◽  
Egg Yolk ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Wide Range ◽  
Simple Medium ◽  
Nutritional Studies ◽  
Vitamin Mixture ◽  
Anaerobic Environment

The physical and nutritional requirements for growth of Hexamita inflata have been studied in axenic cultures. The flagellate was capable of growing over a wide range of temperature (5 °C to 25 °C), of hydrogen ion concentration (pH 4.5 to 8.5), and of salinity (3 to 28‰); and required a reducing or anaerobic environment. The requirement of an egg-yolk suspension for growth was partially satisfied by unsaturated fatty acids. Attempts to replace the peptone by mixtures of amino acids were not successful. A simple medium containing a vitamin mixture, linoleic acid, glucose, cysteine, peptone, and salt has been formulated.

scholarly journals STIMULATION BY HYDROCHLORIC ACID IN THE CATFISH, SCHILBEODES

1931 ◽  
Vol 15 (2) ◽  
pp. 119-124 ◽  
Author(s):  
William H. Cole ◽  
James B. Allison
Keyword(s):  
Reaction Time ◽  
Hydrochloric Acid ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Acid Molecule ◽  
Experimental Conditions ◽  
Hydrogen Ion Concentration ◽  
Effective Stimulus ◽  
Wide Range ◽  
Increasing Function

1. The reaction of the catfish, Schilbeodes gyrinus Mitchill, to hydrochloric acid over a wide range of concentrations (from pH 1.82 to pH 6.83) has been studied under experimental conditions which reduced to a minimum all other stimuli. 2. As the [H+J increases within the limits mentioned, the reaction time of the fish decreases. In other words, the rate of the stimulation processes is an increasing function of the hydrogen ion concentration. 3. The effective stimulus is the hydrogen ion, since NaCl solutions of equivalent concentration were not stimulating. 4. Stimulation by hydrochloric acid is therefore correlated with the potential of the cation resulting from dissociation of the acid molecule.

scholarly journals THE EFFECT OF HYDROGEN ION CONCENTRATION ON SWELLING OF CELLS

1926 ◽  
Vol 9 (5) ◽  
pp. 709-714 ◽  
Author(s):  
Baldwin Lucke ◽  
Morton McCutcheon
Keyword(s):  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Ph Values ◽  
Wide Range

1. The effect of HCl, NaOH, CO2, and NH3 on the volume of unfertilized Arbacia eggs was tested over a wide range of pH values. 2. No swelling occurred, except in HCl solutions, and there not until after injury or death had occurred. 3. Whereas the volume of erythrocytes and of proteins such as gelatin is known to be dependent on the pH of the solution, such a relation does not exist in the case of living and uninjured cells, at least of the type tested.

Effects of pH on excitation and contraction in frog twitch muscle

1977 ◽  
Vol 55 (3) ◽  
pp. 709-723 ◽  
Author(s):  
J. G. Foulks ◽  
Florence A. Perry
Keyword(s):  
Membrane Potential ◽  
Action Potentials ◽  
Time Course ◽  
Calcium Concentration ◽  
Divalent Cations ◽  
Ion Concentration ◽  
Resting Potential ◽  
Hydrogen Ion Concentration ◽  
Wide Range ◽  
Effects Of Ph

The electrical and mechanical behaviour of frog twitch muscle in response to changes in membrane potential has been examined over a wide range of hydrogen ion concentration (pH 3.0–11.0). The changes in resting and action potentials, twitches, and maximum potassium-induced contractures (K contractures) were remarkably small when the pH was varied between 5.0 and 10.0. The time course of action potentials generally displayed small graded changes with variation in pH, possibly as the result of changes in surface potential.The amplitude of twitches and maximum K contractures was substantially decreased when pH was reduced to 4.0 or raised to 11.0 without significant alteration in membrane resting potential or consistent suppression of excitation, but maximum caffeine-induced contractures were unchanged. Replacement of chloride with perchlorate promptly antagonized the depressant effects of pH extremes (4.0, 11.0) on both twitch amplitude and maximum K-contracture tension. Acid-induced reductions in maximum K-contracture tension also were partially antagonized by increased calcium concentration. The onset and recovery from the contraction-depressant effects of pH extremes were too slow to be explained by the titration of groups immediately accessible at the membrane surface but too rapid to be accounted for by changes in intracellular pH. Thus, excitation and contraction apparently were uncoupled by sufficient alteration in extracellular pH. Changes in external pH had little effect on the impairment of maximum K contractures by media lacking divalent cations, or on the restoration of such responses by perchlorate except at very alkaline pH (10.0–11.0).The threshold for K contractures was reduced at pH 11.0, but otherwise was little affected by variation in pH at normal concentrations of divalent cations. Altered pH did not modify the usual effects of increased calcium concentration on the relation between potassium concentration and K-contracture tension. When K contractures were maintained by perchlorate in the absence of divalent cations, hydrogen ions displayed calcium-like actions on the relation between external K concentration ([K]0) and K-contracture tension, and also on the time course of submaximum K contractures. These observations are compatible with similar effects of hydrogen and calcium ions on surface potential.The problem of identifying putative charged groups which might influence the linkage between contractile responses and changes in membrane potential is discussed.

Effect of acute changes in the PaCO2 on acid–base parameters in normal dogs and dogs with metabolic acidosis or alkalosis

1983 ◽  
Vol 61 (2) ◽  
pp. 166-173 ◽  
Author(s):  
M. Bercovici ◽  
C. B. Chen ◽  
M. B. Goldstein ◽  
B. J. Steinbaugh ◽  
M. L. Halperin
Keyword(s):  
Metabolic Acidosis ◽  
Linear Relationship ◽  
Regression Line ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Gastrointestinal Fluid ◽  
Wide Range ◽  
State Formula ◽  
Acute Changes

There is a linear relationship between the [Formula: see text] and blood hydrogen ion concentration in normal dogs, but for theoretical reasons to be discussed, we questioned whether this relationship would apply in animals with metabolic acidosis or alkalosis. To study this in more detail, animals were divided into three groups: normal, metabolically acidotic, and metabolically alkalotic. Following anesthesia and bilateral ureteral ligation, dogs were intubated and ventilated to produce acute steady-state [Formula: see text] values corresponding to the range observed during disease states. Changes in the volume and electrolyte composition of the gastrointestinal fluid and urine as well as the concentration and distribution of lactate were evaluated in all experiments. We observed the previously described linear relationship between the [Formula: see text] and blood hydrogen ion concentration in normal dogs, but the slope of the regression line differed significantly from those of dogs with metabolic acidosis and metabolic alkalosis. On the other hand, there was a consistent relationship between the ratio of the [Formula: see text] values, but not the absolute [Formula: see text], and the change in the plasma bicarbonate concentration over a wide range of [Formula: see text] values in all groups of dogs. The chemical basis for these observations will be discussed.

Studies on Azotobacter in Malayan soils

1936 ◽  
Vol 26 (2) ◽  
pp. 268-280 ◽  
Author(s):  
R. A. Altson
Keyword(s):  
Calcium Carbonate ◽  
Calcium Chloride ◽  
Culture Medium ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Lag Phase ◽  
Hydrogen Ion Concentration ◽  
Factors Associated ◽  
Wide Range

These observations have shown that the strains of Azotobacter occurring in certain Malayan soils are unable to initiate growth on standard media, except after a lag phase of considerable duration. Evidence has been obtained which suggests that this inability is not necessarily an indication of a scarcity of the organisms in the soil used as an inoculum, but may be due to factors associated with the composition of the culture medium.In particular the strains of Azotobacter developing from these soils are checked by the presence of calcium carbonate in the medium. They will grow well in a medium in which calcium chloride replaces calcium carbonate, but equally well where the medium contains but traces of calcium.These strains can tolerate a wide range of hydrogen-ion concentration extending on the acid side to pH. 3·6. Their existence invalidates the use for these soils of all such microbiological tests of lime requirement as make use of Azotobacter as indicator.

THE PENTOSE PHOSPHATE METABOLIC PATHWAY IN THE HUMAN ERYTHROCYTE: III. THE STABILITY OF THE PENTOSE PHOSPHATE METABOLIC SYSTEM IN PRESERVED ERYTHROCYTES

1961 ◽  
Vol 39 (3) ◽  
pp. 545-550 ◽  
Author(s):  
Y. S. Brownstone ◽  
O. F. Denstedt
Keyword(s):  
Metabolic Pathway ◽  
Human Erythrocyte ◽  
Pentose Phosphate ◽  
Red Cells ◽  
Prolonged Storage ◽  
Metabolic System ◽  
The Stability ◽  
Citrate Dextrose ◽  
Human Red Cells

The activity of the enzymes of the pentose phosphate metabolic pathway in the dialyzed stroma-free hemolyzate (SFH) from human red cells remains unaltered after prolonged storage of the blood in acidified citrate dextrose (ACD) medium at 4 °C.Erythrocytes from children with galactosemia were found to have normal transketolase and transaldolase activity.

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