PREPARATION AND HEAT DENATURATION OF THE GLUTEN PROTEINS

1931 ◽  
Vol 5 (4) ◽  
pp. 389-406 ◽  
Author(s):  
W. H. Cook
Keyword(s):  
Elevated Temperatures ◽  
Marked Decrease ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Heat Denaturation ◽  
Hydrogen Ion Concentration ◽  
Gluten Proteins ◽  
Buffer Solutions ◽  
Natural Moisture Content ◽  
Low Solubility

Gliadin prepared by several different methods had the same nitrogen content and distribution. The critical peptization temperature (C.P.T.) in 60% alcohol and viscosity in 30% urea-buffer solutions, however, showed considerable variation, preparations of high C.P.T. (low solubility) being more viscous. This variation in the physical properties is explained by fractionation or denaturation incidental to the method of preparation.Gluten precipitated from 30% urea solutions at salt concentrations varying from 0.1 to 0.5 of saturation, yielded fractions that varied continuously in their gliadin and glutenin content, as judged from their percentage of arginine nitrogen.Gluten dispersed in buffered 30% urea solutions showed no change in viscosity during 101 hr. after the gluten was completely dispersed. A variation of hydrogen ion concentration between pH 6.0 and 6.95 had little effect on its viscosity. Heating at 70 °C. caused a marked decrease in the viscosity of this dispersion during the first hour. When gliadin dispersions are heated as above only samples having a high initial viscosity and C.P.T. become less viscous. Heating gliadin of natural moisture content (12 to 14%) at 70 °C. for varying periods of time did not change significantly its subsequent C.P.T. and viscosity in 60% alcohol. More severe heat treatments at higher moisture contents rendered the gliadin insoluble in 60% alcohol. Dilute alcoholic extracts of heated flours contained less protein than those of unheated controls. However, the C.P.T. of the former was lower than that of the latter. It is concluded from these experiments that when the gluten proteins are subjected to elevated temperatures, the glutenin fraction is first affected, next the gliadin fractions of low solubility, and finally, under severe conditions, all of the gliadin is denatured.

scholarly journals THE ELIMINATION OF DISCREPANCIES BETWEEN OBSERVED AND CALCULATED P.D. OF PROTEIN SOLUTIONS NEAR THE ISOELECTRIC POINT WITH THE AID OF BUFFER SOLUTIONS

1922 ◽  
Vol 4 (5) ◽  
pp. 617-619 ◽  
Author(s):  
Jacques Loeb
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Isoelectric Point ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Protein Solutions ◽  
Protein Solution ◽  
Hydrogen Ion Concentration ◽  
Buffer Salt ◽  
Buffer Solutions

1. It had been noticed in the previous experiments on the influence of the hydrogen ion concentration on the P.D. between protein solutions inside a collodion bag and aqueous solutions free from protein that the agreement between the observed values and the values calculated on the basis of Donnan's theory was not satisfactory near the isoelectric point of the protein solution. It was suspected that this was due to the uncertainty in the measurements of the pH of the outside aqueous solution near the isoelectric point. This turned out to be correct, since it is shown in this paper that the discrepancy disappears when both the inside and outside solutions contain a buffer salt. 2. This removes the last discrepancy between the observed P.D. and the P. D. calculated on the basis of Donnan's theory of P.D. between membrane equilibria, so that we can state that the P.D. between protein solutions inside collodion bags and outside aqueous solutions free from protein can be calculated from differences in the hydrogen ion concentration on the opposite sides of the membrane, in agreement with Donnan's formula.

Changes in pH, Carbonate and Lactate of the Blood of Yearling Kamloops Trout, Salmo gairdneri, During and Following Severe Muscular Activity

1959 ◽  
Vol 16 (4) ◽  
pp. 391-402 ◽  
Author(s):  
Edgar C. Black ◽  
Wing-gay Chiu ◽  
Francis D. Forbes ◽  
Arthur Hanslip
Keyword(s):  
Marked Decrease ◽  
Initial Level ◽  
Muscular Activity ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Salmo Gairdneri ◽  
Blood Levels ◽  
Hydrogen Ion Concentration ◽  
Initial Rise ◽  
Initial Figure

Alterations in the blood levels of lactate, carbonate, hydrogen ion and hemoglobin following vigorous muscular exercise were studied in yearling Kamloops trout, Salmo gairdneri, over four years.Lactate increased during exercise and during the first 2 hours of rest, returning to the initial level after 6 to 8 hours. Carbonate increased to a maximum during the first 3 minutes of exercise, then dropped precipitously to a minimum far below the initial level after [Formula: see text] hour of rest, later rose to near the initial level at the 4th hour of recovery, maintained this until the 12th hour, but it had decreased again at the 24th hour. Hydrogen ion concentration rose sharply during the first 3 minutes of activity, then fell off to a stable level a little above the initial figure until the end of exercise, after which it fell substantially below initial level and had not completely recovered after 24 hours of rest. A marked decrease in swimming rate occurred after 3 minutes exercise, following the initial rise of carbonate and hydrogen ion concentration.

On the colorimetric determination of hydrogen-ion concentration in soils

1923 ◽  
Vol 13 (1) ◽  
pp. 69-73 ◽  
Author(s):  
C. T. Gimingham
Keyword(s):  
Colorimetric Method ◽  
The Other ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Colorimetric Determination ◽  
Hydrogen Ion Concentration ◽  
Electrometric Method ◽  
Buffer Solutions ◽  
Special Apparatus

Of the two available methods for the determination of hydrogen-ion concentration, the electrometric is the more fundamental and satisfactory but it requires somewhat elaborate and expensive apparatus. The colorimetric method, on the other hand, though not lacking in difficulties if accurate results are wanted, requires no special apparatus and the actual procedure is simple. It is based on the electrometric method, and involves the use of buffer solutions of known hydrogen-ion concentration determined originally electrometrically.

THE INFLUENCE OF HYDROGEN ION CONCENTRATION WITH PRETREATMENT OF WOOD ON ITS SUBSEQUENT DELIGNIFICATION

1935 ◽  
Vol 13b (5) ◽  
pp. 289-295 ◽  
Author(s):  
A. J. Corey ◽  
O. Maass
Keyword(s):  
Previous Investigation ◽  
Ph Value ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Forced Flow ◽  
Effect Of Temperature ◽  
Hydrogen Ion Concentration ◽  
Temperature Range ◽  
Wood Meal ◽  
Buffer Solutions

The results obtained by the authors in a previous investigation have been checked. The influence of an acid, a salt and a base on the pretreatment of wood at 130 °C. has been determined. It is shown that pretreatment of wood meal decreases the rate of subsequent delignification. Pretreatment was carried out over the temperature range 100° to 140 °C. and the effect of temperature is shown to be very marked. As it was found that the pH of the water after pretreatment decreased, pretreatment was carried out on a chip in which the pH was kept more constant by a forced flow of water through the chip. It is shown that the rate of delignification is increased. Pretreatment was carried out in buffer solutions and it is shown that there is a pH value for which the influence of pretreatment is a minimum. The inferences drawn in connection with sulphite cooking are briefly discussed.

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