The role of salts, hydrogen-ion concentration and agar in the response of the Avena coleoptile to auxins

PROTOPLASMA ◽  
1939 ◽  
Vol 32 (1) ◽  
pp. 307-308
Keyword(s):  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Avena Coleoptile

scholarly journals Studies in the mechanism of enzyme action. I.—Rôle of the reaction of the medium in fixing the optimum temperature of a ferment

1921 ◽  
Vol 92 (642) ◽  
pp. 1-6 ◽  
Keyword(s):  
Enzyme Activity ◽  
Temperature Effect ◽  
Acid Medium ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Optimum Temperature ◽  
Hydrogen Ion Concentration ◽  
Enzyme Action

Previously, it has been shown for the enzyme maltase —enzyme requiring an acid medium in which to act to best advantage—that increase in the acidity or hydrogen ion concentration of the medium in which the enzyme acts, beyond the optimum acidity, leads to a fall of optimum temperature. The mechanism of his temperature of this temperature effect appears clearly to be due to a certain disablement of the enzyme activity, estimated at the optimum temperature point; which decrease of activity is itself a function of the degree of acidity of the medium in excess of that necessary to produce optimum activation. Being in this way a disablement effect, the question arises whether, by adding to the quantity of enzyme in action, the lowering of optimum temperature which takes place can be controlled. To answer that question, the experiments described in the present paper were undertaken. For the investigation, the enzyme used is the maltase of Aspergillus oryzœ , the same preparation being employed as studied by us in two previous communications, a specially active specimen of takadiastase, purified by repeated solution in water and reprecipitation by alcohol.

THE HYDROLYSIS OF THE CONDENSED PHOSPHATES: II (A). THE ROLE OF THE HYDROGEN ION IN THE HYDROLYSIS OF SODIUM PYROPHOSPHATE: II (B). THE DISSOCIATION CONSTANTS OF PYROPHOSPHORIC ACID

1954 ◽  
Vol 32 (2) ◽  
pp. 174-185 ◽  
Author(s):  
J. D. McGilvery ◽  
Joan Pedley Crowther
Keyword(s):  
Dissociation Constants ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Rate Equations ◽  
Hydrogen Ion Concentration ◽  
Pyrophosphoric Acid ◽  
Condensed Phosphates ◽  
Anionic Species ◽  
Hydrolysis Of

The general rate equations for the hydrolysis of pyrophosphate anion proposed by Muus have been proved to be inapplicable over the pH range 2.0 to 11.0. A general rate equation is proposed which is based on the assumption that each anionic species of pyrophosphoric acid hydrolyzes at a rate which depends on its concentration, and that the only role of the hydrogen ion concentration is to determine the proportion of each species present in the solution. A mechanism for the hydrolysis of pyrophosphate anion is suggested.The dissociation constants of pyrophosphoric acid have been determined at 65.5 °C. for the concentration range 0.08 to 0.18 molar.

scholarly journals Role of The CO2System in Regulating Intramuscular Hydrogen Ion Concentration during Exercise in Horses

2014 ◽  
Vol 46 ◽  
pp. 15-15 ◽  
Author(s):  
M Vengust ◽  
J Richards ◽  
H Staempfli ◽  
L Viel ◽  
G Heigenhauser
Keyword(s):  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration
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