Some Characteristics of the Enzymes of the Pyloric Caeca of Cod and Haddock

1937 ◽  
Vol 3 (5) ◽  
pp. 473-485 ◽  
Author(s):  
W. W. Johnston
Keyword(s):  
Protease Activity ◽  
Room Temperature ◽  
Maximum Activity ◽  
Hydrogen Ion ◽  
Ammonium Salts ◽  
Ion Concentrations ◽  
Pyloric Caeca ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Partial Vacuum

Investigation of fish enzymes for leather bates reveals that those of the pyloric caeca show their greatest influence on casein and collagen at hydrogen ion concentrations of approximately pH 8. The protease showed its maximum activity towards casein at a temperature of 45 °C. Ammonium salts at certain concentrations increased the rate of hydrolysis of collagen by about 40 per cent, but had no like stimulating effect on the hydrolysis of casein. A comparison showed that pyloric caeca enzymes were just as satisfactory as commercial leather bates or hog pancreas. When the pyloric caeca are allowed to autolyse at room temperature, the protease activity is constant for the first 24 hours, declines rapidly during the next 80 hours, and slowly thereafter. The most suitable method for preparing a dried preparation was by evaporation under partial vacuum, which, however, is accompanied by some loss of activity.

THE HYDROLYSIS OF THE CONDENSED PHOSPHATES: III. SODIUM TETRAMETAPHOSPHATE AND SODIUM TETRAPHOSPHATE

1956 ◽  
Vol 34 (7) ◽  
pp. 969-981 ◽  
Author(s):  
Joan Crowther ◽  
A. E. R. Westman
Keyword(s):  
Phosphate Glass ◽  
Sodium Phosphate ◽  
Hydrogen Ion ◽  
Ion Concentrations ◽  
First Order ◽  
Condensed Phosphates ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Ph Range ◽  
Hydrolysis Of

The rates of hydrolysis of sodium tetrametaphosphate and tetraphosphate (in the presence of tetrametaphosphate) have been measured at 65.5 °C. over the pH range 2.5 to 13.3. Tetrametaphosphate anions hydrolyze to tetraphosphate which in turn hydrolyzes to triphosphate and orthophosphate and not to pyrophosphate. Thus the terminal oxygen bridges in the tetraphosphate and not the central one are attacked preferentially. The reactions were first order and acid catalyzed. The tetrametaphosphate hydrolysis was also base catalyzed with a minimum rate in solutions of pH approximately 7.5. The rate of hydrolysis of tetraphosphate was greater than triphosphate at the hydrogen ion concentrations studied. Hydrolysis of a sodium phosphate glass indicated that preferential attack on terminal oxygen bridges takes place also with higher polymers. However, trimetaphosphate is formed at the same time.

ÉTUDE DES EFFETS ÉLECTROSTATIQUES SUR LE MÉCANISME D'ACTION CATALYTIQUE DE LA PHOSPHATASE ALCALINE INTESTINALE DE VEAU

1965 ◽  
Vol 43 (8) ◽  
pp. 2222-2235 ◽  
Author(s):  
Michel Lazdunski ◽  
Jacques Brouillard ◽  
Ludovic Ouellet
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Maximum Activity ◽  
Enzyme Molecule ◽  
High Substrate Concentration ◽  
Nitrophenyl Phosphate ◽  
Phosphatase Alcaline ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Activated Complex

The influence of dioxane and ethanol on the rate of hydrolysis of p-nitrophenyl phosphate in the presence of an intestinal alcaline phosphatase can be interpreted as a dielectric constant effect, at high substrate concentration. The dielectric constant effect is a function of the pH of the medium and is maximum around pH 9.4 at 25 °C and pH 9.0 at 15 °C. An interpretation suggesting that the change in diameter of the enzyme molecule becoming an activated complex is minimum at a pH of maximum activity is proposed. The same model can take into account the influence of the ionic strength on the same reaction.

Mechanistic Information from the Effect of Pressure on the Kinetics of Hydrolysis of Iodopentaaquochromium(III) Ion

1975 ◽  
Vol 53 (24) ◽  
pp. 3697-3701 ◽  
Author(s):  
Milton Cornelius Weekes ◽  
Thomas Wilson Swaddle
Keyword(s):  
Ionic Strength ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Aqueous Hclo ◽  
Conjugate Base

The rate of hydrolysis of iodopentaaquochromium(III) ion has been measured as a function of pressure (0.1 to 250 MPa) and hydrogen ion concentration (0.1 to 1.0 mol kg−1) at 298.2 K and ionic strength 1.0 mol kg−1 (aqueous HClO4–LiClO4). The volumes of activation for the acid independent and inversely acid dependent hydrolysis pathways are −5.4 ± 0.5 and −1.6 ± 0.3 cm3 mol−1 respectively, and are not detectably pressure-dependent. Consideration of these values, together with the molar volume change of −3.3 ± 0.3 cm3 mol−1 determined dilatometrically for the completed hydrolysis reaction, indicates that the mechanisms of the two pathways are associative interchange (Ia) and dissociative conjugate base (Dcb) respectively.

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.

THE EFFECT ON REACTION RATES CAUSED BY THE SUBSTITUTION OF C14 FOR C12: I. THE ALKALINE HYDROLYSIS OF CARBOXYL-LABELED ETHYL BENZOATE

1949 ◽  
Vol 27b (10) ◽  
pp. 807-812 ◽  
Author(s):  
William H. Stevens ◽  
Richard W. Attree
Keyword(s):  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Room Temperature ◽  
Reaction Rates ◽  
Ethyl Benzoate ◽  
Hydrolysis Rate ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

A study of the alkaline hydrolysis of C14 carboxyl-labeled ethyl benzoate has shown that the substitution of C14 for C12 changes the rate of hydrolysis of the ester. Ester molecules containing C14 hydrolyze at a slower rate than normal ester molecules. The ratio of the hydrolysis rate constants at room temperature has been found to be 0.86 ± 0.016.

INFLUENCE OF CALCIUM IONS ON THE MYOSIN-CATALYZED HYDROLYSIS OF ADENOSINE TRIPHOSPHATE

1958 ◽  
Vol 36 (6) ◽  
pp. 896-901 ◽  
Author(s):  
G. E. Pelletier ◽  
Ludovic Ouellet
Keyword(s):  
Reaction Mechanism ◽  
Stability Constants ◽  
Adenosine Triphosphate ◽  
Calcium Ions ◽  
Equilibrium Constants ◽  
Hydrogen Ion ◽  
Ion Concentrations ◽  
Calcium Complexes ◽  
Hydrolysis Of

The activation of the myosin-catalyzed hydrolysis of adenosine triphosphate by calcium ions has been studied at pH 7.5 over a range of temperature extending from 3° to 25 °C. There is evidence that the activation is due to the equilibrium formation of a complex between adenosine triphosphate and calcium ions.From such a reaction mechanism, values of equilibrium constants are reported for the binding of adenosine triphosphate to the myosin in the presence and in the absence of calcium ions, together with stability constants for the calcium complexes of both the adenosine triphosphate and the myosin – adenosine triphosphate. The influence of hydrogen-ion concentrations on these constants is indicated.

scholarly journals THE RÔLE OF THE ACTIVITY COEFFICIENT OF THE HYDROGEN ION IN THE HYDROLYSIS OF GELATIN

1921 ◽  
Vol 3 (6) ◽  
pp. 715-742 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Hydrogen Ion ◽  
Ion Concentration ◽  
Alkaline Solutions ◽  
Solution Ph ◽  
Hydrogen Electrode ◽  
Hydrogen Ion Concentration ◽  
Monomolecular Reaction ◽  
Hydroxyl Ion ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

1. The hydrolysis of gelatin at a constant hydrogen ion concentration follows the course of a monomolecular reaction for about one-third of the reaction. 2. If the hydrogen ion concentration is not kept constant the amount of hydrolysis in certain ranges of acidity is proportional to the square root of the time (Schütz's rule). 3. The velocity of hydrolysis in strongly acid solution (pH less than 2.0) is directly proportional to the hydrogen ion concentration as determined by the hydrogen electrode i.e., the "activity;" it is not proportional to the hydrogen ion concentration as determined by the conductivity ratio. 4. The addition of neutral salts increases the velocity of hydrolysis and the hydrogen ion concentration (as determined by the hydrogen electrode) to approximately the same extent. 5. The velocity in strongly alkaline solutions (pH greater than 10) is directly proportional to the hydroxyl ion concentration. 6. Between pH 2.0 and pH 10.0 the rate of hydrolysis is approximately constant and very much greater than would be calculated from the hydrogen and hydroxyl ion concentration. This may be roughly accounted for by the assumption that the uncombined gelatin hydrolyzes much more rapidly than the gelatin salt.

Lattice imaging and pore structure of β ferric oxyhydroxide

1978 ◽  
Vol 36 (1) ◽  
pp. 264-265
Author(s):  
T. Baird ◽  
J.R. Fryer ◽  
S.T. Galbraith
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bulk Material ◽  
Model Structure ◽  
Bulk Crystals ◽  
Lattice Imaging ◽  
Thin Sections ◽  
Ferric Oxyhydroxide ◽  
Resolution Electron ◽  
Hydrolysis Of

Introduction Previously we had suggested (l) that the striations observed in the pod shaped crystals of β FeOOH were an artefact of imaging in the electron microscope. Contrary to this adsorption measurements on bulk material had indicated the presence of some porosity and Gallagher (2) had proposed a model structure - based on the hollandite structure - showing the hollandite rods forming the sides of 30Å pores running the length of the crystal. Low resolution electron microscopy by Watson (3) on sectioned crystals embedded in methylmethacrylate had tended to support the existence of such pores.We have applied modern high resolution techniques to the bulk crystals and thin sections of them without confirming these earlier postulatesExperimental β FeOOH was prepared by room temperature hydrolysis of 0.01M solutions of FeCl3.6H2O, The precipitate was washed, dried in air, and embedded in Scandiplast resin. The sections were out on an LKB III Ultramicrotome to a thickness of about 500Å.

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