scholarly journals THE EFFECT OF THE CONCENTRATION OF ENZYME ON THE RATE OF DIGESTION OF PROTEINS BY PEPSIN

1920 ◽  
Vol 2 (5) ◽  
pp. 471-498 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Differential Equation ◽  
Integral Equation ◽  
Ethyl Acetate ◽  
Total Concentration ◽  
Enzyme Concentration ◽  
Mass Action ◽  
Law Of Mass Action ◽  
The One ◽  
Relative Change ◽  
Hydrolysis Of

1. In certain cases the rate of digestion of proteins by pepsin is not proportional to the total concentration of pepsin. 2. It is suggested that this is due to the fact that the enzyme in solution is in equilibrium with another substance (called peptone for convenience) and that the equilibrium is quantitatively expressed by the law of mass action, according to the following equation. See PDF for Equation It is assumed that only the uncombined pepsin affects the hydrolysis of the protein. 3. The hypothesis has been put in the form of a differential equation and found to agree quantitatively with the experimental results when the concentration of pepsin, peptone, or both is varied. 4. Pepsin inactivated with alkali enters the equilibrium to the same extent as active pepsin. 5. Under certain conditions (concentration of peptone large with respect to pepsin, and concentration of substrate relatively constant) the relative change in the amount of active pepsin is inversely proportional to the concentration of peptone and the equation simplifies to Schütz's rule. 6. An integral equation is obtained which holds for the entire course of the digestion (except for the first few minutes) with varying enzyme concentration. This equation is identical in form with the one derived by Arrhenius for the action of ammonia on ethyl acetate. 7. It is pointed out that there are many analogies between the action of pepsin on albumin solutions and the action of toxins on an organism.

scholarly journals THE INFLUENCE OF THE SUBSTRATE CONCENTRATION ON THE RATE OF HYDROLYSIS OF PROTEINS BY PEPSIN

1920 ◽  
Vol 2 (6) ◽  
pp. 595-611 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Relative Rate ◽  
Total Concentration ◽  
Mass Action ◽  
Protein Solutions ◽  
Law Of Mass Action ◽  
Active Mass ◽  
Homogeneous Solutions ◽  
Rate Of Hydrolysis ◽  
The Law ◽  
Hydrolysis Of

1. It is pointed out that the apparent exceptions to the law of mass action found in enzyme reactions may be found in catalytic reactions in strictly homogeneous solutions. 2. These deviations in the rate of reaction from the law of mass action may be explained by the hypothesis that the active mass of the reacting substances is not directly proportional to the total concentration of substance taken. 3. In support of this suggestion it is shown that for any given concentration of pepsin the relative rate of digestion of concentrated and of dilute protein solutions is always the same. If the rate of digestion depended on the saturation of the surface of the enzyme by substrate the relative rate of digestion of concentrated protein solutions should increase more rapidly with the concentration of enzyme than that of dilute solutions. This was found not to be true, even when the enzyme could not be considered saturated in the dilute protein solutions. 4. The rate of digestion and the conductivity of egg albumin solutions of different concentration were found to be approximately proportional at the same pH. This agrees with the hypothesis first expressed by Pauli that the ionized protein is largely or entirely the form which is attacked by the enzyme. 5. The rate of digestion is diminished by a very large increase in the viscosity of the protein solution. This effect is probably a mechanical one due to the retardation of the diffusion of the enzyme.

scholarly journals DOES THE KINETICS OF TRYPSIN DIGESTION DEPEND ON THE FORMATION OF A COMPOUND BETWEEN ENZYME AND SUBSTRATE

1922 ◽  
Vol 4 (5) ◽  
pp. 487-509 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Experimental Evidence ◽  
Substrate Concentration ◽  
Relative Velocity ◽  
Mass Action ◽  
Law Of Mass Action ◽  
Rate Of Hydrolysis ◽  
Gelatin Concentration ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Substrate Concentrations

1. The velocity of hydrolysis of gelatin by trypsin increases more slowly than the gelatin concentration and finally becomes nearly independent of the gelatin concentration. The relative velocity of hydrolysis of any two substrate concentrations is independent of the quantity of enzyme used to make the comparison. 2. The rate of hydrolysis is independent of the viscosity of the solution. 3. The percentage retardation of the rate of hydrolysis by inhibiting substances, is independent of the substrate concentration. 4. There is experimental evidence that the enzyme and inhibiting substance are combined to form a widely dissociated compound. 5. If the substrate were also combined with the enzyme, an increase in the substrate concentration should affect the equilibrium between the enzyme and the inhibiting substance. This is not the case. 6. The rate of digestion of a mixture of casein and gelatin is equal to the sum of the rates of hydrolysis of the two substances alone, as it should be if the rate is proportional to the concentration of free enzyme. This contradicts the saturation hypothesis. 7. If the reaction is followed by determining directly the change in the substrate concentration, it is found that this change agrees with the law of mass action; i.e., the rate of digestion is proportional to the substrate concentration.

scholarly journals THE KINETICS OF ENZYME REACTIONS: SCHÜTZ'S LAW

1930 ◽  
Vol 13 (3) ◽  
pp. 323-334 ◽  
Author(s):  
E. A. Moelwyn-Hughes ◽  
J. Pace ◽  
W. C. M. Lewis
Keyword(s):  
Experimental Results ◽  
Mass Action ◽  
Law Of Mass Action ◽  
Enzyme Reactions ◽  
Adsorption Theory ◽  
The Law ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Tryptic Hydrolysis ◽  
Made In

1. A review of the applicability of Schütz's Law to enzymic reactions is given. 2. The theoretical deductions of the Law, (a) on the basis of the law of mass action, (b) on the basis of the adsorption theory, are given and the significance of the assumptions made in these deductions pointed out. 3. It is shown that the true critical increment for an enzymic reaction is equal to twice the critical increment calculated from the Schütz constant ks, if the heat of decomposition of the enzyme-products complex be neglected. 4. Experiments are described on the tryptic hydrolysis of casein at 30°C. and 404C. The foregoing considerations are applied to the experimental results obtained.

scholarly journals The optimum temperature of salicin hydrolysis by enzyme action is independent of the concentrations of substrate and enzyme

1914 ◽  
Vol 87 (594) ◽  
pp. 245-254 ◽  
Keyword(s):  
Enzyme Concentration ◽  
The Other ◽  
Optimum Temperature ◽  
Constant Concentration ◽  
M 10 ◽  
The One ◽  
The Given ◽  
Hydrolysis Of ◽  
Preliminary Determination

The object of the present investigation is to ascertain the influence, if any, on the optimum temperature—temperature of greatest activity—of an enzyme, of the concentration, on the one hand, of the substrate, and, on the other, of the enzyme. The investigation, involving two variables, presents three cases for consideration, according as the concentration of the substrate and the concentration of the enzyme are varied separately or together. An account is given of the results obtained with the enzyme or enzymic function, present in sweet-almond emulsin, which hydrolyses the glucoside salicin with the production of equimolecular quantities of glucose and saligenin. A commercial specimen of Merck’s emulsin was used, while the purity of the salicin employed was ascertained by determining its melting point (200-5°) and its optical activity ([ α ] 21 D = -62·7°). The successive stages in the inquiry may be briefly summarised as follows: (1) a preliminary determination of the activity of the specimen under certain chosen conditions as regards the concentration of the substrate, the temperature, and the duration of the experiment; (2) a preliminary determination of the optimum temperature with the quantity of enzyme found capable of producing 50 per cent, hydrolysis of the substrate under the above conditions; (3) a determination of the activity curves of the enzyme at the temperature thus found, in an action of the same duration for five concentrations of the substrate M/5, M/10, M/15, M/30, and M/50; (4) a determination of the optimum temperature of the enzyme for each of the five concentrations of the substrate in presence of a constant enzyme concentration ; (5) a determination of the optimum temperature of the enzyme for each of the five concentrations of the substrate with quantities of enzyme indicated by the activity curves as capable of producing 70 per cent, hydrolysis of the substrate in the given time: (6) a determination of the optimum temperature of the enzyme for a constant concentration of the substrate in presence of different enzyme concentrations.

The Effects of Amines on the Esterase Activities of Thrombin and Thrombokinase and on Several Clotting Tests

1974 ◽  
Vol 31 (02) ◽  
pp. 309-318
Author(s):  
Phyllis S Roberts ◽  
Raphael M Ottenbrite ◽  
Patricia B Fleming ◽  
James Wigand
Keyword(s):  
Choline Chloride ◽  
Polymerization Process ◽  
Ammonium Bromide ◽  
Bovine Thrombin ◽  
One Stage ◽  
Human Proteins ◽  
Rate Of Hydrolysis ◽  
The One ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

Summary1. Choline chloride, 0.1 M (in 0.25 M Tris. HCl buffer, pH 7.4 or 8.0, 37°), doubles the rate of hydrolysis of TAME by bovine thrombokinase but has no effect on the hydrolysis of this ester by either human or bovine thrombin. Only when 1.0 M or more choline chloride is present is the hydrolysis of BAME by thrombokinase or thrombin weakly inhibited. Evidence is presented that shows that these effects are due to the quaternary amine group.2. Tetramethyl ammonium bromide or chloride has about the same effects on the hydrolysis of esters by these enzymes as does choline chloride but tetra-ethyl, -n.propyl and -n.butyl ammonium bromides (0.1 M) are stronger accelerators of the thrombokinase-TAME reaction and they also accelerate, but to a lesser degree, the thrombin-TAME reaction. In addition, they inhibit the hydrolysis of BAME by both enzymes. Their effects on these reactions, however, do not follow any regular order. The tetraethyl compound is the strongest accelerator of the thrombokinase-TAME reaction but the tetra-ethyl and -butyl compounds are the strongest accelerators of the thrombin-TAME reaction. The ethyl and propyl compounds are the best (although weak) inhibitors of the thrombokinase-BAME and the propyl compound of the thrombin-BAME reactions.3. Tetra-methyl, -ethyl, -n.propyl and -n.butyl ammonium bromides (0.01 M) inhibit the clotting of fibrinogen by thrombin (bovine and human proteins) at pH 7.4, imidazole or pH 6.1, phosphate buffers and they also inhibit, but to a lesser degree, a modified one-stage prothrombin test. In all cases the inhibition increases regularly as the size of the alkyl group increases from methyl to butyl. Only the ethyl com pound (0.025 M but not 0.01 M), however, significantly inhibits the polymerization of bovine fibrin monomers. It was concluded that inhibition of the fibrinogen-thrombin and the one-stage tests by the quaternary amines is not due to any effect of the com pounds on the polymerization process but probably due to inhibition of thrombin’s action on fibrinogen by the quaternary amines.

Enzyme-assisted Extraction for Optimized Recovery of Phenolic Bioactives from Peganum hermala Leaves Using Response Surface Methodology

2018 ◽  
Vol 17 (4) ◽  
pp. 349-354
Author(s):  
Qadir Rahman ◽  
Anwar Farooq ◽  
Amjad Gilani Mazhar ◽  
Nadeem Yaqoob Muhammad ◽  
Ahmad Mukhtar
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Enzyme Concentration ◽  
Coumaric Acid ◽  
Assisted Extraction ◽  
Pre Treatment ◽  
Optimized Conditions ◽  
Enzyme Complexes ◽  
Hydrolysis Of ◽  
Central Composite

This study investigates the effect of enzyme formulations (Zympex-014, Kemzyme dry-plus and Natuzyme) on recovery of phenolics from Peganum hermala (harmal) leaves, under optimized conditions using response surface methodology. As compared to the other enzyme complexes, the yield (34 g/100g) obtained through Zympex-014-assisted extraction was higher under optimized conditions such as time (75 min), temperature (70°C), pH (6.5) and enzyme concentration (5 g/100 g) using central composite design (CCD). Effectiveness of Zympex-014 towards hydrolysis of P. hermala leaves cell wall was examined by analyzing the control and enzyme-treated leave residues using scanning electron microscope (SEM). GC/MS characterization authenticated the presence of quercetin (1.44), gallic acid (0.23), caffeic acid (0.04), cinnamic acid (0.05), m-coumaric acid (0.23) and p-coumaric acid (0.37 μg/g) as the potent phenolics in Zympex-014 based extract. It can be concluded from the findings of the current work that pre-treatment of P. hermala leaves with Zympex-014 significantly enhanced the recovery of phenolics that supports its potential uses in the nutra-pharamaceutical industry.

scholarly journals Genetic recombination as a generalised gradient flow

2021 ◽  
Author(s):  
Frederic Alberti
Keyword(s):  
Arbitrary Number ◽  
Genetic Recombination ◽  
Reaction Network ◽  
Gradient Flow ◽  
Mass Action ◽  
Gradient System ◽  
Gradient Structure ◽  
Law Of Mass Action ◽  
Reversible Chemical Reaction ◽  
Time Partitioning

AbstractIt is well known that the classical recombination equation for two parent individuals is equivalent to the law of mass action of a strongly reversible chemical reaction network, and can thus be reformulated as a generalised gradient system. Here, this is generalised to the case of an arbitrary number of parents. Furthermore, the gradient structure of the backward-time partitioning process is investigated.

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