scholarly journals Factors like Dilution and Mixing Influence Enzymatic Reactions

2020 ◽  
Vol 19 (4) ◽  
Author(s):  
Mahin Basha Syed ◽  
Venkatanagraraju Erumalla
Keyword(s):  
Enzyme Activity ◽  
Substrate Concentration ◽  
Enzymatic Reaction ◽  
Enzyme Reaction ◽  
Enzyme Concentration ◽  
Enzymatic Reactions ◽  
First Report ◽  
Enzyme Substrate ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Enzyme-catalyzed reactions were influenced by many factors. The enzyme reacts with the substrate and converts it into products. Enzymes are influenced by temperature, pH, enzyme concentration, and substrate concentration. This paper evaluates the hypothesis of factors that may influence enzyme activity. Two more factors that affects enzyme activity are dilution and mixing. In enzyme-substrate reactions, the small amount of dilution and mixing will not affect the enzyme activity. Dilution and mixing do not slowdowns the enzyme reaction but it enhances the enzymatic reaction up to a certain limit. Increase in dilution results in less interaction of enzyme substrate, which causes a decrease in the rate of reactions. To the best of our knowledge, this is the first report to shows that, factors like mixing and dilution also affect enzyme and substrate reactions.

THEORY OF THE TRANSIENT PHASE IN AN ENZYME SYSTEM INVOLVING TWO ENZYME-SUBSTRATE COMPLEXES: THE CASE OF THE FORMATION OF PRODUCTS FROM THE FIRST COMPLEX

1959 ◽  
Vol 37 (4) ◽  
pp. 737-743 ◽  
Author(s):  
Ludovic Ouellet ◽  
James A. Stewart
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Active Site ◽  
Substrate Concentration ◽  
Enzyme System ◽  
Kinetic Scheme ◽  
Enzyme Concentration ◽  
Theoretical Treatment ◽  
Transient Phase ◽  
Enzyme Substrate

A theoretical treatment is worked out for the kinetic scheme[Formula: see text]in which the concentration of P1 is followed. The steady-state and transient phase equations are obtained subject to the condition that the substrate concentration is greatly in excess of the enzyme concentration. The conditions under which evidence in favor of this mechanism can be obtained from experimental data are discussed. Under certain conditions, the weight of the enzyme corresponding to one active site can be determined. Methods for the evaluation of the different constants are described.

Organophosphorus pesticides stress deranged kinetic values of a few midgut carbohydrases of naiad of Trithemis aurora (burm.) (Odonata: Libellulidae)

2016 ◽  
Vol 1 (02) ◽  
pp. 155-160
Author(s):  
Shekhar Chand
Keyword(s):  
Substrate Concentration ◽  
Initial Velocity ◽  
Ph Value ◽  
Organophosphorus Pesticides ◽  
Enzymatic Reaction ◽  
Organophosphorus Pesticide ◽  
Enzymatic Reactions ◽  
Reaction Velocity ◽  
Straight Line ◽  
Maximum Reaction

The 40 Hrs. treatment of last instar naiad of Trithemis aurora (Burm.) in Chlorphyriphos and Quinalphos pesticides concentrations (LC50 = 5.12 ×10-7 ppm and 7.6 × 10-8 ppm) has shown significant variations in the enzyme kinetic parameters and arrested the enzymatic activity in the midgut tissue of last instar naiad of T. aurora causing deleterious effect on various carbohydrases at standard temp. and pH value. The midgut amylase ( μ and β amylase) showed the change in the velocity of enzymatic reaction under LC50 conc. of chlorpyriphos. The data of initial velocity and substrate concentration were processed to achieve their reciprocal values. These values were plotted and a characteristic Lineweaver Burke straight line was observed from the graph and values of maximum reaction velocity (Vmax) and Michaelis Menten constants (km) were assessed. The present organophosphorus pesticide showed an inhibitory impact on midgut amylase reaction velocity. The double reciprocal plot of initial velocity and substrate concentration after exposing the enzyme under LC50 conc. of chlorphyriphos resulted in varied Vmax and Km. values. These carbohydrase on treatment with LC50 conc. of chlorphyriphos showed an inhibitory change in the reaction velocity. The 1/V and 1/S values were plotted to achieve a characteristic Lineweaver – Burke pattern of Vmax and km values obtained as 5.0 × 10-2 [M] and 2.0 under LC50 chlorphyriphos stress for α amylase. The km and Vmax values were obtained from 0.625 × 10-3 [M] to 1.25 × 10-2 [M] for various other midgut carbohydrases with Vmax value obtained from 0.28 to 5.0 under chlorpyriphos stress. The Quinalphos inhibited the enzymatic efficiencies of various carbohydrases severely and changed Km and Vmax values were found under the pesticidal stress and found as potent uncompetitive inhibitor for enzymes as values compared to the controlled enzymatic reactions by deranging the kinetic values. The Km values determined as on 1/V and 1/S basis found deranged from 1.66 × 10-3 [M] to 10 × 10-2 [M]. The Vmax values were found in a range of 0.41 to 3.3 under LC50 Quinalphos stress for midgut hydrolases. The analysis of enzymec kinetic values revealed the great inhibitory and deranged activities of various carbohydrases under both the pesticide constrain. The present toxicants were found to change the enzymatic velocity negatively. The LC50 concentrations of these toxicants were sufficient to inhibit the activity of present hydrolases as α and β amylase, α glucosidase, α galactosidase, β galactosidase, β frictosidase and α trehalase obtaining a meaningful Lineweaver – Burke line of plotted reciprocals of data of reaction velocity and substrate concentration.

scholarly journals Ionic liquids as (co)solvents for enzymatic reactions

2006 ◽  
Vol 12 (3) ◽  
pp. 181-186 ◽  
Author(s):  
Muzafera Paljevac ◽  
Maja Habulin ◽  
Zeljko Knez
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Immobilized Lipase ◽  
Rhizomucor Miehei ◽  
Reaction Rates ◽  
Synthetic Activity ◽  
Enzymatic Reactions ◽  
Lipozyme Rm Im ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Ionic liquids are low melting point salts that represent an exciting new class of reaction solvents. Many reactions show advantages when carried out in ionic liquids, either with regard to enhanced reaction rates, improved selectivity, or easier reuse of catalysts. To ascertain the influence of ionic liquids on the enzyme activity, three different ionic liquids 1-butyl-3-methylimidazolium chloride ([bmim] [CI]) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) were synthesized and investigated as potential media for the hydrolysis of carboxymethyl cellulose, catalyzed by non-immobilized cellulase from Humicola insolens (Celluzyme 0,7T) and for ester synthesis, catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM IM). Enzyme-catalyzed reactions were performed in a batch stirred reactor at atmospheric pressure. Celluzyme 0,7T showed better activity in hydrophobic ionic liquid ([bmim] [PF6]), as compared to hydrophilic ionic liquid ([bmim] [BF4]). In the case of Lipozyme RM IM, the synthetic activity of the enzyme was strongly reduced by incubating the enzyme in ionic liquids.

scholarly journals The Origins of Enzyme Catalysis and Reactivity: Further Assessments

2021 ◽  
pp. 38-47
Author(s):  
Sosale Chandrasekhar
Keyword(s):  
Transition State ◽  
Transition State Theory ◽  
Covalent Binding ◽  
State Theory ◽  
Complex Case ◽  
Enzyme Substrate ◽  
Catalyzed Reactions ◽  
Covalently Linked ◽  
Enzyme Catalyzed Reactions ◽  
Covalent Intermediate

Alternatives to conventional mechanisms of enzyme catalyzed reactions, although within the ambit of transition state theory, are explored herein. This is driven by reports of a growing number of enzymes forming covalently linked enzyme-substrate intermediates, which clearly deviate from the conventional Michaelis-complex mechanism. It is argued that the formation of the covalent intermediates can be accommodated within the framework of transition state theory and the original Pauling hypothesis. This also obviates the need to invoke intramolecular reactivity to explain enzymic accelerations. Thus, the covalent binding of a substrate distorted towards the transition state, with the binding being fully manifested in the ensuing transition state, would conform to the traditional endergonic pre-equilibrium mechanism. Intriguingly, an alternative exergonic formation of the covalent intermediate would also lead to catalysis: in this case, any of the three steps–covalent binding, turnover or product release–can be rate limiting. Although the exergonic mode has been dismissed previously as leading to a “thermodynamic pit” (Michaelis complex case), this view now needs to be reassessed as it seems inaccurate. Therefore, it remains for the enzyme to stabilize the various transition states via the multifarious mechanisms available to it. The Pauling hypothesis remains vindicated.

Effect of Prostaglandins (E2 and A2) on the Enzymatic Reaction of Human Renin in Isolated Homologous System and with Added Normal and Hypertensive Plasma

1974 ◽  
Vol 48 (s2) ◽  
pp. 307s-309s
Author(s):  
P. Eggena ◽  
J. Barrett ◽  
M. Sambhi
Keyword(s):  
Prostaglandin E2 ◽  
Substrate Concentration ◽  
Enzymatic Reaction ◽  
Product Formation ◽  
Inhibitory Effect ◽  
Renin Substrate ◽  
Enzyme Substrate ◽  
Normal Plasma ◽  
Human Renin ◽  
Prostaglandin A2

1. Prostaglandin E2 significantly inhibits the renin reaction in whole plasma as well as in the isolated system of semi-purified human renin and human renin substrate. The inhibitory effect of prostaglandin A2 was less marked in whole plasma and absent in the isolated system. 2. The inhibitory effect of prostaglandin E2 was more marked in normal than hypertensive plasma and was maximal at the lowest concentration used. In hypertensive plasma the maximal inhibitory effect was achieved at tenfold higher concentrations. 3. In normal plasma prostaglandin E2 does not affect the rate of product formation (k5 = k6), but inhibits the overall renin reaction by decreasing the total amount of available enzyme-substrate and enzyme-substrate modifier complex (K2K3). 4. In hypertensive plasma prostaglandin E2 acts as a potential accelerator of the rate of product formation (k6k5). In the range of substrate concentration employed, the apparent inhibitory effect is explained by an even greater lack of available complex (K2K3). This behaviour in hypertensive plasma is consistent with the presence of an additional modifier (? activator).

scholarly journals Kinetics of an enzyme reaction in which both the enzyme-substrate complex and the product are unstable or only the product is unstable

1994 ◽  
Vol 303 (2) ◽  
pp. 435-440 ◽  
Author(s):  
C Garrido-del Solo ◽  
F García-Cánovas ◽  
B H Havsteen ◽  
E Valero ◽  
R Varón
Keyword(s):  
Computer Simulation ◽  
Data Analysis ◽  
Kinetic Data ◽  
Enzyme Reaction ◽  
Enzyme Concentration ◽  
Substrate Complex ◽  
Use Of Data ◽  
Enzyme Substrate ◽  
Experimental Errors ◽  
Kinetics Of

A kinetic analysis of the Michaelis-Menten mechanism has been made for the case in which both the enzyme-substrate complex and the product are unstable or only the product is unstable, either spontaneously or as the result of the addition of a reagent. This analysis allows the derivation of equations which under conditions of limiting enzyme concentration relate the concentration of all of the species to the time. A kinetic data analysis is suggested, which leads to the evaluation of the kinetic parameters involved in the reaction. The analysis is based on the equation which describes the formation of products with time and one's experimental progress curves. We demonstrate the method numerically by computer simulation of the reaction with added experimental errors and experimentally by the use of data from the kinetic study of the action of tyrosinase on dopamine.

scholarly journals PRODUKSI DAN PENENTUAN KONDISI OPTIMUM ENZIM XILANASE Bacillus amyloliquefaciens FUKUMOTO PADA SUBSTRAT XILAN JERAMI

2015 ◽  
Vol 2 (1) ◽  
pp. 74
Author(s):  
Widiyanti Sekatresna ◽  
Abdi Dharma ◽  
Periadnadi
Keyword(s):  
Enzyme Activity ◽  
Rice Straw ◽  
Incubation Time ◽  
Substrate Concentration ◽  
Bacillus Amyloliquefaciens ◽  
Specific Activity ◽  
Enzymatic Reaction ◽  
Optimal Conditions ◽  
Enzyme Specific Activity

 ABSTRACT The production and determination of  optimal condition of xylanase produced by Bacillus amyloliquefaciens on rice straw xylan were investigated in this study. The parameters to be observed were optimal conditions of pH, temperature, substrate concentration and incubation time. Xilanase activity was determined by measuring the amount of reducing sugar formed in the enzymatic reaction based on Somogyi Nelson method. Optimal conditions needed for the production of xylanase were at pH 7, temperature 27°C and six days of incubation time. While optimal conditions of xylanase action were reached at pH 8.2, temperature 45°C, substrate concentration 3.5%(w/w) and 15 minutes of incubation time with enzyme activity and enzyme specific activity of 1.285 U/mL and 0.738 U/mg respectively. As a comparison, xylanase was also produced on pure xylan  (birchwood), enzyme activity and enzyme specific activity obtained were 2.701 U/mL and 1.658 U/mg respectively. Cellulase content in enzyme produced on rice straw xilan showed the enzyme activity of 0.094 U/mL.  Keywords : xylanase, Bacillus amyloliquefaciens, rice straw xilan

scholarly journals One-step catalytic asymmetric synthesis of all-syn deoxypropionate motif from propylene: Total synthesis of (2R,4R,6R,8R)-2,4,6,8-tetramethyldecanoic acid

2016 ◽  
Vol 113 (11) ◽  
pp. 2857-2861 ◽  
Author(s):  
Yusuke Ota ◽  
Toshiki Murayama ◽  
Kyoko Nozaki
Keyword(s):  
Building Blocks ◽  
Single Step ◽  
Enzymatic Reactions ◽  
Stereogenic Centers ◽  
Complex Building ◽  
One Step ◽  
Simple Molecules ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions ◽  
Major Acid

In nature, many complex structures are assembled from simple molecules by a series of tailored enzyme-catalyzed reactions. One representative example is the deoxypropionate motif, an alternately methylated alkyl chain containing multiple stereogenic centers, which is biosynthesized by a series of enzymatic reactions from simple building blocks. In organic synthesis, however, the majority of the reported routes require the syntheses of complex building blocks. Furthermore, multistep reactions with individual purifications are required at each elongation. Here we show the construction of the deoxypropionate structure from propylene in a single step to achieve a three-step synthesis of (2R,4R,6R,8R)-2,4,6,8-tetramethyldecanoic acid, a major acid component of a preen-gland wax of the graylag goose. To realize this strategy, we focused on the coordinative chain transfer polymerization and optimized the reaction condition to afford a stereo-controlled oligomer, which is contrastive to the other synthetic strategies developed to date that require 3–6 steps per unit, with unavoidable byproduct generation. Furthermore, multiple oligomers with different number of deoxypropionate units were isolated from one batch, showing application to the construction of library. Our strategy opens the door for facile synthetic routes toward other natural products that share the deoxypropionate motif.

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