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Theory
Published in Allen J. Bard, Michael V. Mirkin, Scanning Electrochemical Microscopy, 2022
Michael V. Mirkin, Yixian Wang
Enzymatic reactions and the patterning of the substrate with enzymes have been subject of many SECM studies. First simulations of enzyme kinetics at the substrate were carried out by Pierce et al. [87]. A more extensive set of simulations and the analysis of limitations of the earlier treatment were presented later by Burchardt et al. [88]. The most comprehensive treatment to date is by Lefrou et al. [89] who visualized different experimental situations in the form of a zone diagram, derived analytical approximations for approach curves, and proposed strategies for the extraction of kinetic parameters from current-distance curves in the presence of large excess of enzyme substrate. A more detailed discussion of these results can be found in Chapter 10.
Enzymatic Reaction Kinetics
Published in Debabrata Das, Debayan Das, Biochemical Engineering, 2019
For a better understanding of the sensitivity and effectivity of enzyme kinetics, one must deeply understand the effect of the enzyme, product, and substrate concentration on the reaction rate. In general, a plot of different substrate concentrations versus reaction rates yields a profile depicting a parabolic increase in the reaction rate till a particular substrate concentration. From this profile, one can conclude the following: A linear variation in the reaction rate and substrate concentration is observed especially in the lower range of substrate concentration. Hence, we can infer that the substrate concentration and the reaction rate are directly proportional to each other for the lower ranges in the substrate concentration. Generally, the order of the reaction in such cases is found to be almost 1.For the cases involving a greater range of substrate concentration, the rate of reaction becomes independent of the substrate concentration. Hence, in such cases the order of the reaction tends to zero.The reaction rate reaches a maximum (vmax) after a particular substrate concentration CS,opt. Beyond CS,opt, the reaction rate remains constant irrespective of the substrate concentration.
Comparative Study of Predictive Models in Microbial-Induced Corrosion
Published in Shampa Sen, Leonid Datta, Sayak Mitra, Machine Learning and IoT, 2018
As biofilm formation in case of MIC phenomenon is essentially kicked off by the release of enzymes, as explained earlier, enzyme kinetics models are used. Enzyme kinetics encompasses the understanding on how the enzyme functions, formation of the enzyme substrate complex, and the factors effecting enzyme substrate complex. One can classify these mechanisms into: Single-substrate mechanisms.Multiple-substrate mechanisms.
The response surface methodology for optimization of Halomonas sp. C2SS100 lipase immobilization onto CaCO3 for treatment of tuna wash processing wastewater
Published in Preparative Biochemistry & Biotechnology, 2023
Marwa Khmaissa, Bilel Hadrich, Ameni Ktata, Mohamed Chamkha, Adel Sayari, Ahmed Fendri
The rate follow-up of an enzyme through the catalysis of a reaction is crucial to its improvement. During the transformation of substrates to products, every biocatalyst has its own rate phenomena. Kinetic parameters describe the catalytic performance of enzymes. We studied, the effect of immobilization on the rate of Halomonas sp. lipase catalysis. To achieve our goal, different substrate concentrations were chosen to explain enzyme kinetics, using the Michaelis–Menten equation. Therefore, the Vmax and KM deduced values were 750 µmol/min/mg; 0.34 mM for the free lipase, and 1466 µmol/min/mg; 0.35 mM after the immobilization of the enzyme when using olive oil emulsion as substrate. Moreover, the ratio of the Michaelis–Menten constants allowed the calculation of the catalytic efficiency of the free and immobilized lipase. The catalytic efficiency of immobilized enzyme was significantly higher than that of the free form indicating that the optimal reaction rate can be reached with a lower concentration of substrate. Similar results were obtained by Ozdemir Babavatan et al.[45] These authors have proved that the catalytic efficiency of a Rhizomucor miehei lipase immobilized onto Montmorillonite K-10 was 23.5-fold higher than that of the free lipase.
Michaelis–Menten kinetics as a model of doctoral supervisor–supervisee relationship
Published in International Journal of Mathematical Education in Science and Technology, 2023
Enzymes are molecules that act as catalysts (Suzuki, 2019). In fact, they increase the rate of biochemical reactions by which reacting substances are converted into new substances. According to Michaelis and Menten (1913), an intermediate complex ES is formed when the substrates S bind to a specific enzyme E. If the substrates react, the products P are released and the enzyme is free to catalyse another reaction. If the reaction does not occur, the complex can dissociate back into free enzyme and substrates. The scheme corresponding to this enzymatic transformation of substrates into products is (Johnson & Goody, 2011; Michaelis & Menten, 1913; Suzuki, 2019): in which α, β, and γ are the rate constants related to the complex formation, the complex dissociation, and the product formation, respectively. Notice that the enzyme-substrate binding is reversible, but the product generation is irreversible. The rates of change of the concentrations of E, S, ES, and P are governed by equations obtained from the law of mass action (Suzuki, 2019; Voit et al., 2015). This model, which is central in enzyme kinetics, has also been used to study, for instance, the adsorption of gaseous molecules by solid surfaces (Langmuir, 1918) and the metabolism of hydrogen producing bacteria (Chen et al., 2006).
Synthesis and characterization of a new 4-styrylpyridine based square planar copper(II) complex: exploration of phenoxazinone synthase-mimicking activity and DFT study
Published in Journal of Coordination Chemistry, 2019
Akhtaruz Zaman, Samim Khan, Basudeb Dutta, Sobhy M. Yakout, Shebl S. Ibrahim, Mohammad Hedayetullah Mir
All these enzyme kinetic plots have been used to evaluate several kinetic parameters, including turnover number (kcat) and specificity constant (kcat/KM) for phenoxazinone synthase-mimicking activity of the complex. In enzyme kinetics, turnover number (also termed as kcat) is defined as the maximum number of catalytic conversions of substrate molecules per unit of time that a single catalytic site will execute for a specific enzyme concentration. The specificity constant (also termed as kcat/KM ratio) is a measure of how efficiently a catalyst converts substrates into products. This ratio is a useful index for measuring the substrate specificity of catalyst. The higher the specificity constant, the more the enzyme prefers that substrate. Figures 5 and S2 represent the Michaelis–Menten plot, Lineweaver–Burk plot, Hanes–Woolf plot and Eadie–Hofstee plot for catalytic oxidation of OAPH in methanol and in 20% methanol, respectively. Tables 2 and S4 contain kinetic parameters for phenoxazinone synthase-mimicking activity in methanol and in 20% methanol, respectively.