Michaelis-Menten Model Of Enzyme Kinetics Research Articles

A study of nonlinear fractional-order biochemical reaction model and numerical simulations

This article depicts an approximate solution of systems of nonlinear fractional biochemical reactions for the Michaelis–Menten enzyme kinetic model arising from the enzymatic reaction process. This present work is concerned with fundamental enzyme kinetics, utilised to assess the efficacy of powerful mathematical approaches such as the homotopy perturbation method (HPM), homotopy analysis method (HAM), and homotopy analysis transform method (HATM) to get the approximate solutions of the biochemical reaction model with time-fractional derivatives. The Caputo-type fractional derivatives are explored. The proposed method is implemented to formulate a fractional differential biochemical reaction model to obtain approximate results subject to various settings of the fractional parameters with statistical validation at different stages. The comparison results reveal the complexity of the enzyme process and obtain approximate solutions to the nonlinear fractional differential biochemical reaction model.

Catechol Oxidase and SOD Mimicking by Copper(II) Complexes of Multihistidine Peptides

Copper(II) complexes of five peptide ligands containing at least three histidine residues have been tested as catalysts in catechol oxidation and superoxide dismutation. All systems exhibit considerable catechol oxidase-like activity, and the Michaelis–Menten enzyme kinetic model is applicable in all cases. Beside the Michaelis–Menten parameters, the effects of pH, catalyst and dioxygen concentration on the reaction rates are also reported. Considering the rather different sequences, the observed oxidase activity seems to be a general behavior of copper(II) complexes with multihistidine peptides. Interestingly, in all cases {Nim/2Nim,2N−} coordinated complexes are the pre-active species, the bound amide nitrogens were proposed to be an acid/base site for facilitating substrate binding. The studied copper(II)-peptide complexes are also able to effectively dismutate superoxide radical in the neutral pH range.

Biotransformation of the Flame Retardant 1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) in Vitro by Human Liver Microsomes.

The technical mixture of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH or DBE-DBCH) and the pure β-TBECH isomer were subjected to in vitro biotransformation by human liver microsomes (HLM). After 60 min of incubation, 5 potential metabolites of TBECH were identified in microsomal assays of both the TBECH mixture and β-TBECH using ultraperformance liquid chromatography-Q-Exactive Orbitrap mass spectrometry. These include mono- and dihydroxylated TBECH and mono- and dihydroxylated TriBECH as well as an α-oxidation metabolite bromo-(1,2-dibromocyclohexyl)-acetic acid. Our results indicate potential hepatic biotransformation of TBECH via cyctochrome P450-catalyzed hydroxylation, debromination, and α-oxidation. Kinetic studies revealed that the formation of monohydroxy-TBECH, dihydroxy-TBECH, and monohydroxy-TriBECH were best fitted to a Michaelis-Menten enzyme kinetic model. Respective estimated Vmax values (maximum metabolic rate) for these metabolites were 11.8 ± 4, 0.6 ± 0.1, and 10.1 ± 0.8 pmol min-1 mg protein-1 in TBECH mixture and 4992 ± 1340, 14.1 ± 4.9, and 66.1 ± 7.3 pmol min-1 mg protein-1 in β-TBECH. This indicates monohydroxy-TBECH as the major metabolite of TBECH by in vitro HLM-based assay. The estimated in vitro intrinsic clearance (Clint) of TBECH mixture was slower (P < 0.05) than that of pure β-TBECH. While the formation of monohydroxy-TBECH may reduce the bioaccumulation potential and provide a useful biomarker for monitoring TBECH exposure, further studies are required to fully understand the levels and toxicological implications of the identified metabolites.

Insight into the mechanism revealing the peroxidase mimetic catalytic activity of quaternary CuZnFeS nanocrystals: colorimetric biosensing of hydrogen peroxide and glucose.

Artificial enzyme mimetics have attracted immense interest recently because natural enzymes undergo easy denaturation under environmental conditions restricting practical usefulness. We report for the first time chalcopyrite CuZnFeS (CZIS) alloyed nanocrystals (NCs) as novel biomimetic catalysts with efficient intrinsic peroxidase-like activity. Novel peroxidase activities of CZIS NCs have been evaluated by catalytic oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). CZIS NCs demonstrate the synergistic effect of elemental composition and photoactivity towards peroxidase-like activity. The quaternary CZIS NCs show enhanced intrinsic peroxidase-like activity compared to the binary NCs with the same constituent elements. Intrinsic peroxidase-like activity has been correlated with the energy band position of CZIS NCs extracted using scanning tunneling spectroscopy and ultraviolet photoelectron spectroscopy. Kinetic analyses indicate Michaelis-Menten enzyme kinetic model catalytic behavior describing the rate of the enzymatic reaction by correlating the reaction rate with substrate concentration. Typical color reactions arising from the catalytic oxidation of TMB over CZIS NCs with H2O2 have been utilized to establish a simple and sensitive colorimetric assay for detection of H2O2 and glucose. CZIS NCs are recyclable catalysts showing high efficiency in multiple uses. Our study may open up the possibility of designing new photoactive multi-component alloyed NCs as enzyme mimetics in biotechnology applications.

Bioethanol Fermentation from Non-Treated and Pretreated Corn Stover using Aspergillus Oryzae

A comparison was studied for non-treated and pretreated corn stover with dilute alkaline peroxide and dilute acid treatment respectively for bioethanol production by simultaneous saccharification and fermentation (SSF) process in a continuous stirred batch bioreactor using fungi Aspergillus oryzae . The optimum parameters for bioethanol fermentation were: time, 48 h; pH, 6.0; temperature, 50oC; stirring speed, 35 rpm; and corn stover loading, 35 g/L. The maximum concentration of bioethanol at optimum fermentation process parameters were 0.762 g/g, 0.799 g/g and 0.819 g/g for non-treated, dilute acid and dilute alkaline peroxide pretreated corn stover respectively. Maximum yields of bioethanol were 0.399 g/L h, 0.420 g/L.h and 0.431 g/L h of corn stover at optimum parameters for non-treated, dilute acid and dilute alkaline peroxide pretreated corn stover respectively. The sp. growth rate (m) were 5.30 s −1 , 5.54 s −1 , and 5.93 s −1 and maximum sp. growth rate (m max ) were 10.60 s −1 , 11.08 s −1 and 11.86 s −1 using Monod model for non-treated, dilute acid and dilute alkaline peroxide pretreated corn stover respectively. The Monod parameter (K s ) were 33.87 g/L, 34.21 g/L and 34.85 g/L for non-treated, dilute acid and dilute alkaline peroxide pretreated corn stover respectively. The sp. enzyme activity (ν) were 1192 min −1 , 1463 min −1 and 1559 min −1 and maximum sp. growth rate (ν max ) were 2384 min −1 , 2926 min −1 and 3118 min −1 using Michaelis-Menten enzyme kinetic model for non-treated, dilute acid and dilute alkaline peroxide pretreated corn stover respectively. The Michaelis-Menten parameter (K m ) were 34.42 g/L, 34.63 g/L and 34.85 g/L for non-treated, dilute acid and dilute alkaline peroxide pretreated corn stover respectively. The first order rate constants (k) were 0.014 h −1 , 0.016 h −1 and 0.019 h −1 for non-treated, dilute acid and dilute alkaline peroxide pretreated corn stover for continuous stirred batch bioreactor respectively. DOI: http://dx.doi.org/10.3329/cerb.v16i1.6659 Chemical Engineering Research Bulletin 16(2013) 33-44

Lipase production from a novel thermo-tolerant and extreme acidophile Bacillus pumilus using palm oil as the substrate and treatment of palm oil-containing wastewater

The thermo-tolerant and extreme acidophilic microorganism Bacillus pumilus was isolated from the soil collected from a commercial edible-oil extraction industry. Optimisation of conditions for the lipase production was conducted using response surface methodology. The optimum conditions for obtaining the maximum activity (1,100 U/mL) of extremely acidic thermostable lipase were fermentation time, 96 h; pH, 1; temperature, 50 °C; and concentration of palm oil, 50 g/L. After purification, a 7.1-fold purity of lipase with specific activity of 5,173 U/mg protein was obtained. The molecular weight of the thermo-tolerant acidophilic lipase (TAL) was 55 kDa. The predominant amino acid in the TAL was glycine. The functional groups of lipase were determined by Fourier transform infrared spectroscopy. TAL exhibited enhanced activity (114 %) with dimethyl sulphoxide (20 %, v/v), and it showed a moderate activity with methanol, hexane and benzene. The optimum conditions for the treatment of palm oil in wastewater using the TAL were found to be time, 3 h; pH, 1; temperature, 50 °C with pseudo second-order kinetic constant of 1.88 × 10(-3) L mol(-1) min(-1). The Michaelis-Menten enzyme kinetic model and the nonlinear kinetic model were evaluated for the TAL. TAL established hydrolysis efficiency of 96 % for palm oil in wastewater at 50 °C.

Aza Cope Rearrangement of Propargyl Enammonium Cations Catalyzed By a Self-Assembled “Nanozyme”

The tetrahedral assembly [Ga4L6](12-) [L = N,N-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) encapsulates a variety of cations, including propargyl enammonium cations capable of undergoing the aza Cope rearrangement. For propargyl enammonium substrates that are encapsulated in the [Ga4L6](12-) assembly, rate accelerations by factors of up to 184 compared with the background reaction rate were observed. After rearrangement, the product iminium ion is released into solution and hydrolyzed, allowing for catalytic turnover. The activation parameters for the catalyzed and uncatalyzed reaction were determined, revealing that a decrease in the entropy of activation is responsible for the observed rate enhancements. The catalyzed reaction exhibits saturation kinetics: the rate data obeyed the Michaelis-Menten model of enzyme kinetics, and competitive inhibition using a nonreactive guest was demonstrated.

A review of existence criteria for parameter estimation of the Michaelis–Menten regression model

In this paper we consider the least squares (LS) and total least squares (TLS) problems for a Michaelis–Menten enzyme kinetic model f(x; a, b) = ax/(b + x), a, b > 0. In various applied research such as biochemistry, pharmacology, biology and medicine there are lots of different applications of this model. We will systematize some of our results pertaining to the existence of the LS and TLS estimate, which were proved in Hadeler et al. (Math Method Appl Sci 30:1231–1241, 2007) and Jukic et al. (J Comput Appl Math 201:230–246, 2007). Finally, we suggest a choice of good initial approximation and give one numerical example.

Total least squares fitting Michaelis–Menten enzyme kinetic model function

The Michaelis–Menten enzyme kinetic model f ( x ; a , b ) = ax / ( b + x ) , a , b > 0 , is widely used in biochemistry, pharmacology, biology and medical research. Given the data ( p i , x i , y i ) , i = 1 , … , m , m ⩾ 3 , we consider the total least squares (TLS) problem for the Michaelis–Menten model. We show that it is possible that the TLS estimate does not exist. As the main result, we show that the TLS estimate exists if the data satisfy some natural conditions. Some numerical examples are included.

Optimal Design for Goodness-of-Fit of the Michaelis–Menten Enzyme Kinetic Function

We construct efficient designs for the Michaelis–Menten enzyme kinetic model capable of checking model assumptions. An extended model called EMAX is also considered for this purpose. This model is widely used in pharmacokinetics and reduces to the Michaelis–Menten model for a specific choice of parameter settings. Our strategy is to find efficient designs for estimating the parameters in the EMAX model and at the same time test the validity of the Michaelis–Menten model against the EMAX model by maximizing a minimum of the D or D1 efficiencies taken over a range of values for the nonlinear parameters. In particular, we show that such designs are (a) efficient for estimating parameters in the EMAX model, (b) about 70% efficient for estimating parameters in the Michaelis–Menten model, (c) efficient for testing the Michaelis–Menten model against the EMAX model, and (d) robust with respect to misspecification of the unknown parameters in the nonlinear model.

Kinetic evidence for the mechanism of liquid-solid phase oxidation of alcohols

Benzyl alcohol oxidation is catalyzed by solid MnFe1.8Cu0.15Ru0.05O4 in the presence of molecular oxygen. The good compliance of oxidation kinetics with the Michaelis-Menten enzyme kinetic model evidences the oxidative dehydrogenation of benzyl alcohol via a Ru-alkoxide intermediate, which undergoes b-elimination to afford benzaldehyde.

Kinetics of kojic acid fermentation by Aspergillus flavus using different types and concentrations of carbon and nitrogen sources

Kinetics of kojic acid fermentation by Aspergillus flavus Link 44-1 using various sources of carbon [glucose, xylose, sucrose, starch, maltose, lactose or fructose] and nitrogen [NH4Cl, (NH4)2S2O8, (NH4)2NO3, yeast extract or peptone] were analyzed using models based on logistic and Luedeking–Piret equations. The highest kojic acid production (39.90 g l−1) in submerged batch fermentation was obtained when 100 g l−1 glucose was used as a carbon source. Organic nitrogen sources such as peptone and yeast extract were favorable for kojic acid production as compared to inorganic nitrogen sources. Yeast extract at 5 g l−1 was optimal. The optimal carbon to nitrogen (C/N) ratio for kojic acid fermentation was 93.3. In a resuspended cell system, the rate of glucose conversion to kojic acid by cell-bound enzymes increased with increasing glucose concentration up to 70 g l−1, suggesting that the reaction followed the Michaelis–Menten enzyme kinetic model. The value of Km and Vmax for the reaction was 18.47 g l−1 glucose and 0.154 g l−1 h−1, respectively. Journal of Industrial Microbiology & Biotechnology (2000) 25, 20–24.

The kinetics of soil acid phosphatase

The kinetics of enzyme systems in soil can reasonably be expected to be similar to those of immobilised enzymes and therefore be modified by factors not considered in the formulation of the classical Michaelis-Menten model of enzyme kinetics. Previous studies of the p-nitrophenyl phosphatase activity of soil have assumed that the system follows Michaelis-Menten kinetics. This paper reports experiments on the p-nitrophenyl phosphatase activity of a kraznozem in which the plotting of V 0, the initial rate. against V 0 [S] where [S] is the substrate concentration showed that the system, for this soil at least, does not follow Michaelis-Menten kinetics. An evaluation of the graphical techniques used in previous studies showed that the conclusion that the p-nitrophenyl phosphatase activity of soil follows Michaelis-Menten kinetics is based on doubtful premises. Experiments in which both the substrate and the product were measured spectrophotometrically at intervals throughout the hydrolysis of p-nitrophenyl phosphate by the kraznozem yielded evidence for a model of the system which is capable of accounting for the deviation from Michaelis-Menten kinetics.