Michaelis-Menten kinetics for

On the other hand, the macrolides showed unusual enzymatic reactivity. Lipase PF-catalyzed polymerization of the macrolides proceeded much faster than that of 8-CL. The lipase-catalyzed polymerizability of lactones was quantitatively evaluated by Michaelis-Menten kinetics. For all monomers, linearity was observed in the Hanes-Woolf plot, indicating that the polymerization followed Michaehs-Menten kinetics. The V, (iaotone) and K,ax(iaotone)/ m(iaotone) values increased with the ring size of lactone, whereas the A (iactone) values scarcely changed. These data imply that the enzymatic polymerizability increased as a function of the ring size, and the large enzymatic polymerizability is governed mainly by the reachon rate hut not to the binding abilities, i.e., the reaction process of... 

Quite often the asymptotic behavior of the model can aid us in determining sufficiently good initial guesses. For example, let us consider the Michaelis-Menten kinetics for enzyme catalyzed reactions,... 

Yu, XZ, Gu J-D (2006) Uptake, metabolism, and toxicity of methyl ter/-butyl ether (MTBE) in weeping willows. J Hardz Mat B137 1417-1423 Yu, XZ, Gu J-D (2007a) Differences in Michaelis-Menten kinetics for different cultivars of maize during cyanide removal. Ecotoxicol Environ Saf 67 254-259... 

Bosma et al. [1] have proposed including the details of extracellular substrate transport in the calculation of whole-cell Michaelis-Menten kinetics. For the situation of a quasi-steady-state (i.e. when the transport flux and the rate of degradation of the substrate are equal) the consumption of substrate by a microorganism is represented as a function of the distant, and effectively unavailable, substrate concentration ca ... 

The overall influence of ATP on the rate V (ATP) is measured by a saturation parameter C (—oo, 1]. Note that, when using Eq. (139) as an explicit rate equation, the saturation parameter implicitly specifies a minimal Hill coefficient min > C necessary to allow for the reverse transformation of the parameters. The interval 6 [0,1] corresponds to conventional Michaelis Menten kinetics. For = 0, ATP has no net influence on the reactions, either due to complete saturation of a Michaelis Menten term or, equivalently, due to an exact compensation of the activation by ATP as a substrate by its simultaneous effect as an inhibitor. For < 0, the inhibition by ATP supersedes the activation of the reaction by its substrate ATP. 

Crude and three diethyl ether extracted, acetone treated, fractions were isolated from large-scale cultures of Gambierdiscus toxicus. Crude extracts at. 04 mg/ml inhibited the histamine contraction response in smooth muscle of the guinea pig ileum. Three semi-purified fractions at 5 ng/ml, effectively inhibited the guinea pig ileum preparation. Two of these fractions followed Michaelis-Menten kinetics for a competitive inhibition. The third fraction inhibited in a non-reversible manner. This study has established the presence of three lipid extracted toxins in toxicus, outlined a method for their assay in small quantities, and identified at least two of the effects of these toxic extracts in animals. 

A simple example is the so-called Michaelis-Menten kinetics for enzymatic reactions A + E +C->B + E, which, when the pseudo-steady-state hypothesis is invoked, gives for the concentration of A, for instance, a,... 

If non-Michaelis-Menten kinetics for all P450 enzymes are a result of multiple substrates binding to the enzyme, then the reaction kinetics for the binding of two substrates to an active site can be complicated. A number of analyses of... 

Feedback to the pituitary is modeled following Michaelis-Menten kinetics for an allosteric inhibited reaction which gives ... 

The Henri-Michaelis-Menten equation describes the curve obtained when initial velocity is plotted versus substrate concentration. The curve shown in Figure 4-7 is a right rectangular hyperbola with limits of and - K . The curvature is fixed regardless of the values of and V mxx- Consequently, the ratio of substrate concentrations for any two fractions of Vj m is constant for all enzymes that obey Henri-Michaelis-Menten kinetics. For example, the ratio of substrate required for 90% of Vmat to the substrate required for... 

In this case Michaelis-Menten double substrate kinetics is chosen (compare to Eq. (45)). The system involving D-HicDH with DHPP and PEG-NADH as substrates exhibits Michaelis-Menten kinetics for both substrates and competitive product inhibition by PEG-NAD+. FDH also shows Michaelis-Menten kinetics for both substrates formate and PEG-NAD+ and competitive product inhibition by PEG-... 

As with competitive inhibition, two additional reaction steps are addr the Michaelis-Menten kinetics for uncompetitive inhibition as shown in i tion Steps 4 and 5. 

In section 9.5.3 the arbitrary kinetics for the slab geometry was considered. In this section we will use Michaelis-Menten kinetics for describing immobilized enzymes and spherical particles following the nomenclature and approaches frequently encounted in the literature on bioreaction engineering for instance in the treatment provided by J.E. Bailey and D.F.011is presented here with the details of the derivation. 

A final test of the intracellular fluxes determined by metabolite balancing was provided through comparison with the predictions of a first-order kinetic model describing the oxidation of pulsed [ C]-indene to all detectable indene derivatives in steady state cells. Assuming Michaelis-Menten kinetics for a typical reaction depicted in Fig. 4, the rate of labeled metabolite conversion by that reaction can be expressed as... 

The enzyme shows Michaelis-Menten kinetics for the amino-group donor glutamine, chorismate, and the cofactor Mg (K values respectively... 

Michaelis-Menten Kinetics for Oxygen Transfer Reactions - Quo Vadis ... 

Conversely, Errel et al. (1973) and Stewart and Rhodes (1977a) found normal Michaelis-Menten kinetics for all substrates for the enzymes from safflower cotyledons andL. minor, respectively. Garland and Dennis (1977) found normal kinetics for all substrates in the presence of 1 mM CaCU, except for substrate inhibition at high substrate concentrations and activation at high NAD concentrations, with the pea stem enzyme. 

The theoretical description of electrocatalysis that takes into account electron and ion transfer and the transport process, the permeations of the substrates, and their combined involvement in the control over the overall kinetics has been elaborated by Albeiy and Hillman [312,313,373] and by Andrieux and Saveant [315], and a good summary can be found in [314]. Practically all of the possible cases have been considered, including Michaelis-Menten kinetics for enzyme catalysis. Inhibition, saturation, complex mediation, etc., have also been treated. The different situations have also been represented in diagrams. Based on the theoretical models, the respective forms of the Koutecky-Levich eqrration have been obtained, which make analyzing the resirlts of voltarrrmetry on stationary artd rotating disc electrodes a straightforward task. 

Discuss the three-state Michaelis—Menten kinetics for single enzyme in a steady state. 

This is the simplest mechanism leading to Michaelis-Menten kinetics, but many other mechanisms also do so. To investigate mechanisms in more detail it is necessary to use special techniques for studying very rapid reactions, such as the stopped-flow and temperature-jump methods (Section I). Various factors give deviations from Michaelis-Menten kinetics. For example, sometimes the complex ES adds on an additional substrate molecule to give ES2 if this does not react as rapidly as ES there is a falling off of the rate at higher substrate concentrations. 

The rate of biomass production, i.e., the increase in the number of cells during the exponential growth phase, is described by the empirical Monod-kinetics, which are shaped after the Michaelis-Menten kinetics for enzymatic reactions ... 

The ATP is degraded at the endothelial surface by enzymes (ectonucleotidases) to form adenosine diphosphate (ADP). The Michaelis-Menten kinetics for this reaction have been determined by Gordon et al. [7] using cultured porcine aortic endothelial cells fcm = 249 /xM, Vmax = 22 nmol/min/10 cells. Vinax can be converted to a molar flux by using a typical endothelial cell surface density of 1.2 x 10 cells/cm, with the result that the pseudo-first order rate constant (Equation 9.3) is = 1.77 x 10 cm/sec. Assuming a diffusivity of 5.0 x 10 cm /sec for ATP [8], and a vessel diameter of 5 mm, we find... 

The enzyme preparation used for these studies was purified approximately 40 fold from human placenta and assayed as previously described (Holmes, et al., 1973). In the absence of purine ribonucleotides human amidotransferase exhibits Michaelis-Menten kinetics for the substrate PP-ribose-P. However, the inclusion of purine ribonucleotides in the assay system results in a qualitative change in the kinetics from a hyperbolic to a sigmoidal function. The result is a marked inhibition of amidotransferase by purine ribonucleotides at physiological concentrations of PP-ribose-P. On the other hand the inhibition produced by purine ribonucleotides... 

Again, obe5dng the cited reaction kinetics to Michaelis-Menten kinetics for formation of intermediate complexes (1/rate vs. 1/[S] plots), may be considered indirect evidence to confirm the formation of some intermediate complexes (C ) between the attacked chromic acid (Ox) and the protonated substrates (SH ) as follows ... 

Rubinow, S.I Lebowitz, J. L. (1970). Time-dependent michaelis-menten kinetics for an enzyme-substrate-inhibitor system. J. Am. Chem. Soc. 92, 3888-3893. 

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