Substrate inhibition kinetics

Hill GA, Robinson CW (1975) Substrate inhibition kinetics phenol degradation by pseudomonas putida. Biotechnol Bioeng 17 1599-1615... 

When the biochemical reactors are kinetically controlled, the batch bioreactors and the PFR are described by the same design equations (Equations (11.25) and (11.28)) and show a better performance than the CSTR in most cases, except for substrate inhibition kinetics. 

The shape of the performance curve for a continuous stirred-tank fermenter is dependent on the kinetic behaviour of the micro-organism used. In the case where the specific growth rate is described by the Monod kinetic equation, then the productivity versus dilution rate curve is given by equation 5.137 and has the general shape shown by the curve in Fig. 5.58. However, if the specific growth rate follows substrate inhibition kinetics and equation 5.65 is applicable then, at steady state, equation 5.131 becomes ... 

More complex kinetics that does not fit hyperbolic inhibition or activation are also possible. These cases usually involve combinations of activation or inhibition with a second component resulting from two-substrate kinetics, e.g., sigmoidal, biphasic, or substrate inhibition kinetics. An example is activation followed by inhibition. The inhibition component occurs when two substrates in the active site displaces the inhibitor. 

No particle mass transfer, substrate inhibition kinetics, differential packed bed [27]... 

The effect of reaction parameters, such as the concentrations of catalyst and olefin and the partial pressures of CO and hydrogen, on the rate of reaction has been studied at 373 K [19]. The rate varies linarly with catalyst concentration, olefin concentration, and partial pressure of hydrogen. Typical substrate-inhibited kinetics was observed with the partial pressure of carbon monoxide. Further, a rate equation to predict the observed rate data has been proposed (Eq. 5). 

Substrate Inhibition Substrate inhibition represents another example of cooperativity in enzyme kinetic reactions, but of a different profile than described to this point. With substrate inhibition kinetics, the velocity of a reaction increases (as expected for hyperbolic profiles) to an apex, however, beyond this point the velocity of the reaction decreases with increasing substrate concentrations (Fig. 4.7). 

FIGURE 4.7 Representative plot depicting substrate inhibition kinetics. 

FIGURE 4.9 Eadie-Hofstee plots useful to diagnose the type of kinetics occurring in a reaction for (a) hyperbolic (Michaelis-Menen) kinetics, (b) Sigmoidal kinetics, (c) Biphasic kinetics with no saturation of second phase, and (d) Substrate inhibition kinetics. 

Lin Y, Lu P, Tang C, Mei Q, Sandig G, Rodrigues AD, Rushmore TH, Shou M. Substrate inhibition kinetics for cytochrome P450-catalyzed reactions. Drug Metab Dispos 2001 29 368-374. 

A similar analysis than the one previously presented for simple Michaelis-Menten kinetics can be made for more complex kinetics involving reversible Michaelis-Menten reactions or product and substrate inhibition kinetics. Equations for each particular case and the corresponding boundary conditions for the case of spherical biocatalysts are (Jeison et al. 2003) ... 

Fig. 4.16 Global effectiveness factor (mean integral value) of an immobilized enzyme with uncompetitive substrate inhibition kinetics in a spherical particle as a function of bulk substrate concentration and Thiele modulus (k = 1)...

Stromme,J.H. Theodorsen, L. (1976). Gamma-glutamyltransferase Substrate inhibition, kinetic mechanism, and assay conditions. Clinical Chemistry, vol. 22, no.4, (April... 

HiU G.A., Robinson C.W. 1975. Substrate inhibition kinetics Phenol degradation by Pseudomonas putida, Biotechnol. Bioeng., 17, 1599—1615. 

The kinetics of hydroformylation of 1-octene using [Rh(COD)Cl]2 as a catalyst precursor with TPPTS as a water-soluble ligand and ethanol as a co-solvent was further studied by Deshpande et al. [15] at different pH values. The rate increased by two- to fivefold when the pH increased from 7 to 10, while the dependence of the rate was found to be linear with olefin and hydrogen concentrations at both pH values. The rate of hydroformylation was foimd to be inhibited at higher catalyst concentrations at pH 7, in contrast to linear dependence at pH 10 (Figure 5). The effect of the concentration of carbon monoxide was linear at pH 7, in contrast to the usual negative-order dependence. At pH 10, substrate-inhibited kinetics was observed with respect to CO (Figure 6). 

A quite different equation for the quantification of substrate inhibition kinetics has been proposed by Tseng and Waymann (1975) (Waymann and Tseng, 1976). Substrate concentrations higher than a characteristic threshold substrate concentration inhibited growth linearly in accordance with... 

The performance of CSTR is drastically changed by substrate inhibition kinetics. All systems previously presented have the property of equifmality, with only one unique steady state, and the attraction domain contains all states. But in nonlinear open systems, additional steady states and additional attraction domains are possible. A CSTR with S inhibition is an example where there are two stable steady states ( x, and s) and where the phase plane is dissected in two nonoverlapping attraction domains. 

It is clear that for Michaelis-Menten kinetics, we have only one steady state for the whole range of D, whereas for the substrate-inhibited kinetics, we can have more than one steady state over a certain range of D values (this can be easily visualized by Fig. 3.16). 

Substrate inhibited kinetics already at 200 mM even at lower concentration with Haldane equation prediction. 

---