Product inhibition kinetics

Regions of stable and unstable operation determined by numerical simulation of mass and heat balances equations first- and second-order, autocatalytic, and product-inhibited kinetics graphically presented boundaries in co-ordinates in practice. safe operation if l/5e>2. Equality of heat generation and heat removal rates Semenov approach modified for first-order kinetics. 

Product inhibition kinetics performed at saturating levels of one substrate with norlaudanosoline as the inhibitor showed that NCS follows an iso-ordered biuni mechanism with 4-HPAA binding before dopamine (Fig.7.8). These data also imply that 4-HPAA combines with a form of the enzyme different from the alkaloid product since the inhibitor and first substrate do not bind competitively. After the product is released, NCS appears to undergo a conformational change reverting back to a form to which 4-HPAA can bind before another reaction sequence can begin.131... 

Shaughnessy TS Kargi F (1990a) Growth and product inhibition kinetics of T-cell hybridomas producing lymphokines in batch and continuous culture. Enzyme and Microbial Technology 12 669-675. 

Particle mass transfer, product inhibition kinetics, integral packed bed [25]... 

Fig. 4.17 Global effectiveness factor (mean integral value) of an immobilized enzyme with competitive product inhibition kinetics in a spherical particle as a function of bulk substrate concentration and Thiele modulus (K/K = 1 substrate conversion = 0.9)...

When basic design of continuous reactors was presented in section 5.2, CPBR performance was shown to be superior to CSTR for simple Michaelis-Menten kinetics, product inhibition kinetics and sequential mechanisms of two-substrate reactions. However, when considering enzyme inactivation, differences between the two reactor configurations are reduced as time elapses and the enzyme inactivates, as shown in Fig. 5.17 for simple Michaelis-Menten kinetics. The ratio of areas... 

Figure 6.9. Product inhibition kinetics in a CSTR with Xq = 0, demonstrated in a plot of concentration versus time (mean residence time F) cf. Fig. 6.1b, (Levenspiel, 1980).

Figure 6.10. Method for evaluating the rate constants for product inhibition kinetics from CSTR experiments with Xq = 0, according to Equ. 6.33 (Levenspiel, 1980).

Figure 6.25. Demonstration of the advantage of CPFR over CSTR by calculating the volume ratio in dependence of conversion reached (C) as a function of biokinetics using the simple Monod equation and varying the ratio Sq/K and also product inhibition kinetics with variation of Sq/Kj. A. Moser, 1985c, reprinted with permission from Conservation and Recycling, vol. 8, No. 1/2, Pergamon Press, Oxford.)...

Lin CSK, Du CY, Koutinas A, Wang R, Webb C (2008) Substrate and product inhibition kinetics in succinic acid production hy Actinobacillus succinogenes. Biochem Eng J 41 128-135 Lin H, Bennett GN, San KY (2005) Fed-batch culture of a metabolically engineered Escherichia coli strain designed for high-level succinate production and yield under aerobic conditions. Biotechnol Bioeng 90 775-779... 

Lin, S.K.C., Du, G., Koutinas, A., Wang, R., Webb, G., 2008. Substrate and product inhibition kinetics in succinic acid production by Actinobacillus succinogenes. Biochemical Engineering Journal 41 (2), 128-135. 

Usually initial rates are measured in enzyme kinetics so as to avoid problems arising from kinetic complications such as product inhibition. 

Several of the problems associated with whole cell bioprocesses are related to the highly effective metabolic control of microbial cells. Because cells are so well regulated, substrate or product inhibition often limits the concentration of desired product that can be achieved. This problem is often difficult to solve because of a poor understanding of the kinetic characteristics of the metabolic pathway leading to the desired product. 

Substrate and product inhibitions analyses involved considerations of competitive, uncompetitive, non-competitive and mixed inhibition models. The kinetic studies of the enantiomeric hydrolysis reaction in the membrane reactor included inhibition effects by substrate (ibuprofen ester) and product (2-ethoxyethanol) while varying substrate concentration (5-50 mmol-I ). The initial reaction rate obtained from experimental data was used in the primary (Hanes-Woolf plot) and secondary plots (1/Vmax versus inhibitor concentration), which gave estimates of substrate inhibition (K[s) and product inhibition constants (A jp). The inhibitor constant (K[s or K[v) is a measure of enzyme-inhibitor affinity. It is the dissociation constant of the enzyme-inhibitor complex. 

The 2-ethoxyethanol was a by-product, as shown in Figure 5.13. The formation rate of 2-ethoxyethanol was the same as the conversion rate of the (S)- or (R)-ibuprofen ester one mole of 2-ethoxyethanol was formed when one mole of ester was catalysed. A known concentration of 2-ethoxyethanol was added in the organic phase before the start of the reaction for product inhibition. The plots of the kinetics for the free lipase system are presented in Figure 5.17 and immobilised enzyme (EMR) in Figure 5.18, respectively. The Kw value was 337.94 mmoFl 1 for the free lipase batch system and 354.20 mmoll 1 for immobilised... 

Rg. 5.20. Kinetics mechanism with uncompetitive substrate inhibition and non-competitive product inhibition. 

Product inhibition studies are used to complement kinetic analyses and to distinguish between ordered and random Bi-Bi reactions. For example, in a random-order Bi-Bi reaction, each product will be a competitive inhibitor regardless of which substrate is designated the variable substrate. However, for a sequential mechanism (Figure 8-11, bottom), only product Q will give the pattern indicative of competitive inhibition when A is the variable substrate, while only product P will produce this pattern with B as the variable substrate. The... 

The reaction rate for this enzyme kinetics example is expressed by the Michaelis-Menten equation and with product inhibition. 

The kinetic equation used here is an enzymatic Michaelis-Menten form with product inhibition... 

This same [e] experimental protocol leads to a graphical overlay plot that yields valuable kinetic information if the two experiments described in Table 50.1 are plotted together as reaction rate vs. [2], the two curves will fall on top of one another ( overlay ) over the range of [2] common to both only if the rate is not significantly influenced by changes in the overall catalyst concentration within the cycle, including catalyst activation, deactivation or product inhibition. Overlay in same excess plots, therefore, may be used to confirm catalyst robustness or identify problems such as catalyst deactivation or product inhibition. 

More information on the square root law and on kinetic and thermodynamic aspects of the minimal replicator theory can be found in the literature (von Kiedrowski, 1999 and 1993). The square root law has its origin in the product inhibition involved in the mechanism of self-replication. The more C units are formed, the greater is the tendency of the molecules of C to dimerize to give C2 this species, however, cannot function as a catalyst. 

PFR. The reaction volume increases indefinitely as Dye is increased, for a given value of the final dye concentration to an extent that depends on the possible product-inhibited character of the reaction kinetics. 

Conversion rate data obtained under a wide range of operating conditions may be worked out to provide a kinetic expression, most typically expressed according to well established models for bioprocess kinetics first and second order, Monod, Haldane, product-inhibited, etc. 

Results have generally been disappointing. It can be difficult to remove the TSA from the polymer, but a more fundamental problem concerns the efficiency of the catalysis observed. The most efficient systems catalyze the hydrolysis of carboxylate and reactive phosphate esters with Michaelis-Menten kinetics and accelerations (koAJKM)/kunoJ approaching 103,1661 but the prospects for useful catalysis of more complex reactions look unpromising. Apart from the usual difficulties the active sites produced are relatively inflexible, and the balance between substrate binding and product inhibition is particularly acute. 

Kinetic analysis revealed that this reaction is pseudo-first order in dienophile at low conversions (200). At higher conversions, the rate deviates from a linear relationship, suggestive of product inhibition. Indeed, addition of product to the reaction at the start resulted in a decrease in rate by 18%. A number of competitive inhibitors were identified in this study. Particularly interesting was the observation that the matched chiral dienophile product was less effective as an inhibitor than the mismatched product. The authors suggest that the sterically matched complex (where the ligand bulk and imide chirality is on the same side of the complex) is thermodynamically less stable than the mismatched complex. 

Mechanisms of Enzyme Action, Use of Product Inhibition and Other Kinetic Methods in the Study of (Walter). Mechanisms of Organic Electrode Reactions (Elving Pullman). ... 

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