Kinetic viscosity enzymes

Figure 11 Release kinetics of enzymes released from ATRIGEL formulations ri.horseradish peroxidase O, trypsin O, lysozyme. Formulations consisted of PLA (inherent viscosity, 0.05), using polyvinylpyrrolidone and calcium phosphate as additives. Formulation solvent was NMP, and the protein load was 5%. Cumulative release profiles were generated in PBS, pH 7.4.

There is currently little understanding of the influence of interfacial composition and (nano)structure on the kinetics of enzymatic hydrolysis of biopolymers and lipids. However, a few preliminary studies are beginning to emerge (McClements et al., 2008 Dickinson, 2008). Thus, for example, Jourdain et al. (2009) have shown recently that, in a mixed5 sodium caseinate + dextran sulfate system, the measured interfacial viscosity increased from qs = 220 mN s m 1 without enzyme to qs = 950 mN s m 1 with trypsin present. At the same time, the interfacial elasticity was initially slightly reduced from (7S = 1.6 mN m 1 to (h = 0.7 mN m, although it later returned to close to its original value. Conversely, in the... 

Recent studies in the pharmaceutical field using MBR technology are related to optical resolution of racemic mixtures or esters synthesis. The kinetic resolution of (R,S)-naproxen methyl esters to produce (S)-naproxen in emulsion enzyme membrane reactors (E-EMRs) where emulsion is produced by crossflow membrane emulsification [38, 39], and of racemic ibuprofen ester [40] were developed. The esters synthesis, like for example butyl laurate, by a covalent attachment of Candida antarctica lipase B (CALB) onto a ceramic support previously coated by polymers was recently described [41]. An enzymatic membrane reactor based on the immobilization of lipase on a ceramic support was used to perform interesterification between castor oil triglycerides and methyl oleate, reducing the viscosity of the substrate by injecting supercritical CO2 [42],... 

The conditions that most favored mass transfer of anthracene (250 and 300 rpm and presence of Triton X-100) were evaluated in terms of enzyme inactivation as well as all viscosities of silicone oil. Inactivation coefficients, kd, were calculated according to first-order kinetics (Fig. 10.14). The increase of the agitation rate to 300 rpm did not have a remarkable effect on the inactivation in presence of Triton, whereas in aqueous medium inactivation coefficients slightly increased. The viscosity of solvent does not seem to affect inactivation, except for 10 cSt, which led to the highest values. 

This is a technological constraint, where the summation covers all enzyme fluxes (z in number, 30 in our case), nref is the i reference enzymatic reaction rate given in Table 13.1. Total enzymatic activity is constrained not to exceed 1.0 to avoid diffusion problem (due to increased cytoplasm viscosity), protein precipitation, secondary kinetic effects (due to steric hindrance) and excessive intracellular stress leading to unpredictable regulatory effects. When either one of these two constraints is breached, the objective function value is penalized by setting it to an arbitrarily low level under such conditions, the DAHPS, PEPCxylase and SerSynth fluxes are set to 10 °. 

The response (a decrease of viscosity) is a direct consequence of the action of the enzyme on its substrate, since the splitting of the glycosidic bonds gives a decrease in the viscosimetric average molecular weight and hydrodynamic volume of the hyaluronan chains and hence a decrease in the intrinsic and relative viscosities. With this method the rate at different concentrations cannot be compared because the initial viscosities are different and rheological measurements do not coincide. To eliminate these problems, a kinetic dilution methodology for the viscosimetric study of the substrate concentration dependence of the action of hyaluronidase was proposed [135,136]. We were able to determine the rate of reaction, expressed as the number of moles of bonds broken per unit of time, from viscosimetric data [136]. 

The first term in the denominator of Eq. (66) represents a non-competitive inhibition (compare to Eq. (31)) of the enzyme by the sum of concentrations of A, B and P. This non-specific inhibition could be correlated with an increased viscosity of the reaction medium in the presence of A, B and P147- mi. As the mutarotation of the carbohydrates is fast compared to the enzymatic reaction there was no need for a discrimination between the a,P-anomers or the open-chain form of the monosaccharides. A complete set of kinetic parameters was determined, summarized in Table 7-4. 

Enzyme Kinetics. The change in the number-average molecular weight of gelatin with time was determined as follows. Measurements of viscosity at known concentrations were extrapolated to infinite dilution to obtain the intrinsic viscosity r from Huggins and Kramer s equations,... 

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