✍ Scribed by Tamer Uçar; H. Ibrahim Ekiz; M. Arif Caglar
No coin nor oath required. For personal study only.
In the study of hydrolysis of tributyrin by the lipase of Candida cylindracea, it is shown that initial rates of hydrolysis are directly proportional to the amount of enzyme adsorbed at the substrate-water interface. As a consequence of understanding the role of the physical state of the substrate in aqueous reaction media, it was hypothesized that the inclusion of synthetic (nonsubstrate) surfaces into the reaction media may enhance the hydrolysis rate of simple liquid lipids which are partly soluble in water, like triacetin. Nonpolar n-hydrocarbons having 5-11 carbon atoms were used to create interfaces in the hydrolysis of triacetin in the soluble range. All of the C5-Cll hydrocarbons showed an activating effect. For quantitative evaluation of the effects of n-hydrocarbons, n-heptane was chosen as the model n-hydrocarbon. Interrelations between the reaction kinetics and adsorption of the enzyme at the n-heptanewater interface were experimentally determined by the use of the same in-line filtration device used for the tributyrin-water system. At 35°C and pH 6 the relative values of the rate constants for the decomposition of enzyme-interface-substrate complexes were calculated as 12 and 1 for the tributyrin and n-heptane-triacetin systems, respectively. The nature of activation at the solvent surfaces were accounted for by a kinetic model which assumes simultaneous adsorption of enzyme and triacetin molecules at the n-heptane-water interface. Making use of the proposed model, the value of a the apparent Michaelis constant for the soluble triacetin-nheptane system at constant n-heptane concentration, 2 vol %, was calculated as 0.044 mol/L.
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Lipase (EC 3.1.1.3) from Candida rugosa was immobilized with DEAE-Sephadex A50, Sephadex G50, Sephadex LH-20, Amberlite IRA94, and Amberlite XAD-7. The enzyme immobilized with DEAE-Sephadex A50 was found to be most effective for continuous hydrolysis of olive oil in isooctane. For the continuous rea