BioEngineering Research GroupAppl. Biochem. Biotechnol., 61, 299-314 (1996)
Castellar, M. R., Taipa, M. A., Cabral, J. M. S.
A kinetic study of Chromobacterium viscosum lipase was undertaken, and compared with Pseudomonas glumae lipase. Optimum operation conditions were pH 9.0 and 50ºC for both enzymes. A substrate specificity study was also developed. Both enzymes showed higher activity on triglycerides with a long chain of fatty acid; the specific activity was always higher for C. viscosum lipase. Stability of both enzymes in aqueous medium at 60ºC and pH 9.0 was evaluated. C. viscosum lipase was three times more stable than P. glumae lipase, with a t1/2 value of 0.75 h. In addition, the activity of C. viscosum lipase with substrate concentration was studied with a triolein emulsion. A dependence of the intrinsic characteristics of the emulsion was observed. Therefore, stability of C. viscosum lipase B with reaction products was assayed in a micellar system. Acid products reduced the specific activity of the enzyme. Glycerol and high buffer concentration were stabilizers of enzyme deactivation. Finally, substrate specificity of C. viscosum lipase B in a micellar system was developed with tributyrin, tricaprylin, and triolein. Only tributyrin showed an apparent Michaelis-Menten kinetic with Vmax(app) = 958 U/mg and Km(app) = 75.5 mM. Tricaprylin and triolein showed diffusion limitations at low substrate concentration and substrate inhibition at high substrate concentration. Diffusion parameters were calculated for both these substrates. Mass transfer coefficients (kL) were 0.314 Å/min and 1.53 Å/min for tricaprylin and triolein, respectively. Effectiveness factors (h) were 0.536 and 0.768 for tricaprylin and triolein, respectively.
Keywords: Chromobacterium viscosum; Pseudomonas glumae; lipase; triglyceride hydrolysis; emulsion system; reversed micelles
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