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Effect of pressure on the extractive biocatalysis of ethanol
Author(s) -
Marques P. A. S. S.,
Palavra A. M. F.,
Cabral J. M. S.
Publication year - 1992
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.280550105
Subject(s) - chemistry , substrate (aquarium) , lipase , ethanol , oleic acid , kinetics , biocatalysis , atmospheric pressure , enzyme , reaction rate , aqueous solution , chromatography , organic chemistry , catalysis , reaction mechanism , biochemistry , oceanography , physics , quantum mechanics , geology
The effect of pressure on the esterification reaction of ethanol with water‐immiscible organic acids, catalysed by a lipase from Mucor miehei (pH 4.5; 30°C), was studied through analysis of the kinetics and equilibrium parameters. An increase of the ethanol distribution between the aqueous and organic phases was observed by the addition of lipase and the increase of the pressure in the system. Furthermore, the enzyme showed high specificity for the acid substrate, esterifying preferentially long chain fatty acids (C 8 ‐C 18 ). In the studies described oleic acid was used as substrate for the esterification reaction. A kinetic study with the free enzyme, showed that pressure affected the extraction system, increasing the maximum reaction rate (> V max ), the affinity (< K m ) and the specificity (> V max / K m = k sp ) of the enzyme to the substrate, probably due to the effect of pressure on the electrostatic interactions in biological systems. The enzyme operational stability, at 30°C, improved significantly with the increase of pressure, having lower values for the deactivation constant ( k ) (8.3 × 10 −3 h −1 ) and higher values for the half‐life times ( t 1/2 ) (77 h) in comparison with those obtained under atmospheric pressure conditions ( k = 2.3 × 10 −2 h −1 ; t 1/2 = 30 h).