de Morais Junior_2018_Mol.Catal_458_89

Enzymes' stabilization degree and protein structure modification have been associated with different immobilization techniques. Geotrichum candidum lipase (GCL) was immobilized using different supports and immobilization protocols: covalent bonding on Cyanogen bromide activated sepharose (CNBr) and amino-glyoxyl (AMG), and ionic bonding on anionic support diethylaminoethyl (DEAE) and cationic support carboxymethyl agarose. The lipase stability in medium with different pH values and thermal stability of different derivatives of GCL were evaluated for enantioselective hydrolysis of (R,S)-mandelic acid ethyl ester under different pH conditions at the same temperature. The properties of GCL can be modulated by direct immobilization, i.e., immobilization using different supports and the reaction pH conditions changes the catalytic properties leading to different selectivity, consequently improving the biocatalyst properties. Stereochemical preference to the R isomer was observed on carboxymethyl and AMG derivatives at pH 5.0 and 7.0, respectively, with enantiomeric excess higher than 99% and specificity above 200. On the other hand, the reaction has shown stereochemical preference to the S isomer when using CNBr and AMG derivatives at pH 5.0 and 9.0, respectively, achieving an enantiomeric excess higher than 99% and specificity above 200.