Desenvolvimento de enzimas imobilizadas em suporte inorgânico e suas aplicações em síntese e resolução quiral

Abstract

The classical thio-Michael reaction, involves the reaction of sulfur atom (nucleophile) with various electrophiles, which can be activated using Lewis acids. However, the use of these metals is harmful to the environment and sometimes they are toxic. An efficient alternative is the use of enzymes as biocatalysts, but one of the most important disadvantages in it process is theenzyme’s solubility in aqueous medium. To solve this problem, an alternative is the enzyme’s immobilization employing methods involving covalent linking using glutaraldehyde. In order to develop less expensive and more efficient supports for enzymes, we synthesized a inorganic suporte using MgCl2 and we immobilized lipase from porcine pancreasand chymosin on it. These immobilized enzymes wereinserted, firstly, in the enzymatic resolution of 3-phenyl-3-phenyltiopropanol using THF, hexane, 1,2- dichloroethane and DMSO as solvent. The results indicated that the chymosin immobilized on MgCl2 support showed to be promising for producing the respectively alcohol (61%) in THF. We also carried out the same reaction varying the catalyst amount (0.1 g, 0.15 g and 0.2 g of immobilized chymosin) using the same solvent. We observed that increasing on thecatalyst amount did not resulted in increase of yields on the other hand, this increasing on catalyst amount produced aslight decreasing on yields. In order to compare the literature data for the 3-phenyl-3-feniltiopropanolsynthesis we inserted the lipase from porcine pancreasimmobilized on MgCl2 support (Mg-LPP) as a biocatalyst in this reaction betweencinnamaldehyde and thiophenol (thio-Michael reaction). The data showed to us a decline in enzyme activity comparing to literature data for the free lipase from porcine pancreas(PPL). Although we had observed a decreasing on enzyme efficiency, we verified that reuse of enzyme was possible for three cycle at least without any loss of yield or biocatalyst mass. Finally, we also inserted LPP and Mg-LPP as biocatalyst in non-natural aminoacidssynthesis and we observed that the supported enzymeproduced an increasing in diastereomeric excess for the interest compound.