Mycobacterium smegmatis acyltransferase catalyzes the synthesis of esters and polyesters

Abstract

In the present work, Mycobacterium smegmatis acyltransferase (MsAcT) was successfully immobilized onto polypropylene beads and the selectivity was investigated both in esterification and polycondensation reactions. All the syntheses were carried out under solventless conditions at room temperature to better comply with today's green chemistry principles. Therefore, ester synthesis was performed according to the planned full-factorial design of experiments (DoE) investigation to study MsAcT selectivity towards ester functional groups (vinyl, ethyl, and methyl), alcohol carbon chain length (C₄, C₈, C₁₂) and ester carbon chain length (C₂, C₄, C₆). The results clearly showed MsAcT selectivity towards vinyl esters (vinyl- > ethyl- > methyl-) and short-chain compounds (C₂ esters and C₄ alcohol). Moreover, to confirm the obtained DoE model in ester synthesis, the immobilized MsAcT formulation was used to perform polycondensation reactions using bio-based diesters and diols. Higher conversion rates were obtained using ethylene glycol when compared to 1,4-butanediol in polyester synthesis with divinyl adipate as the diesters and at different time-lengths of applied vacuum (20 mbar). This resulted in agreement with the selectivity of MsAcT in esterification reactions. Furthermore, divinyl succinate (DVS) was used in polycondensations and all the resulting oligomers were analyzed via GPC and LC-MS.