Article

Molecular modelling of lipase-catalyzed polyester synthesis

Journal of Biotechnology 01/1997; 52(3):267-275. DOI:10.1016/S0168-1656(96)01651-3

ABSTRACT Molecular dynamics simulations and electrostatic potential calculations were used to study the structure of a Rhizomucor miehei lipase (RmL)–substrate complex in a lipase catalyzed polyester synthesis. Two lipase–substrate complexes were constructed with sebacic acid and 1,4-butyl sebacate as substrates, energy minimized, and simulated for 100 ps. During the simulation, catalytically important hydrogen bonds were formed more easily, when the acid was placed in the hydrophobic end and the ester in the hydrophilic end of the active centre. However, also the polarity of the active centre amino acids probably affects the placement of the substrates. The electrostatic potential calculations showed significant differences in the electrostatic potential of the surface of RmL. This may help the lipase to orientate itself appropriately for the interfacial reaction.

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    ABSTRACT: The interest in the applications of biocatalysis in organic syntheses has rapidly increased. In this context, lipases have recently become one of the most studied groups of enzymes. We have demonstrated that lipases can be used as biocatalyst in the production of useful biodegradable compounds. A number of examples are given. 1-Butyl oleate was produced by direct esterification of butanol and oleic acid to decrease the viscosity of biodiesel in winter use. Enzymic alcoholysis of vegetable oils without additional organic solvent has been little investigated. We have shown that a mixture of 2-ethyl-1-hexyl esters can be obtained in a good yield by enzymic transesterification from rapeseed oil fatty acids for use as a solvent. Trimethylolpropane esters were also similarly synthesized as lubricants. Finally, the discovery that lipases can also catalyze ester syntheses and transesterification reactions in organic solvent systems has opened up the possibility of enzyme catalyzed production of biodegradable polyesters. In direct polyesterification of 1,4-butanediol and sebacic acid, polyesters with a mass average molar mass of the order of 56,000 g mol-1 or higher, and a maximum molar mass of about 130,000 g mol-1 were also obtained by using lipase as biocatalyst. Finally, we have demonstrated that also aromatic polyesters can be synthesized by lipase biocatalysis, a higher than 50,000 g mol-1 mass average molar mass of poly(1,6-hexanediyl isophthalate) as an example.
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