Conformational changes of lipases in aqueous media: A comparative computational study and experimental implications

Conformational changes occurring to the open form of five different lipases were studied by means of molecular dynamic simulations in explicit water. The conformational changes indicate remarkable differences among the lipases considered, not only in terms of accessibility of the active site but also of modification of the geometry of the catalytic machinery. Lipase B from Candida antarctica undergoes minor conformational change at either level, so that it appears to be the most suitable lipase for being applied and formulated in aqueous environments or other hydrophilic media. On the other side, lipase from Pseudomonas cepacia undergoes the most relevant conformational variations both at the level of the catalytic triad and the residues involved in the oxyanion stabilization, suggesting that its “interfacial activation” is not simply related to a variation of the accessibility of the active site. Indeed, preliminary experimental data here reported indicate that covalent immobilization of lipase from Pseudomonas cepacia performed in the presence of hydrophobic solvent allows one to achieve a more than 10-fold increase in immobilization yield as compared to similar protocols performed in simple aqueous buffer. On the contrary, the benefit coming from immobilizing lipase B from Candida antarctica in hydrophobic solvent appears more limited (two-fold higher immobilization yield).