Structural behavior of Candida antarctica lipase B in water and supercritical carbon dioxide: A molecular dynamic simulation study

In this study, molecular dynamic (MD) simulation is used to investigate the effect of supercritical carbon dioxide on the structural properties of a new variant of Candida antarctica lipase B, namely, cp283Δ7. For better understanding and comparison, structure of the enzyme was simulated in both water and supercritical carbon dioxide. The analysis of root mean square deviation showed that in supercritical CO2, the structural variations of the enzyme are more than those of in the aqueous solution and therefore dissolving enzyme in scCO2 impose undesirable instability on its structure. Moreover, obtained radius of gyration showed that in supercritical CO2, the compactness of the enzyme structure is reduced which leads to decreased stability. The secondary structure analysis revealed that in supercritical CO2, on the one hand, the amounts of α-helix and β-sheet contents of enzyme are reduced and, on the other hand, the amount of random coil is increased. More native-like enzyme structure was also confirmed in water than supercritical CO2 by tertiary structure analysis in term of contact map.