Using molecular dynamics simulations to study titration behavior of fatty acids

Sammanfattning: Medium chain fatty acids (MCFAs) are essential molecules for a wide range of pharmaceutical, biotechnological, and industrial applications. These are naturally occurring saturated or unsaturated fatty acids containing 6-12 carbons with complex and pH sensitive aggregation. Medium chain fatty acids such as capric acid (C10) or lauric acid (C12) have additionally been shown to exhibit antibacterial activity. A number of studies have observed the aggregation behavior of long chain fatty acid using the titration curves by molecular dynamic (MD) simulations.  In this study, we performed constant-pH coarse-grained MD simulations to determine pKa values and titration behavior using a two-states model for C10 and C12. In the simulations, pH was varied between 2 to 8 and pKa values were determined using the Hill equation. The pKa for C10 (capric acid) was found to be 4.8 and for C12 (lauric acid) 5.4, in good agreement with the literature values (4.9 and 5.3, respectively).