دانلود رایگان مقاله سورفاکتانت زیست سازگار، متیل استر سولفونات به عنوان لیگاند رسوب

Abstract

A biocompatible surfactant, methyl ester sulphonate (MES), was evaluated in protein surfactant precipitation. The amount of lysozyme precipitated by MES was found to be a strong function of both the molar ratio of surfactant to protein (Rp), and pH. Precipitation increased proportionally with an increase in Rp up to an optimum of 16, where full precipitation was achieved, while with pH variations electrostatic interactions were found to be the main driver of precipitation. The precipitate was recoverable by solvent extraction (54–56% activity recovery by acetone, ethanol, 50% acetone/ethanol, and methanol), and counter-ionic surfactant, TOMAC (83.3% activity recovery at Rr = 1.5). Importantly, the structural integrity ofthe lysozyme recovered, either through solvent extraction or counter-ionic surfactant, was maintained, and this was confirmed by CD spectra and deconvolution. Precipitation with MES was compared to a conventional surfactant, AOT; in contrast with AOT, MES did not resolubilise the precipitate or cause structural transformations at higher Rps. MES exhibited better selectivity than AOT since it had minimal hydrophobic interactions in the absence of electrostatic interactions between the surfactant’s anionic group, and the protein’s positively charged groups (pH > pI). Hence, along with its economic benefits, and environmental features, this work has highlighted the potential of using MES in surfactant precipitation.

5. Conclusions

Overall, it can be concluded that the precipitation level of lysozyme by MES was a strong function of Rp and pH. The optimum Rp was chosento be 16 (100%precipitation) at a pH < pI.It was found that electrostatic interactions were the main driving force behind MES precipitation. The lysozyme precipitate was also successfully recovered using solvent – acetone, ethanol, 50% acetone/ethanol, or methanol (54–56% activity recoveries), or counter-ionic surfactant – TOMAC at Rr = 1.5 (83.3% protein recovery). Most significantly,the structural integrity of all the lysozymes recovered was preserved. In contrast to AOT, MES caused no major structural transformations at higher surfactant concentrations, had minimal hydrophobic interactions with the protein molecules, and exhibits better selectivity than AOT. Hence, along with its economic benefits and environmental features, this work has highlighted the considerable potential of using MES as the precipitant in surfactant precipitation separation, and it can be scaled up easily at very low cost.