Protecting role of cosolvents in protein denaturation by SDS: a ...

Recently, we reported a unique approach to preserve the activity ofsome proteins in the presence of the denaturing agent, SodiumDodecyl Sulfate (SDS). This was made possible by addition of theamphipathic solvent 2,4-Methyl-2-PentaneDiol (MPD), used asprotecting but also as refolding agent for these proteins.

Although the persistence of the protein activity in the SDS/MPDmixture was clearly established, preservation of their structurewas only speculative until now.

Results: In this paper, a detailed X-ray study addresses thepending question.

Crystals of hen egg-white lysozyme were grown for the first time inthe presence of MPD and denaturing concentrations of SDS. Dependingon crystallization conditions, tetragonal crystals in complex witheither SDS or MPD were collected.

The conformation of both structures was very similar to the nativelysozyme and the obtained complexes of SDS-lysozyme andMPD-lysozyme give some insights in the interplay of protein-SDS andprotein-MPD interactions.

Conclusions: This study clearly established the preservation of theenzyme structure in a SDS/MPD mixture. It is hypothesized that highconcentrations of MPD would change the properties of SDS and loweror avoid interactions between the denaturant and the protein.

These structural data therefore support the hypothesis that MPDavoids disruption of the enzyme structure by SDS and can protectproteins from SDS denaturation.
Author: Catherine Michaux, Jenny Pouyez, Johan Wouters and GilbertG Prive
Credits/Source: BMC Structural Biology 2008, 8:29

Published on: 2008-06-03