Minute Additions of DMSO Affect Protein Dynamics Measurements by NMR Relaxation Experiments through Significant Changes in Solvent Viscosity

Wallerstein, JohanLund University,Lunds universitet,Biofysikalisk kemi,Centrum för Molekylär Proteinvetenskap,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biophysical Chemistry,Center for Molecular Protein Science,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH (author)

Studies of protein−ligand binding often rely on dissolving the ligand in dimethyl sulfoxide (DMSO) to achieve sufficient solubility, and then titrating the ligand solution into the protein solution. As a result, the final protein−ligand solution contains small amounts of DMSO in the buffer. Here we report how the addition of DMSO impacts studies of protein conformational dynamics. We used 15N NMR relaxation to compare the rotational diffusion correlation time (τC) of proteins in aqueous buffer with and without DMSO. We found that τC scales with the viscosity of the water−DMSO mixture, which depends sensitively on the amount of DMSO and varies by a factor of 2 across the relevant concentration range. NMR relaxation studies of side chains dynamics are commonly interpreted using τC as a fixed parameter, obtained from backbone 15N relaxation data acquired on a separate sample. Model-free calculations show that errors in τC, arising from mismatched DMSO concentration between samples, lead to significant errors in order parameters. Our results highlight the importance of determining τC for each sample or carefully matching the DMSO concentrations between samples.

Akke, MikaelLund University,Lunds universitet,Biofysikalisk kemi,Centrum för Molekylär Proteinvetenskap,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biophysical Chemistry,Center for Molecular Protein Science,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)fkm2-mak (author)
Biofysikalisk kemiCentrum för Molekylär Proteinvetenskap (creator_code:org_t)

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Biological Scien ...; and Biochemistry and ...

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.