Effects of proteins on protein diffusion. J Am Chem Soc 2010 Jul 14;132(27):9392-7
Date
06/22/2010Pubmed ID
20560582Pubmed Central ID
PMC2898919DOI
10.1021/ja102296kScopus ID
2-s2.0-77955686807 (requires institutional sign-in at Scopus site) 250 CitationsAbstract
Despite increased attention, little is known about how the crowded intracellular environment affects basic phenomena like protein diffusion. Here, we use NMR to quantify the rotational and translational diffusion of a 7.4-kDa test protein, chymotrypsin inhibitor 2 (CI2), in solutions of glycerol, synthetic polymers, proteins, and cell lysates. As expected, translational diffusion and rotational diffusion decrease with increasing viscosity. In glycerol, for example, the decrease follows the Stokes-Einstein and Stokes-Einstein-Debye laws. Synthetic polymers cause negative deviation from the Stokes laws and affect translation more than rotation. Surprisingly, however, protein crowders have the opposite effect, causing positive deviation and reducing rotational diffusion more than translational diffusion. Indeed, bulk proteins severely attenuate the rotational diffusion of CI2 in crowded protein solutions. Similarly, CI2 diffusion in cell lysates is comparable to its diffusion in crowded protein solutions, supporting the biological relevance of the results. The rotational attenuation is independent of the size and total charge of the crowding protein, suggesting that the effect is general. The difference between the behavior of synthetic polymers and protein crowders suggests that synthetic polymers may not be suitable mimics of the intracellular environment. NMR relaxation data reveal that the source of the difference between synthetic polymers and proteins is the presence of weak interactions between the proteins and CI2. In summary, weak but nonspecific, noncovalent chemical interactions between proteins appear to fundamentally impact protein diffusion in cells.
Author List
Wang Y, Li C, Pielak GJAuthor
Yaqiang Wang PhD, MS Assistant Professor in the Biophysics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
DiffusionGlycerol
Motion
Peptides
Plant Proteins
Polymers
Proteins
Rotation
Solutions
Viscosity
