Anomalous Diffusion of Proteins Due to Molecular Crowding Export

@article{citeulike:3152136, abstract = {We have studied the diffusion of tracer proteins in highly concentrated random-coil polymer and globular protein solutions imitating the crowded conditions encountered in cellular environments. Using fluorescence correlation spectroscopy, we measured the anomalous diffusion exponent{alpha} characterizing the dependence of the mean-square displacement of the tracer proteins on time, [\&lt;]r2(t)[\&gt;] [\~{}] t{alpha}. We observed that the diffusion of proteins in dextran solutions with concentrations up to 400 g/l is subdiffusive ({alpha} < 1) even at low obstacle concentration. The anomalous diffusion exponent{alpha} decreases continuously with increasing obstacle concentration and molecular weight, but does not depend on buffer ionic strength, and neither does it depend strongly on solution temperature. At very high random-coil polymer concentrations, {alpha} reaches a limit value of{alpha} l {approx} 3/4, which we take to be the signature of a coupling between the motions of the tracer proteins and the segments of the dextran chains. A similar, although less pronounced, subdiffusive behavior is observed for the diffusion of streptavidin in concentrated globular protein solutions. These observations indicate that protein diffusion in the cell cytoplasm and nucleus should be anomalous as well, with consequences for measurements of solute diffusion coefficients in cells and for the modeling of cellular processes relying on diffusion. 10.1529/biophysj.104.051078}, author = {Banks, Daniel S. and Fradin, Cecile}, citeulike-article-id = {3152136}, citeulike-linkout-0 = {http://dx.doi.org/10.1529/biophysj.104.051078}, citeulike-linkout-1 = {http://www.biophysj.org/cgi/content/abstract/89/5/2960}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/16113107}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=16113107}, day = {1}, doi = {10.1529/biophysj.104.051078}, journal = {Biophys. J.}, month = {November}, number = {5}, pages = {2960--2971}, posted-at = {2008-11-02 17:59:11}, priority = {2}, title = {Anomalous Diffusion of Proteins Due to Molecular Crowding}, url = {http://dx.doi.org/10.1529/biophysj.104.051078}, volume = {89}, year = {2005} }

TY - JOUR ID - citeulike:3152136 L3 - citeulike-article-id:3152136 N2 - We have studied the diffusion of tracer proteins in highly concentrated random-coil polymer and globular protein solutions imitating the crowded conditions encountered in cellular environments. Using fluorescence correlation spectroscopy, we measured the anomalous diffusion exponent{alpha} characterizing the dependence of the mean-square displacement of the tracer proteins on time, [&lt;]r2(t)[&gt;] [~] t{alpha}. We observed that the diffusion of proteins in dextran solutions with concentrations up to 400 g/l is subdiffusive ({alpha} < 1) even at low obstacle concentration. The anomalous diffusion exponent{alpha} decreases continuously with increasing obstacle concentration and molecular weight, but does not depend on buffer ionic strength, and neither does it depend strongly on solution temperature. At very high random-coil polymer concentrations, {alpha} reaches a limit value of{alpha} l {approx} 3/4, which we take to be the signature of a coupling between the motions of the tracer proteins and the segments of the dextran chains. A similar, although less pronounced, subdiffusive behavior is observed for the diffusion of streptavidin in concentrated globular protein solutions. These observations indicate that protein diffusion in the cell cytoplasm and nucleus should be anomalous as well, with consequences for measurements of solute diffusion coefficients in cells and for the modeling of cellular processes relying on diffusion. 10.1529/biophysj.104.051078 IS - 5 JF - Biophys. J. EP - 2971 TI - Anomalous Diffusion of Proteins Due to Molecular Crowding VL - 89 SP - 2960 AU - Banks, Daniel AU - Fradin, Cecile PY - 2005/11/01/ UR - http://dx.doi.org/10.1529/biophysj.104.051078 ER -