This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.105.075333v1 91/3/1008    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Turner, M. S. Articles by Briehl, R. W. Search for Related Content PubMed PubMed Citation Articles by Turner, M. S. Articles by Briehl, R. W.

Fiber Depolymerization

M. S. Turner ^*, G. Agarwal , C. W. Jones ^*, J. C. Wang , S. Kwong , F. A. Ferrone , R. Josephs  and R. W. Briehl 

^* Department of Physics, University of Warwick, Coventry, United Kingdom; Department of Physiology & Biophysics, Albert Einstein College of Medicine, Bronx, New York; Department of Physics, Drexel University, Philadelphia, Pennsylvania; and Department of Molecular Genetics & Cell Biology, University of Chicago, Chicago, Illinois

Correspondence: Address reprint requests to Dr. Matthew S. Turner, Tel.: 44-24-7652-2257; E-mail: m.s.turner{at}warwick.ac.uk.

Depolymerization is, by definition, a crucial process in the reversible assembly of various biopolymers. It may also be an important factor in the pathology of sickle cell disease. If sickle hemoglobin fibers fail to depolymerize fully during passage through the lungs then they will reintroduce aggregates into the systemic circulation and eliminate or shorten the protective delay (nucleation) time for the subsequent growth of fibers. We study how depolymerization depends on the rates of end- and side-depolymerization, k_end and k_side, which are, respectively, the rates at which fiber length is lost at each end and the rate at which new breaks appear per unit fiber length. We present both an analytic mean field theory and supporting simulations showing that the characteristic fiber depolymerization time depends on both rates, but not on the fiber length L, in a large intermediate regime 1 << k_sideL²/k_end << (L/d)², with d the fiber diameter. We present new experimental data which confirms that both mechanisms are important and shows how the rate of side depolymerization depends strongly on the concentration of CO, acting as a proxy for oxygen. Our theory remains rather general and could be applied to the depolymerization of an entire class of linear aggregates, not just sickle hemoglobin fibers.