Jones, C. W. (Christopher W.), Wang, J. C., Briehl, R. W. and Taylor, Matthew S.. (2005) Measuring forces between protein fibers by microscopy. Biophysical Journal, Vol.88 (No.4). pp. 2433-2441. ISSN 0006-3495

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Abstract

We propose a general scheme for measuring the attraction between mechanically frustrated semiflexible fibers by measuring their thermal fluctuations and shape. We apply this analysis to a system of sickle hemoglobin (HbS) fibers that laterally attract one another. These fibers appear to “zip” together before reaching mechanical equilibrium due to the existence of cross-links into a dilute fiber network. We are also able to estimate the rigidities of the fibers. These rigidities are found to be consistent with sickle hemoglobin “single” fibers 20 nm in diameter, despite recent experiments indicating that fiber bundling sometimes occurs. Our estimate of the magnitude of the interfiber attraction for HbS fibers is in the range 8 ± 7 kBT/μm, or 4 ± 3 kBT/μm if the fibers are assumed, a priori to be single fibers (such an assumption is fully consistent with the data). This value is sufficient to bind the fibers, overcoming entropic effects, although extremely chemically weak. Our results are compared to models for the interfiber attraction that include depletion and van der Waals forces. This technique should also facilitate a similar analysis of other filamentous protein assembles in the future, including β-amyloid, actin, and tubulin.

Item Type:	Journal Article
Subjects:	Q Science > QR Microbiology
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Hemoglobin polymorphisms, Protein binding -- Research, Proteins -- Affinity labeling, Van der Waals forces, Biochemisty
Journal or Publication Title:	Biophysical Journal
Publisher:	Biophysical Society
ISSN:	0006-3495
Date:	April 2005
Volume:	Vol.88
Number:	No.4
Page Range:	pp. 2433-2441
Identification Number:	10.1529/biophysj.104.050856
Status:	Peer Reviewed
Access rights to Published version:	Open Access
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URI:	http://wrap.warwick.ac.uk/id/eprint/909

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