Effects of various salts on structural polymorphism of reconstituted type I collagen fibrils

Yuping Li, Elliot P. Douglas

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Even though the behavior of collagen monomers self-assembling into fibrils is commonly understood in terms of hydrophobic and electrostatic interactions, the mechanisms that drive their ordered, longitudinal alignment to form a characteristic periodicity are still unclear. By introducing various salts into the collagen fibrillogenesis system, the intermolecular interactions of fibril formation were studied. We found that the pH and ion species play a critical role in forming native fibrils. Turbidity and electron microscopy revealed that collagen self-assembled into fibrils with a native banding pattern in the presence of multivalent ions. The isoelectric point of collagen in 12mM of NaCl is pH 8.9; it shifted to pH 9.4 and pH 7.0 after adding 10mM CaCl2 and Na2SO4, respectively. Native fibrils were reconstituted at pH 7.4 in salts with divalent anions and at pH 9.0 in salts with divalent cations. Circular dichroism spectroscopy showed a loss of helicity in the conditions where fibrillogenesis was unable to be achieved. The multivalent ions not only change the surface charge of collagen, but also facilitate the formation of fibrils with the native D-periodic banding pattern. It is likely that the binding multivalent ions induce the like-charge attraction and facilitate monomers' longitudinal registration to form fibrils with the native banding.

Original languageEnglish (US)
Pages (from-to)42-50
Number of pages9
JournalColloids and Surfaces B: Biointerfaces
Volume112
DOIs
StatePublished - Dec 1 2013

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation Grant BES-0404000 . The authors thank the Major Analytical Instrumentation Center (MAIC), Department of Materials Science and Engineering, University of Florida for the use of TEM, SEM and AFM; the Particle Engineering Research Center, University of Florida for the use of Zeta-Plus.

Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.

Keywords

  • Banding pattern
  • D-periodicity
  • Electrostatic interactions
  • Fibril
  • Salt bridge
  • Surface charge

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