Micromechanics of isolated sickle cell hemoglobin fibers: Bending moduli and persistence lengths

Jiang Cheng Wang, Matthew S. Turner, Gunjan Agarwal, Suzanna Kwong, Robert Josephs, Frank A. Ferrone, Robin W. Briehl

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

Pathogenesis in sickle cell disease depends on polymerization of deoxy-hemoglobin S into rod-like fibers, forming gels that rigidify red cells and obstruct the systemic microvasculature. Fiber structure, polymerization kinetics and equilibria are well characterized and intimately related to pathogenesis. However, data on gel rheology, the immediate cause of obstruction, are limited, and models for structure and rheology are lacking. The basis of gel rheology, micromechanics of individual fibers, has never been examined. Here, we isolate fibers by selective depolymerization of gels produced under photolytic deliganding of CO hemoglobin S. Using differential interference contrast (DIC) microscopy, we measure spontaneous, thermal fluctuations in fiber shape to obtain bending moduli (κ) and persistence lengths (λp). Some fibers being too stiff to decompose shape accurately into Fourier modes, we measure deviations of fiber midpoints from mean positions. Serial deviations, sufficiently separated to be independent, exhibit Gaussian distributions and provide mean-squared fluctuation amplitudes from which κ and λp can be calculated. λp ranges from 0.24 to 13 mm for the most flexible and stiffest fibers, respectively. This large range reflects formation of fiber bundles. If the most flexible are single fibers, then λp = 13 mm represents a bundle of seven single fibers. Preliminary data on the bending variations of frozen, hydrated single fibers of HbS obtained by electron microscopy indicate that the value 0.24 mm is consistent with the persistence length of single fibers. Young's modulus is 0.10 GPa, less than for structural proteins but much larger than for extensible proteins. We consider how these results, used with models for cross-linking, may apply to macroscopic rheology of hemoglobin S gels. This new technique, combining isolation of hemoglobin S fibers and measurement of micromechanical properties based on thermal fluctuations and midpoint deviations, can be used to study fibers of mutants, hemoglobin A/S, and mixtures and hybrids of hemoglobin S.

Original languageEnglish (US)
Pages (from-to)601-612
Number of pages12
JournalJournal of Molecular Biology
Volume315
Issue number4
DOIs
StatePublished - 2002

Fingerprint

Sickle Hemoglobin
Rheology
Gels
Polymerization
Hot Temperature
Interference Microscopy
Hemoglobin A
Elastic Modulus
Normal Distribution
Sickle Cell Anemia
Carbon Monoxide
Microvessels
Electron Microscopy
Proteins

Keywords

  • Fibers
  • Gel
  • Micromechanics
  • Persistence length
  • Sickle hemoglobin

ASJC Scopus subject areas

  • Virology

Cite this

Wang, J. C., Turner, M. S., Agarwal, G., Kwong, S., Josephs, R., Ferrone, F. A., & Briehl, R. W. (2002). Micromechanics of isolated sickle cell hemoglobin fibers: Bending moduli and persistence lengths. Journal of Molecular Biology, 315(4), 601-612. https://doi.org/10.1006/jmbi.2001.5130

Micromechanics of isolated sickle cell hemoglobin fibers : Bending moduli and persistence lengths. / Wang, Jiang Cheng; Turner, Matthew S.; Agarwal, Gunjan; Kwong, Suzanna; Josephs, Robert; Ferrone, Frank A.; Briehl, Robin W.

In: Journal of Molecular Biology, Vol. 315, No. 4, 2002, p. 601-612.

Research output: Contribution to journalArticle

Wang, JC, Turner, MS, Agarwal, G, Kwong, S, Josephs, R, Ferrone, FA & Briehl, RW 2002, 'Micromechanics of isolated sickle cell hemoglobin fibers: Bending moduli and persistence lengths', Journal of Molecular Biology, vol. 315, no. 4, pp. 601-612. https://doi.org/10.1006/jmbi.2001.5130
Wang, Jiang Cheng ; Turner, Matthew S. ; Agarwal, Gunjan ; Kwong, Suzanna ; Josephs, Robert ; Ferrone, Frank A. ; Briehl, Robin W. / Micromechanics of isolated sickle cell hemoglobin fibers : Bending moduli and persistence lengths. In: Journal of Molecular Biology. 2002 ; Vol. 315, No. 4. pp. 601-612.
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