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Final Thesis - Kathryn Wilcox.pdf (13.76 MB)

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Elasticity of Biomacromolecular Helices and the Effect of Elasticity on Biological Assembly

Wilcox, Kathryn Grace
http://orcid.org/0000-0002-7436-7716
http://rave.ohiolink.edu/etdc/view?acc_num=case1712324244806058

Abstract Details

2024, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science and Engineering.
Helices are abundant and crucial examples of rigidity throughout biology from protein lever arms in molecular motors to collagen type II that assembles into fibrils in the extracellular matrix (ECM). The origin of the collagen fibril radial length scales is not fully understood but is hypothesized to be related to the flexibility of the protofibril and environmental effects. In this work, we systemically investigate both the elasticity of biomacromolecules and their surrounding elastic environments using simple polyacrylamide gels. We determine the persistence length (lp), a measure of elasticity, of model polypeptide single helices and collagen type II triple helices by using static and dynamic light scattering. Using circular dichroism, we observe that the model polypeptide transitions from a random coil to a helix with increasing pH, and lp increases from ~1 - 2 nm to ~20 nm. In addition, we crosslink the model polypeptide to utilize its increase in lp and produce hydrogels with stain stiffening behavior at low crosslink densities. In various pH and ionic strength environments, triple helical lp varies from 60 - 90 nm but has an intrinsic lp of 90 nm when backbone interactions are neutralized. We correlate the triple helical lp to the fibril diameter as determined by transmission electron microscopy (TEM) in various ionic strength solutions and determine that the values are of similar magnitude unless in high ionic strength solutions. We then investigate the environmental elasticity effects on self-assemblies of complex coacervates using light microscopy and collagen type II fibrils using cryogenic TEM. The volume of the complex coacervate droplets is inversely proportional to the modulus of the gel that the complex coacervates are formed in and have a non-monotonic salt resistance as a function of gel moduli. Collagen fibrils in 100 mM PBS solution are ~50 nm in diameter, and the fibril diameter drops to ~30 nm in gels across 63-8700 Pa moduli. Collagen’s lp, solution [I], and surrounding network play significant roles in fibril formation. These results could lead to further understanding of biomacromolecular assemblies.
Svetlana Morozova (Committee Chair)
Lydia Kisley (Committee Member)
Valentin Rodionov (Committee Member)
Michael Hore (Committee Member)
377 p.
Biophysics; Materials Science; Physics
collagen type II; persistence length; fibril; complex coacervate; hydrogel; polymer gel, poly-L-lysine; elasticity; polyelectrolyte; helix; triple helix; single helix; salt; TEM; SEM; cryo-EM; light scattering; circular dichroism; SLS; DLS

Recommended Citations

Citations

  • Wilcox, K. G. (2024). Elasticity of Biomacromolecular Helices and the Effect of Elasticity on Biological Assembly [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1712324244806058

    APA Style (7th edition)

  • Wilcox, Kathryn. Elasticity of Biomacromolecular Helices and the Effect of Elasticity on Biological Assembly. 2024. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1712324244806058.

    MLA Style (8th edition)

  • Wilcox, Kathryn. "Elasticity of Biomacromolecular Helices and the Effect of Elasticity on Biological Assembly." Doctoral dissertation, Case Western Reserve University, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=case1712324244806058

    Chicago Manual of Style (17th edition)

case1712324244806058
54
© 2024, some rights reserved.Creative Commons License Elasticity of Biomacromolecular Helices and the Effect of Elasticity on Biological Assembly by Kathryn Grace Wilcox is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.
Release 3.2.12