Altan, Irem and Khan, Amir R. and James, Susan and Quinn, Michelle K. and McManus, Jennifer and Charbonneau, Patrick (2019) Using Schematic Models to Understand the Microscopic Basis for Inverted Solubility in yD-Crystallin. Journal of Physical Chemistry B, 123. pp. 10061-10072. ISSN 1520-6106

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Abstract

Inverted solubilitymelting a crystal by coolingis observed in a handful of proteins, such as carbomonoxy hemoglobin C and γD-crystallin. In human γD-crystallin, the phenomenon is associated with the mutation of the 23rd residue, a proline, to a threonine, serine, or valine. One proposed microscopic mechanism entails an increase in surface hydrophobicity upon mutagenesis. Recent crystal structures of a double mutant that includes the P23T mutation allow for a more careful investigation of this proposal. Here, we first measure the surface hydrophobicity of various mutant structures of γDcrystallin and discern no notable increase in hydrophobicity upon mutating the 23rd residue. We then investigate the solubility inversion regime with a schematic patchy particle model that includes one of three variants of temperature-dependent patch energies: two of the hydrophobic effect, and one of a more generic nature. We conclude that, while solubility inversion due to the hydrophobic effect may be possible, microscopic evidence to support it in γD-crystallin is weak. More generally, we find that solubility inversion requires a fine balance between patch strengths and their temperature-dependent component, which may explain why inverted solubility is not commonly observed in proteins. We also find that the temperature-dependent interaction has only a negligible impact on liquid−liquid phase boundaries of γD-crystallin, in line with previous experimental observations.

Item Type:	Article
Keywords:	Schematic Models; Microscopic Basis; Inverted Solubility; yD-Crystallin;
Academic Unit:	Faculty of Science and Engineering > Chemistry
Item ID:	13458
Identification Number:	https://doi.org/10.1021/acs.jpcb.9b07774
Depositing User:	Jennifer McManus
Date Deposited:	28 Oct 2020 10:54
Journal or Publication Title:	Journal of Physical Chemistry B
Publisher:	American Chemical Society
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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