Like-Charge Attraction Between Biomolecules

First figure: Schematic representation of like-charge attraction between negatively charged actin protein rods (green). The red dots are positively charged barium ions that mediate the attraction. Remarkably, these tiny ions cause the comparatively huge actin molecules to twist, a feat that is portrayed by the arrows.
(Image courtesy of Gerard C.L. Wong, University of Illinois at Urbana-Champaign.)

Associated reference: Thomas E. Angelini, Hongjun Liang, Willy Wriggers, and Gerard C. L. Wong, Like-charge attraction between polyelectrolytes induced by counterion charge density waves, Proceedings of the National Academy of Sciences 100, 8634 (2003).

Second figure: Through the mechanism of like-charge attraction, actin rods can arrange themselves into a stack of 2-dimensional "rafts." This structure represents a novel phase of liquid crystalline matter.

Image credit: Gerard C. L. Wong, Alison Lin, Jay X. Tang, Youli Li, Paul A. Janmey, and Cyrus R. Safinya, "Lamellar Phase of Stacked Two-Dimensional Rafts of Actin Filaments," Physical Review Letters 91, 018103 (2003). Copyright (2003) by the American Physical Society.)

Another related reference:
John C. Butler, Thomas Angelini, Jay X. Tang, and Gerard C. L. Wong, Ion Multivalence and Like-Charge Polyelectrolyte Attraction, Phys. Rev. Lett. 91, 028301 (2003)

Associated Physics News Update (available by August 22, 2003)

Associated Physics Review Focus article