Input and data for "Simulating precursor steps for fibril formation in methylcellulose solutions"

We use coarse-grained molecular dynamics simulations to study the precursor steps for fibril formation
in methylcellulose solutions. Simulations of ring stacking between two collapsed methylcellulose chains
demonstrate the existence of a capture radius that is much larger than that predicted by polymer diffusion alone.
When two rings are in very close proximity, they stack together to form a fibril precursor. Simulations of stacks
of such rings suggest that this structure is metastable. In contrast, chains that are within the capture radius but not
in close proximity, as well as for systems containing both ringlike and relaxed chains, fibril-like structures form
via a distinctly different mechanism. Irrespective of their initial arrangement, the chains undergo two specific
conformational changes: (i) a part of either a ring or a randomly coiled chain splays out and (ii) the splayed chain
subsequently engulfs a nearby chain if it is within a certain capture distance. The latter results are consistent
with recent experimental measurements of fibril formation by short methylcellulose chains, which suggests the
formation of a twisted bundle.