β-Type Amyloidlike Fibrils of Poly-l-glutamic Acid Convert into Long, Highly Ordered Helices upon Dissolution in Dimethyl Sulfoxide.

Replacing water with dimethyl sulfoxide (DMSO) completely reshapes the free-energy landscapes of solvated proteins. In DMSO, a powerful hydrogen-bond (HB) acceptor, formation of HBs between backbone NH groups and solvent is favored over HBs involving protein's carbonyl groups. This entails a profound structural disruption of globular proteins and proteinaceous aggregates (e.

Effects of terminal capping on the fibrillation of short (L-Glu) peptides.

Several homopolypeptides including poly-l-glutamic acid (PLGA) form amyloid-like fibrils under favorable physicochemical conditions. We have shown recently that even short uncapped (Glu) peptides (for n>3) form fibrillar β-aggregates which cross-seed with amyloid fibrils obtained from high molecular weight fractions of PLGA. Here we investigate effects of N-terminal acetylation and C-terminal amidation on the amyloidogenic tendencies of (Glu) peptides containing 3, 4, and 5 residues.

Beware of Cocktails: Chain-Length Bidispersity Triggers Explosive Self-Assembly of Poly-L-Glutamic Acid β2-Fibrils.

Chain-length polydispersity is among the least understood factors governing the fibrillation propensity of homopolypeptides. For monodisperse poly-L-glutamic acid (PLGA), the tendency to form fibrils depends of the main-chain length. Long-chained PLGA, so-called (Glu)200, fibrillates more readily than short (Glu)5 fragments.