Optimal interstrand bridges for collagen-like biomaterials.

In some natural collagen triple helices, cysteine (Cys) residues on neighboring strands are linked by disulfide bonds, enhancing association and maintaining proper register. Similarly, Cys-Cys disulfide bridges have been used to impose specific associations between collagen-mimetic peptides (CMPs). Screening a library of disulfide linkers in silico for compatibility with collagen identifies the disulfide bridge between proximal homocysteine (Hcy) and Cys as conferring much greater stability than a Cys-Cys bridge, but only when Hcy is installed in the Xaa position of the canonical Xaa-Yaa-Gly repeat and Cys is installed in the Yaa position. Experimental evaluation of CMPs that host alternative thiols validates this design: only Hcy-Cys bridges improve triple-helical structure and stability upon disulfide-bond formation. This privileged linker can enhance CMP-based biomaterials and enable previously inaccessible molecular designs.