Weak alignment of biomacromolecules in collagen gels: an alternative way to yield residual dipolar couplings for NMR measurements.

Collagen, consisting of glycine, proline, and hydroxyproline, is a fibrous protein that can form a rope-like left-hand triple helix structure. It is demonstrated here that the collagen gels prepared from polymerization in the magnetic field can provide weak alignment for protein. The alignment order induced by collagen gels is quite small when compared to other alignment media, but the magnitude of the dipolar couplings can be easily scaled up by increasing the initial concentration of collagen. The collagen gels showed good pH and detergent tolerance. These advantages of collagen gels make it a promising candidate for the alignment of large biomolecules or membrane protein-detergent complexes in the magnetic field.