A conformational study of agarose by vacuum UV CD.

Agarose films were prepared using a variety of casting conditions, heat treatments, and solvation treatments. Films represented the high temperature sol, the room temperature gel, and a high temperature state with cross-links intact. The vacuum uv CD of the film samples varies considerably, but the similarities between the film CD and the previously reported solution CD show that dehydration per se does not affect the CD. Combining the CD results for the dried sol with the x-ray results of Foord and Atkins leads to a description of the high temperature sol in terms of locally extended chain conformations. The CD of the gel and its peculiarly high uv absorption are satisfactorily, albeit not uniquely, interpreted in terms of the double-helix model of the gel, in agreement with previous conformational studies based on chiroptical properties.