A REEXAMINATION OF THE DOUBLE-HELIX MODEL FOR AGAROSE GELS USING OPTICAL-ROTATION

The diffuse x-ray diffraction patterns of agarose gels are compatible with both the ''chicken-wire'' gel model consisting of associated doub le-helix chain conformations and a network of more extended, but unent wined helices. Preference for the double-helix model has largely reste d on an early interpretation of optical rotation data. Applying a rece nt, less empirical, chiroptical model of saccharide rotation, we confi rm the earlier analysis by concluding that the rotation observed in th e gel can be satisfactorily accounted for in terms of wide-diameter ag arose helices, capable of intertwining. In addition, we have found tha t the extended helices found in dried sols do not yield the observed g el rotations. (C) 1995 John Wiley & Sons, Inc.