Partially methylated derivatives of agar or agarose were prepared by m
ethylating an agar or agarose with various levels of natural methylati
on in alkaline solution with dimethyl sulfate. The resultant derivativ
es were analysed for methylation pattern, gel setting temperature, and
gel strength. The extent to which the gelling temperature was lowered
was proportional to the level of methylation at the 2-position of the
D-galactosyl residues. Since the 2-hydroxyl group on the D-galactose
is the only hydroxyl group which has a binding function in the double
helix model, this observation is strongly supportive of this model of
agarose gels.