The effects of percentage water content in DMSO/water mixtures on amyl
ose conformation were measured by following changes in specific optica
l rotation,limiting viscosity number, and C-13-NMR chemical shifts. Th
e temperature dependence of specific optical rotation showed differenc
es in amylose conformation for four ratios of dimethyl suphoxide/water
. The changes in limiting viscosity of amylose in different proportion
s of DMSO/water with increasing temperature, and the effect of tetrame
thylurea on the specific rotation of amylose, indicate that the number
of intramolecular hydrogen bonds decreases with increased water conte
nt. An amylose conformational change was also deduced from C-13-NMR ch
emical shift changes. Thirty-three percent water appears to be a cross
over concentration, above which the helical conformation is progressiv
ely lost with increased temperature. With further increase in water co
ntent to 66.6%, transition to a random coil conformation is complete,
and iodine complexation may take place. The transition of amylose conf
ormation from helix to loose helix to random coil with increasing wate
r content was deduced from the experimental results.