HYDRATION OF ALPHA-MALTOSE AND AMYLOSE - MOLECULAR MODELING AND THERMODYNAMICS STUDY

Hydration of alpha-maltose and amylose were investigated using molecul ar modelling and thermodynamics methods. The structure and energy of h ydration of three low-energy conformers of alpha-maltose were determin ed by the MM3 molecular mechanics method. The hydration structure was found to be sensitive to the conformation of alpha-maltose and hydrati on numbers 10 or 11 were estimated for the different conformers. Diffe rential scanning calorimetry and thermogravimetric analysis were used to determine the number of water molecules specifically bonded (non-fr eezing water) to amylose and different samples of alpha-maltose. Due t o high crystallinity of alpha-maltose samples, the observed non-freezi ng water content was lower than predicted by molecular modelling. In c ontrast, the experimental number of non-freezing molecules of water pe r D-glucopyranose residue for amorphous amylose (n(h) = 3.8) is in goo d accordance with the value of 3.8 extracted from our calculations.