Densities of glycylglycine in sucrose-water mixed solvent have been measured at 288.15, 298.15 and 308.15 K by Anton Paar DMA55 vibrating-tube digital densimeter. The apparent molar volume VΦ, limiting partial molar volume , partial molar volumes of transfer Δtrs from water to sucrose-water mixed solvent and the hydration numbers Nh for glycylglycine have been calculated. The transfer volumes from water to sucrose-water mixed solvent and hydration numbers have been discussed in terms of the cosphere overlap model. The results show that a dominant structura1 interaction between the charged centers of glycylglycine and sucrose gives positive contribution to the transfer volume. The partial molar volumes of transfer of glycylglycine are positive, and increase with increasing sucrose concentration; while the hydration numbers decrease with increasing temperature and sucrose concentration. The limiting partial molar volume increases with increasing temperature, and partial molar volumes of transfer depend less on temperature.

Key words: glycylglycine, sucrose, limiting partial molar volume, partial molar volume of transfer