Temperature sensitive polymers

poly-N-isopropyl acrylamides (PNIPAAm) with different molecular weights

were prepared by radical polymerization．The molecular weight distribution and lower critical solution temperature of these polymers were deter mined by GPC and spectrophotometry．The feasibility of the polymer in assisting the refolding of denatured lysozyme was examined

by directly diluting the denatured lysozyme into refolding buffer containing PNIPAAm of different molecular weight．PNIPAAm with the mean molecular weight of 22

000 (M_ PNIPAAm) showed the best function of assisting lysozyme refolding

as indicated by the recovery of lysozyme activity from the denatured lysozyme sample．The molecular interaction of PNIPAAm with lysozyme and its implication on the structure change of lysozyme were investigated by fluorescence emission spectroscopy．The effects of lysozyme concentration and temperature on the lysozyme refolding were examined and the synergy of urea and M_ PNIPAAm on lysozyme refolding was identified．The suitable temperature for lysozyme refolding was chosen according to the temperature responsive behavior of PNIPAAm. The results shown by present study showed the high potential of temperature sensitive polymers in high concentration protein refolding in vitro in large scale．