Isolation and characterization of a novel antifreeze protein from carrot (Daucus carota)

A modified assay for inhibition of ice recrystallization which allows unequ ivocal identification of activity in plant extracts is described. Using thi s assay a novel, cold-induced, 36 kDa antifreeze protein has been isolated from the tap root of cold-acclimated carrot (Daucus carota) plants, This pr otein inhibits the recrystallization of ice and exhibits thermal-hysteresis activity. The polypeptide behaves as monomer in solution and is N- glycosy lated, The corresponding gene is unique in the carrot genome and induced by cold, The antifreeze protein appears to be localized within the apoplast.