Antifreeze proteins from snow mold fungi

The psychrophilic fungi Coprinus psychromorbidus and Typhula ishikariensis produced unique antifreeze proteins (AFPs) in the extracellular space. Molecular masses of purified fungal AFPs of C psychromorbidus and T ishikariensis were approximately 22 and 23 kDa, respectively. Cloned genes of AFPs from T ishikariensis do not have any similarity with known proteins. Purified fungal AFPs from cultural filtrate of T ishikariensis and recombinant fungal AFP from methylotrophic yeast formed specific ice crystals resembling Stone Age knives. These observations indicate that fungal AFPs do not form proper hexagonal ice crystals to inhibit their growth and that fungal AFPs can probably bind to surfaces of ice crystals in an irregular manner.