Isolation and characterization of type I antifreeze proteins from Atlanticsnailfish (Liparis atlanticus) and dusky snailfish (Liparis gibbus)

Antifreeze proteins (AFPs) were isolated from the blood plasma of Atlantic snailfish Liparis atlanticus and dusky snailfish Liparis gibbus, which belo ng to the Teleost family Cyclopteridae. a close relative of sculpins. Using a combination of gel filtration chromatography and reversed-phase HPLC, pr oteins were purified to individual peaks. Atlantic snailfish plasma contain ed two different proteins (MW=9344, 9415) while dusky snailfish plasma cont ained five protein isoforms (MW = 951-9814), as determined by mass spectrom etry. Further characterization revealed that these proteins are rich in ala nine (> 50 mol%), and have a-helical secondary structure that can undergo r eversible thermal denaturation. Thermal hysteresis activities of these prot eins were similar to each other but lower than the major type I AFPs from w inter flounder. Results of this study have indicated that although the AFPs from snailfish are significantly larger than previously described type I A FPs, they share enough characteristics to be classified in this group. (C) 2001 Elsevier Science B.V. All rights reserved.