Studies of a putative ice‐binding motif in winter flounder skin‐type anti‐freeze polypeptide

Winter flounder contains two distinct anti‐freeze protein isoforms, which are the liver‐type extracellular anti‐freeze proteins and the skin‐type intracellular anti‐freeze protein. The skin‐type anti‐freeze proteins exhibit lower anti‐freeze activities than the liver‐type isoforms and this might be due to their lacking complete ice‐binding motifs. One of the skin‐type anti‐freeze proteins, skin‐type anti‐freeze protein‐3, does contain putative overlapping ice‐binding motifs with the sequences ‘‐K—DT‐’ and ‘‐DT–K‐’. Synthetic anti‐freezes containing 0–3 repeats of the ‘‐DT–K‐’ motif were tested for stability and activity. Loss of the single ‘‐DT–K‐’ of skin‐type anti‐freeze protein‐3 increases the anti‐freeze activity and increasing the number of motifs to two or three lowers the activity. The decrease in activity with an increasing frequency of the motif correlates with a decrease in the helical content of these peptides at 0°C.

Studies of a putative ice‐binding motif in winter flounder skin‐type anti‐freeze polypeptide Journal Articles