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 degrees C.
Hospital for Sick Children and the Department of Laboratory Medicine, University of Toronto, Ont., Canada.
Q
Q
Lin
K V
KV
Ewart
D S
DS
Yang
C L
CL
Hew
D000818:Animals; D021301:Antifreeze Proteins; D002942:Circular Dichroism; D005432:Flounder; D005615:Freezing; D006023:Glycoproteins / Q000737:chemistry*; D007053:Ice; D010446:Peptide Fragments; D017433:Protein Structure, Secondary; D020449:Repetitive Sequences, Amino Acid; D012867:Skin
D021301:Antifreeze Proteins; D006023:Glycoproteins; D007053:Ice; D010446:Peptide Fragments