Diffusion NMR studies on fish antifreeze proteins and synthetic analogues.
Pulsed field gradient spin echo NMR spectroscopy was used to measure diffusion coefficients of the alpha-helical type I antifreeze protein from the winter flounder, two synthetic derivatives in which the four Thr residues were replaced with Val and Ala, respectively, and the low molecular weight fraction antifreeze glycoprotein. Under the conditions studied, the natural type I antifreeze protein and low molecular weight glycoprotein gave diffusion values that were consistent with the presence of monomeric protein in solution. While significant aggregation of the Ala analogue was observed (2-10 mM), there was no evidence for aggregation in the Val analogue (1-3 mM). These results are compared with previously reported solubility and thermal hysteresis data and the implications for the design of synthetic antifreeze proteins are discussed.
Inglis
Steven R
SR
School of Chemistry, The University of New South Wales, Sydney, NSW 2052, Australia.
McGann
Matthew J
MJ
Price
William S
WS
Harding
Margaret M
MM
D000595:Amino Acid Sequence; D000818:Animals; D021322:Antifreeze Proteins, Type I / Q000138:chemical synthesis* / Q000737:chemistry*; D004058:Diffusion; D029941:Fish Proteins / Q000737:chemistry*; D005399:Fishes; D009682:Magnetic Resonance Spectroscopy; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary
D021322:Antifreeze Proteins, Type I; D029941:Fish Proteins