Hydrogen bonding on the ice-binding face of a beta-helical antifreeze protein indicated by amide proton NMR chemical shifts.
The dependence of amide proton chemical shifts on temperature is used as an indication of the hydrogen bonding properties in a protein. The amide proton temperature coefficients of the beta-helical antifreeze protein from Tenebrio molitor are examined to determine their hydrogen bonding state in solution. The temperature-dependent chemical shift behavior of the amides in T. molitor antifreeze protein varies widely throughout the protein backbone; however, very subtle effects of hydrogen bonding can be distinguished using a plot of chemical shift deviation (CSD) versus the backbone amide chemical shift temperature gradient (Deltadelta/DeltaT). We show that differences between the two ranks of ice-binding threonine residues on the surface of the protein indicate that threonine residues in the left-hand rank participate in intrastrand hydrogen bonds that stabilize the flat surface required for optimal ice binding.
Department of Biochemistry, CIHR Group in Protein Structure and Function, and Protein Engineering Network of Centres of Excellence, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
Margaret E
ME
Daley
Steffen P
SP
Graether
Brian D
BD
Sykes
D000577:Amides / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D021301:Antifreeze Proteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D007053:Ice; D019476:Insect Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011522:Protons; D013696:Temperature; D013712:Tenebrio; D013816:Thermodynamics
D000577:Amides; D021301:Antifreeze Proteins; D007053:Ice; D019476:Insect Proteins; D009587:Nitrogen Isotopes; D011522:Protons