Structure and dynamics of the neutrophil defensins NP-2, NP-5, and HNP-1: NMR studies of amide hydrogen exchange kinetics.
The exchange kinetics for the slowly exchanging amide hydrogens in three defensins, rabbit NP-2, rabbit NP-5, and human HNP-1, have been measured over a range of pH at 25 degrees C using 1D and 2D NMR methods. These NHs have exchange rates 10(2) to 10(5) times slower than rates from unstructured model peptides. The observed distribution of exchange rates under these conditions can be rationalized by intramolecular hydrogen bonding of the individual NHs, solvent accessibility of the NHs, and local fluctuations in structure. The temperature dependencies of NH chemical shifts (NH temperature coefficients) were measured for the defensins and these values are consistent with the defensin structure. A comparison is made between NH exchange kinetics, NH solvent accessibility, and NH temperature coefficients of the defensins and other globular proteins. Titration of the histidine side chain in NP-2 was examined and the results are mapped to the three-dimensional structure.
Skalicky
J J
JJ
Department of Chemistry and Biochemistry, University of Colorado-Boulder 80309-0215.
Selsted
M E
ME
Pardi
A
A
D000577:Amides / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry*; D001798:Blood Proteins / Q000737:chemistry*; D023082:Defensins; D006801:Humans; D006859:Hydrogen / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000737:chemistry*; D011487:Protein Conformation; D011522:Protons; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D012997:Solvents; D013045:Species Specificity; D023084:alpha-Defensins
D000577:Amides; D000890:Anti-Infective Agents; D001798:Blood Proteins; D023082:Defensins; D011522:Protons; D012997:Solvents; D023084:alpha-Defensins; C406413:human neutrophil peptide 1; D006859:Hydrogen