Folding studies of the helical structure of hNPY【15-29】 by CD and 1H-NMR

• Main Authors: Hui-Mei Tsai, 蔡慧美
• Other Authors: Chang-Shin Lee
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/25810177374269249843

碩士 === 淡江大學 === 化學學系碩士班 === 96 === Human neuropeptide Y (hNPY) has a well-defined alpha-helical structure in solution, and is monomer at low concentration, but is dimer at high concentration. It has specific binding mechanism : First, the monomer structure binds with membrane micelle, and further interacts with G-protein coupled receptors (GPCRs). We probe into the folding conformation of hNPY【15-29】in difference solvent condition, 100％ H2O and 50％ TFE / 50％ H2O by CD and 2D NMR experiment. Chemical shift index (CSI) of 1H and 13C were acquired after finishing assignments of 2D NMR spectroscopy of COSY, TOCSY, NOESY, and [13C, 1H]-HSQC. By using CSI, we can predict the secondary structure of hNPY【15-29】. NOE distance constraints were determined from NOESY spestra. We used XPLOR for structure calculations, including molecular dynamics simulation annealing and energy-minimized process. Twenty refined hNPY【15-29】conformations were resulted from structure simulation. We use PFG-NMR to estimate the dissociation and self-association of hNPY【15-29】in aqueous TFE. Also, we investigate whether or not hNPY【15-29】has intramolecular hydrogen bond by performing hydrogen /deuterium exchange experiment. Combination of CD, 2D NMR, and structure calculations, PFG-NMR, we assured that hNPY【15-29】assumes not only a conformation of random coil but also other regular secondary structure in 100％ H2O; assumes a monomeric and alpha-helical structure in 50％ TFE / 50％ H2O. At lower temperature, the structure of hNPY【15-29】is more compact while at higher temperature, it is more flexible.