STRUCTURE-ANALYSIS OF PROTEINS BY A COMBINATION OF DISTANCE GEOMETRY CALCULATION AND H-1-NMR CHEMICAL-SHIFT CALCULATION

A new method for protein structure determination in solution has been proposed by a combination of distance geometry calculation (DADAS90) and H-1 NMR chemical shift calculation for proteins. When the ring current shielding effect from the aromatic ring in protein on an alpha-CH proton is larger than 0.3 ppm, the distance constraints from the aromatic rings to the alpha-CH protons are incorporated into the process of DADAS calculation using the co-ordinates from the X-ray diffraction analysis. A better structure for BPTI (Basic Pancreatic Trypsin Inhibitor) with a good correlation between calculated and observed alpha-CH chemical shifts, and with a small value of the target function, is obtained by taking into accountsuch a ring-current shielding effect.