Neutron crystal structure analysis of HIV-1 protease

Adachi, Motoyasu

To understand the mechanism of interaction between HIV-1 protease and its inhibitor KNI-272, we have determined the crystal structure of HIV-1 protease in complex with KNI-272. For neutron crystallography of protein, it is needed to prepare large crystals in size using much amount of purified protein. We have used synthesized DNA optimized to express in E. coli and have purified refolded HIV-1 protease by reverse phase chromatography finally. The diffraction data were collected using BIX-4 at JRR-3 in JAEA. The structure was refined by program PHENIX. Our results indicates that the carbonyl group of allophenylnorstatine (Apns) in KNI-272 forms a significant hydrogen bond with protonated Asp 25, and the hydrogen atom from the hydroxyl group of Apns forms a remarkable hydrogen bond with the deprotonated Asp125. These results show direct evidence that Asp125 provides a proton to carbonyl group of substrate and Asp25 contributes to activate the attacking water molecule as a nucleophile.