Structure of HIV-1 protease in complex with potent inhibitor KNI-272 determined by neutron crystallography

Adachi, Motoyasu; Ohara, Takashi   ; Kurihara, Kazuo; Tamada, Taro; Honjo, Eijiro*; Okazaki, Nobuo; Arai, Shigeki; Shoyama, Yoshinari*; Matsumura, Hiroyoshi*; Adachi, Hiroaki*; Takano, Kazufumi*; Mori, Yusuke*; Hidaka, Koshi*; Kimura, Toru*; Hayashi, Yoshio*; Kiso, Yoshiaki*; Kuroki, Ryota

To understand the catalytic mechanism of HIV-1 protease, we have determined the crystal structure of HIV-1 protease in complex with a transition state mimetic inhibitor, KNI-272 by neutron crystallography. Our results indicates that the carbonyl group of allophenylnorstatine in KNI-272 forms a significant hydrogen bond with protonated Asp 25, and the hydrogen atom from the hydroxyl group of allophenylnorstatine forms a remarkable hydrogen bond with the deprotonated Asp125. These results show direct evidence that Asp25 provides a proton to carbonyl group of substrate and Asp125 contributes to activate the attacking water molecule as a nucleophile.