Lee Ting-Wai, Cherney Maia M, Huitema Carly, Liu Jie, James Karen Ellis, Powers James C, Eltis Lindsay D, James Michael N G
Canadian Institute of Health Research Group in Protein Structure and Function, Department of Biochemistry, University of Alberta, Edmonton, Alta., Canada T6G 2H7.
J Mol Biol. 2005 Nov 11;353(5):1137-51. doi: 10.1016/j.jmb.2005.09.004. Epub 2005 Sep 27.
The main peptidase (M(pro)) from the coronavirus (CoV) causing severe acute respiratory syndrome (SARS) is one of the most attractive molecular targets for the development of anti-SARS agents. We report the irreversible inhibition of SARS-CoV M(pro) by an aza-peptide epoxide (APE; k(inact)/K(i) = 1900(+/-400) M(-1) s(-1)). The crystal structures of the M(pro):APE complex in the space groups C2 and P2(1)2(1)2(1) revealed the formation of a covalent bond between the catalytic Cys145 S(gamma) atom of the peptidase and the epoxide C3 atom of the inhibitor, substantiating the mode of action of this class of cysteine-peptidase inhibitors. The aza-peptide component of APE binds in the substrate-binding regions of M(pro) in a substrate-like manner, with excellent structural and chemical complementarity. In addition, the crystal structure of unbound M(pro) in the space group C2 revealed that the "N-fingers" (N-terminal residues 1 to 7) of both protomers of M(pro) are well defined and the substrate-binding regions of both protomers are in the catalytically competent conformation at the crystallization pH of 6.5, contrary to the previously determined crystal structures of unbound M(pro) in the space group P2(1).
导致严重急性呼吸综合征（SARS）的冠状病毒（CoV）的主要肽酶（M（pro））是开发抗SARS药物最具吸引力的分子靶点之一。我们报道了一种氮杂肽环氧化物（APE；k（inact）/K（i）= 1900（±400）M⁻¹ s⁻¹）对SARS-CoV M（pro）的不可逆抑制作用。在空间群C2和P2₁2₁2₁中M（pro）：APE复合物的晶体结构揭示了肽酶的催化性半胱氨酸145的S（γ）原子与抑制剂的环氧化物C3原子之间形成了共价键，证实了这类半胱氨酸肽酶抑制剂的作用模式。APE的氮杂肽成分以类似底物的方式结合在M（pro）的底物结合区域，具有出色的结构和化学互补性。此外，空间群C2中未结合的M（pro）的晶体结构表明，M（pro）两个原体的“N指”（N端残基1至7）定义明确，并且在6.5的结晶pH下，两个原体的底物结合区域处于催化活性构象，这与先前在空间群P2₁中确定的未结合M（pro）的晶体结构相反。
