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Conformation of ethyl (+)-(2S,3S)-3-{1-[N-(3-methylbutyl)amino]leucylcarbonyl}oxi-rane-2-carboxylate (loxistatin), a cysteine protease inhibitor: X-ray crystallographic and 1H nuclear magnetic resonance studies

1988; Royal Society of Chemistry; Issue: 6 Linguagem: Inglês

10.1039/p29880000851

2050-8239

Toshimasa Ishida, Masaaki Sakaguchi, Daisuke Yamamoto, Masatoshi Inoue, Kunihiro Kitamura, Kazunori Hanada, Takanao Sadatome,

Phytochemistry and biological activities of Ficus species

In order to establish the conformational characteristics of a cysteine protease inhibitor, the crystal and solution conformations of loxistatin have been determined by X-ray crystallographic and 1H n.m.r. spectroscopic analyses. The molecules were arranged in the crystal as a series of infinite parallel β-sheet structures formed via intermolecular N-H ⋯ O hydrogen bonds. The loxistatin molecule has a flattened, curved conformation, which appears to be energetically stable. Similar conformations of loxistatin were also observed in (CD3)2SO and CDCl3 solutions. On the basis of the results obtained, the relation between the conformation of loxistatin and its inhibitory activity was discussed and compared with the stereostructure of the papain–substrate analogue complex.