CRYSTALLOGRAPHIC ENZYMOLOGY OF [[omega]]-AMINO ACID PYRUVATE AMINOTRANSFERASE. S. Ikemizu, K.Sasaki¹, N.Watanabe², K. Yonaha³, N. Sakabe & K.Sakabe⁴. Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki, 305 Japan; ¹College of Medical Technology, Nagoya Univ., Higashi, Nagoya, 461 Japan; ²PF, KEK, Tsukuba, Ibaraki, 305 Japan; ³Dept. of Agricultural Chem, Univ. of the Ryukyus, Nishihara, Okinawa, 903-01 Japan; ⁴Dept. of Chemistry, Nagoya Univ. Chikusa, Nagoya, 464 Japan

Many enzyme reaction mechanisms has been established with the crystal structures of enzyme and enzyme-inhibitor complexes. However synchrotron radiation brought the progress of time-resolved protein crystallography. Thus we have to think about that the structure determination of enzyme is the starting point of the time resolved crystallography. Namely the crystal structure of substrate-enzyme complex should be determined in addition to those of inhibitor-complexbecause former complex can transfer to next reaction state but the latter complex can not do. On the other hand, in many reactions the solvent has also very important role of the reaction. Therefore high resolution structure determination is also necessary to study a time resolved protein crystallography. We determined crystal structure of [[omega]]-aminoacid pyravate aminotransferase containing PLP and PMP as a co-factor, substrate-enzyme complexes with [[beta]]-alanine, L-alanine, [[gamma]]-aminobutyric acid, 6-aminohexonate, isoamylamine and pyruvate at better than 1.8Å resolution and we could obtain atomic parameters including solvent molecules. The reaction mechanism on the bases of these structures as been proposed. The application to time resolved Laue method has been testing.