CRYSTALLIZATION AND PRELIMINARY X-RAY STUDIES OF AZURIN-I AND AZURIN-II FROM DENITRIFING BACTERIUM ALCALIGENS XYLOSOXIDANS GIFU 1051. Chunmin Li*, Tsuyoshi Inoue*, Masaharu Gotowda*, Kazuyuki Hamada*, Nobuya Nishio*, Shinichiro Suzuki^**, Kazuya Yamaguchi^**, and Yasushi Kai*. *Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita 565, ^**Department of Chemistry, Faculty of Science, Osaka University, Toyonaka 560, Japan.

Azurins are the small copper-containing proteins that function as electron transfer agents in the redox systems of some bacteria. It has been known for a long time that only one azurin is obtained from one species of bacteria, except for the case of Methylomonas J. Recently, two azurins were found instead of the single previously identified one in both Alcaligenes xylosoxidans NCIB 11015 and GIFU 1051. Here we present our recent work on the crystallization and preliminary X-ray studies of Azurin-I and Azurin-II from Denitrifing Bacterium Alcaligenes Xylosoxidans GIFU 1051. Both azurins were crystallized by the hanging drop vapor diffusion method at 20*C. The crystals of azurin-I belong to the monoclinic crystal system and have space group C2 with unit cell parameters of a=130.6Å, b=54.4Å, c=74.7Å, and b=96.1*. Four molecules are in the asymmetric unit. The crystals of azurin-II belong to the tetragonal crystal system and have space group P4₁22 with unit cell parameters a=b=52.6Å, c=100.7Å. Only one molecule is in the asymmetric unit. They diffract up to 2.8Å and 2.0Å resolutions, respectively. Their crystal structures were solved by molecular replacement method using AMoRe in the CCP4. Molecular structure of Azurin II from Alcaligenes Xylosoxidans NCIB 11015 was chosen as a starting model for both azurins. The refinement for both azurins is being carried out by XPLOR.