多管藻中R－藻蓝蛋自的分离、结晶和初步晶体学研究

ISOLATION, CRYSTALLIZATION AND PRELIMINARY CRYSTALLOGRAPHIC ANALYSIS OF R-PHYCOCYANIN FROM POLYSIPHONIA URCEOLATA

从青岛采集的多管藻（Ｐｏｌｙｓｉｐｈｏｎｉａｕｒｃｅｏｌａｔａ）中分离得到的Ｒ－藻蓝蛋白，在ｐＨ＝７．０的０．０５ｍｏｌ／Ｌ磷酸盐－硫酸铵缓冲液中，使用悬滴气相扩散法获得适合Ｘ光衍射分析用单晶。经Ｂｕｅｒｇｅｒ徘循照相和ＸＲＤ—１００面探测仪分析，Ｒ－藻蓝蛋白晶体属于四方晶系，空间群为Ｐ４１（３）２１２，晶胞参数：ａ＝ｂ＝１３７．５ｃ＝２１８．５α＝β＝γ＝９０°。用等比重梯度柱法测定了晶体和母液的比重分别为１．１９和１．０９。根据分子量与晶胞体积估算，一个不对称单位含有一个分子，推测它的分子聚集态形式为（αβ）３。

The light-havesting pigment-protein complex R-phycocyanin from Polysiphoniaurceolata has ho isolated. Single crystals of R-phycocyanin suitable for X-ray deffractionanalysis have ho grown in phosphate buffer and ammonium sulfate system byhanging drops vapour diffusion method. The crystals belong to tetraginal system with spacegroup The parameters of unit cell are : a=b=137.5A, c=218.5A, α=β=γ=90°. Thedensities measured on the crystals and its mother liquor are 1.19 and 1.09 respectively. There isone molecule in an asymmetric unit.