Furey W F, Robbins A H, Clancy L L, Winge D R, Wang B C, Stout C D
Science. 1986 Feb 14;231(4739):704-10. doi: 10.1126/science.3945804.
The anomalous scattering data from five Cd in the native protein were used to determine the crystal structure of cadmium, zinc (Cd,Zn) metallothionein isoform II from rat liver. The structure of a 4-Cd cluster was solved by direct methods. A 2.3 A resolution electron density map was calculated by iterative single-wavelength anomalous scattering. The structure is folded into two domains. The amino terminal domain (beta) of residues 1 to 29 enfolds a three-metal cluster of one Cd and two Zn atoms coordinated by six terminal cysteine thiolate ligands and three bridging cysteine thiolates. The carboxyl terminal domain (alpha) of residues 30 to 61 enfolds a 4-Cd cluster coordinated by six terminal and five bridging cysteine thiolates. All seven metal sites have tetrahedral coordination geometry. The domains are roughly spherical, and the diameter is 15 to 20 A; there is limited contact between domains. The folding of alpha and beta is topologically similar but with opposite chirality. Redundant, short cysteine-containing sequences have similar roles in cluster formation in both alpha and beta.
利用天然蛋白质中五个镉的反常散射数据来确定大鼠肝脏中镉、锌（Cd,Zn）金属硫蛋白同工型II的晶体结构。通过直接法解析了一个4-Cd簇的结构。通过迭代单波长反常散射计算出分辨率为2.3 Å的电子密度图。该结构折叠成两个结构域。1至29位残基的氨基末端结构域（β）包裹着一个由六个末端半胱氨酸硫醇盐配体和三个桥连半胱氨酸硫醇盐配位的一个镉和两个锌原子的三金属簇。30至61位残基的羧基末端结构域（α）包裹着一个由六个末端和五个桥连半胱氨酸硫醇盐配位的4-Cd簇。所有七个金属位点都具有四面体配位几何结构。这些结构域大致呈球形，直径为15至20 Å；结构域之间的接触有限。α和β的折叠在拓扑上相似，但手性相反。冗余的、含半胱氨酸的短序列在α和β的簇形成中具有相似的作用。
