Kalverda A P, Wymenga S S, Lommen A, van de Ven F J, Hilbers C W, Canters G W
Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, The Netherlands.
J Mol Biol. 1994 Jul 22;240(4):358-71. doi: 10.1006/jmbi.1994.1450.
A three-dimensional solution structure of amicyanin from Thiobacillus versutus has been determined by distance geometry and restrained molecular dynamics. A total of 984 experimentally derived constraints were used for the final refinement (881 distance constraints and 103 dihedral angle constraints). Stereospecific assignments were made for 17 prochiral beta-methylene protons (33%) and the methyl groups of eight valine residues. Fourteen structures were selected to represent the solution structure. They show an average pairwise backbone root-mean-square deviation of 1.19 A. The overall structure can be described as a beta-sandwich, built up of nine beta-strands. The copper atom is located between three loops on one end of the molecule. Two of these loops contribute the copper ligands. His54 is on the loop between beta-strands 4 and 5. The other three ligands, Cys93, His96 and Met99, are located evenly spaced on the loop between beta-strands 8 and 9. This loop is folded in two consecutive type 1 turns with His96 as the donor and acceptor of the NHi-CO(i-3) hydrogen bonds. The folding is reminiscent of the general cupredoxin fold. Considerably different are the large 21 residue N-terminal extension, that is unique to amicyanin and forms an extra beta-strand (strand 1), and the region between beta-strands 5 and 7. The partly surface-exposed copper ligand His96 is surrounded by a hydrophobic patch consisting of seven residues.
运用距离几何学和受限分子动力学方法，已确定了来自氧化亚铁硫杆菌的蓝铜蛋白的三维溶液结构。最终精修共使用了984个实验得出的限制条件（881个距离限制条件和103个二面角限制条件）。对17个前手性β-亚甲基质子（33%）和8个缬氨酸残基的甲基进行了立体专一性归属。选择了14个结构来代表溶液结构。它们的平均成对主链均方根偏差为1.19埃。整体结构可描述为一个由九条β-链组成的β-折叠三明治结构。铜原子位于分子一端的三个环之间。其中两个环提供铜配体。His54位于β-链4和5之间的环上。另外三个配体Cys93、His96和Met99在β-链8和9之间的环上均匀分布。这个环以His96作为NHi-CO(i-3)氢键的供体和受体，折叠成两个连续的1型转角。这种折叠让人联想到一般的铜蓝蛋白折叠。蓝铜蛋白特有的、由21个残基组成的大的N端延伸形成了一条额外的β-链（链1），以及β-链5和7之间的区域，二者有很大不同。部分暴露于表面的铜配体His96被一个由七个残基组成的疏水区域所包围。
