Beltramini M, Bubacco L, Salvato B, Casella L, Gullotti M, Garofani S
Department of Biology, University of Padova, Italy.
Biochim Biophys Acta. 1992 Mar 27;1120(1):24-32. doi: 10.1016/0167-4838(92)90420-i.
The binding of various ligand molecules to the binuclear Cu(I) site of deoxy-hemocyanin has been investigated through the changes produced in the aromatic region of the circular dichroism spectrum of the protein, where a cluster of tryptophan residues located in the vicinity of copper site undergo conformational reorientations in the presence of exogenous ligands coordinated to the metal. In agreement with expectations, the binuclear site of arthropod hemocyanin is severely hindered to the access of exogenous ligands except for very small molecules like CO, O2 or CN- while for mollusc proteins ligands such as thiourea and 2-mercaptoethanol bind easily to the Cu(I) sites. However, the access of the ligand becomes progressively hindered and eventually prevented as the size of substituents on the ligand increases.
通过蛋白质圆二色光谱芳香区产生的变化，研究了各种配体分子与脱氧血蓝蛋白双核Cu(I)位点的结合情况。在该区域，位于铜位点附近的一簇色氨酸残基，在与金属配位的外源配体存在时会发生构象重排。正如预期的那样，节肢动物血蓝蛋白的双核位点对外源配体的进入有严重阻碍，除了像CO、O2或CN-这样的非常小的分子；而对于软体动物蛋白，硫脲和2-巯基乙醇等配体很容易与Cu(I)位点结合。然而，随着配体上取代基尺寸的增加，配体的进入逐渐受到阻碍，最终被阻止。
