Vígh R, Cser L, Kilár F, Simon I
Institute of Enzymology, Hungarian Academy of Sciences, Budapest.
Arch Biochem Biophys. 1989 Nov 15;275(1):181-4. doi: 10.1016/0003-9861(89)90362-7.
X-ray diffraction studies show that the diferric (holo) forms of human serum transferrin and lactoferrin have almost the same conformation in crystal. In solution, however, the two proteins exhibit different characteristics. The differences are even more pronounced in the apo forms. Small-angle X-ray and neutron scattering data show that lactoferrin is less compact, in apo and holo forms, than the corresponding forms of transferrin in solution. The comparison of primary structures of the two proteins suggests that one of the interdomain hinge regions is significantly longer in lactoferrin than its counterpart in transferrin. The difference in flexibility due to the long hinge region in lactoferrin may be responsible for many of the differences in the physicochemical characteristics of the two proteins.
X射线衍射研究表明，人血清转铁蛋白和乳铁蛋白的二价铁（全）形式在晶体中具有几乎相同的构象。然而，在溶液中，这两种蛋白质表现出不同的特性。在脱辅基形式中，差异更为明显。小角X射线和中子散射数据表明，乳铁蛋白无论是脱辅基形式还是全形式，在溶液中都比相应形式的转铁蛋白结构更松散。两种蛋白质一级结构的比较表明，乳铁蛋白中一个结构域间铰链区比转铁蛋白中的对应区域长得多。乳铁蛋白中长铰链区导致的柔韧性差异可能是这两种蛋白质许多理化特性差异的原因。
