α-螺旋束蛋白因螺旋偶极而失稳
Destabilization of an alpha-helix-bundle protein by helix dipoles.
作者信息
Gilson M K, Honig B
机构信息
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032.
出版信息
Proc Natl Acad Sci U S A. 1989 Mar;86(5):1524-8. doi: 10.1073/pnas.86.5.1524.
The finite difference Poisson-Boltzmann method is used to calculate the electrostatic work of assembling the four alpha-helices of Themiste dyscritum hemerythrin to form the protein's observed antiparallel helical bundle. The calculations account for the interaction of each helix dipole with the high-dielectric solvent as well as for pairwise interactions of the dipoles with each other. We find that the electrostatic work of assembly is dominated by unfavorable changes in dipole-solvent interactions rather than by favorable interactions between antiparallel helices. Furthermore, the electrostatic energy difference between the observed arrangement of helices in hemerythrin and at least one other possible helical arrangement is less than 1 kT. These results suggest that the helix dipole actually destabilizes the helical bundle and that it plays little or no role in producing the observed bundle geometry.
有限差分泊松-玻尔兹曼方法用于计算拟海豆芽蚯蚓血红蛋白的四个α螺旋组装形成该蛋白质中观察到的反平行螺旋束时的静电功。这些计算考虑了每个螺旋偶极子与高介电常数溶剂的相互作用以及偶极子之间的成对相互作用。我们发现组装的静电功主要由偶极子-溶剂相互作用的不利变化主导，而非反平行螺旋之间的有利相互作用。此外，血红蛋白中观察到的螺旋排列与至少一种其他可能的螺旋排列之间的静电能差小于1kT。这些结果表明螺旋偶极子实际上使螺旋束不稳定，并且在产生观察到的束几何形状方面几乎不起作用或没有作用。
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