Merkel J S, Sturtevant J M, Regan L
Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208114, New Haven, CT 06520-8114, USA.
Structure. 1999 Nov 15;7(11):1333-43. doi: 10.1016/s0969-2126(00)80023-4.
Both backbone hydrogen bonding and interactions between sidechains stabilize beta sheets. Cross-strand interactions are the closest contacts between the sidechains of a beta sheet. Here we investigate the energetics of cross-strand interactions using a variant of the B1 domain of immunoglobulin G (IgG) binding protein G (beta1) as our model system.
Pairwise mutations of polar and nonpolar residues were made at a solvent-exposed site between the two central parallel beta strands of beta1. Both stabilizing and destabilizing interactions were measured. The greatest stabilizations were observed for charge-charge interactions. Our experimental study of sidechain interactions correlates with statistical preferences: residue pairs for which we measure stabilizing interaction energies occur together frequently, whereas destabilizing pairs are rarely observed together.
Sidechain interactions modulate the stability of beta sheets. We propose that cross-strand sidechain interactions specify correct strand register and ordering through the energetic benefit of optimally arranged pairings.
主链氢键和侧链间相互作用均能稳定β折叠。跨链相互作用是β折叠中侧链间最紧密的接触。在此，我们使用免疫球蛋白G（IgG）结合蛋白G（β1）的B1结构域变体作为模型系统，研究跨链相互作用的能量学。
在β1的两条中央平行β链之间的溶剂暴露位点进行极性和非极性残基的成对突变。测量了稳定和不稳定相互作用。电荷-电荷相互作用观察到最大的稳定性。我们对侧链相互作用的实验研究与统计偏好相关：我们测量到稳定相互作用能的残基对经常同时出现，而不稳定对很少同时被观察到。
侧链相互作用调节β折叠的稳定性。我们提出，跨链侧链相互作用通过最佳排列配对的能量优势来确定正确的链对齐和排序。
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