Campbell A P, Sykes B D
Department of Biochemistry, University of Alberta, Edmonton, Canada.
J Mol Biol. 1991 Nov 20;222(2):405-21. doi: 10.1016/0022-2836(91)90219-v.
We have used two-dimensional 1H nuclear magnetic resonance spectroscopy to determine the structure of the synthetic inhibitory peptide N alpha-acetyl TnI(104-115) amide bound to calcium-saturated skeletal troponin C (TnC). Conformational changes in the peptide induced by the formation of the troponin I (TnI) peptide-TnC complex were followed by the study of the transferred nuclear Overhauser effect, a technique that allows one to determine the structure of a ligand bound to a macromolecule. The structure of the bound TnI peptide reveals an amphiphilic alpha-helix, distorted around the two central proline residues. The central bend in the peptide functions to bring the residues on the hydrophobic face into closer proximity with each other, thereby forming a small hydrophobic pocket. The hydrophilic, basic residues extend off the opposite face of the peptide. Hydrophobic surfaces on TnC that become exposed upon binding of calcium are involved in the binding of the TnI peptide, but electrostatic interactions also contribute to the strength of the interaction. The role of amphiphilic helices in the targeting of calcium-binding proteins such as troponin C will be discussed.
我们利用二维¹H核磁共振光谱法来确定与钙饱和的骨骼肌肌钙蛋白C（TnC）结合的合成抑制性肽Nα-乙酰基肌钙蛋白I（104-115）酰胺的结构。通过研究转移核Overhauser效应来追踪肌钙蛋白I（TnI）肽-TnC复合物形成过程中肽的构象变化，这是一种能够确定与大分子结合的配体结构的技术。结合态TnI肽的结构显示出一个两亲性α-螺旋，在两个中心脯氨酸残基周围发生扭曲。肽中的中心弯曲作用是使疏水面上的残基彼此更靠近，从而形成一个小的疏水口袋。亲水性碱性残基从肽的相对面伸出。TnC上在结合钙后暴露的疏水表面参与了TnI肽的结合，但静电相互作用也有助于增强这种相互作用。我们将讨论两亲性螺旋在靶向钙结合蛋白（如肌钙蛋白C）中的作用。
