EFFECT OF A SINGLE ASPARTATE ON HELIX STABILITY AT DIFFERENT POSITIONS IN A NEUTRAL ALANINE-BASED PEPTIDE
EFFECT OF A SINGLE ASPARTATE ON HELIX STABILITY AT DIFFERENT POSITIONS IN A NEUTRAL ALANINE-BASED PEPTIDE
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DOI：
10.1002/pro.5560021006
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发表时间：
1993-10-01
期刊：
影响因子：
8
通讯作者：
BALDWIN, RL
中科院分区：
文献类型：
--
作者：
HUYGHUESDESPOINTES, BMP;SCHOLTZ, JM;BALDWIN, RL
将单个天冬氨酸残基放置在丙氨酸为电中性参照肽的不同位置，并用圆二色谱测量了这些多肽的螺旋含量。多肽螺旋含量与天冬氨酸位置的依赖关系已被用来确定螺旋倾向(S值)。天冬氨酸残基的带电形式(Asp-)和未带电形式(Asp_0)都是强螺旋断裂剂，在0℃时具有相同的S值0.29。Asp-与螺旋偶极的相互作用影响整个螺旋位置的螺旋稳定性，不仅在相互作用稳定螺旋的N末端附近，而且在相互作用破坏稳定的C末端附近。比较了酸性pH(Asp0)和中性pH(Asp-)下的螺旋含量，发现电荷-螺旋偶极相互作用随着氯化钠浓度的增加而缓慢地被屏蔽，即使在4.8M的氯化钠溶液中也不能完全屏蔽。最后，发现谷氨酰胺与天冬氨酸之间存在螺旋稳定的氢键相互作用(间距i，i+4)。这种侧链相互作用对谷氨酰胺和天冬氨酸残基的取向和间距都是特异的，并且对氯化钠筛选具有抵抗力。
A single aspartate residue has been placed at various positions in individual peptides for which the alanine-based reference peptide is electrically neutral, and the helix contents of the peptides have been measured by circular dichroism. The dependence of peptide helix content on aspartate position has been used to determine the helix propensity (s-value). Both the charged (Asp-) and uncharged (Asp0) forms of the aspartate residue are strong helix breakers and have identical s-values of 0.29 at 0-degrees-C. The interaction of Asp- with the helix dipole affects helix stability at positions throughout the helix, not only near the N-terminus, where the interaction is helix stabilizing, and the C-terminus, where it is destabilizing. Comparison of the helix contents at acidic pH (Asp0) and at neutral pH (Asp-) shows that the charge-helix dipole interaction is screened slowly with increasing NaCl concentration, and screening is not complete even at 4.8 M NaCl. Lastly, a helix-stabilizing hydrogen-bond interaction between glutamine and aspartate (spacing i, i + 4) has been found. This side-chain interaction is specific for both the orientation and spacing of the glutamine and aspartate residues and is resistant to screening by NaCl.