CHARGED HISTIDINE AFFECTS ALPHA-HELIX STABILITY AT ALL POSITIONS IN THE HELIX BY INTERACTING WITH THE BACKBONE CHARGES
CHARGED HISTIDINE AFFECTS ALPHA-HELIX STABILITY AT ALL POSITIONS IN THE HELIX BY INTERACTING WITH THE BACKBONE CHARGES
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DOI：
10.1073/pnas.90.23.11337
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发表时间：
1993-12-01
影响因子：
11.1
通讯作者：
BALDWIN, RL
中科院分区：
文献类型：
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作者：
ARMSTRONG, KM;BALDWIN, RL
为了确定带电荷的组氨酸侧链是否仅在组氨酸接近螺旋的一端时或在其位于中心区域时影响α-螺旋稳定性，我们在两种参考肽的许多位置处取代单个组氨酸残基，并测量螺旋稳定性和组氨酸pK（a）。带电荷的组氨酸残基的位置对0.01 M NaCl中的螺旋稳定性有主要影响：当组氨酸位于3位时，17个残基的肽的螺旋含量为24%，而当组氨酸位于17位时，其螺旋含量为76%。这种依赖性的螺旋含量组氨酸的位置急剧下降，在1 M NaCl，预期counterweight筛选的电荷螺旋偶极相互作用。在内部位置的结果表明，带电组氨酸残基的位置影响在这些位置的螺旋稳定性。出乎意料的高值的螺旋内容被发现时，中性或带电组氨酸是在最后三个C-末端的位置之一，这表明，无论是形式可以稳定一个孤立的螺旋通过氢键的主链CO基团。
To determine whether a charged histidine side chain affects alpha-helix stability only when histidine is close to one end of the helix or also when it is in the central region, we substitute a single histidine residue at many positions in two reference peptides and measure helix stability and histidine pK(a). The position of a charged histidine residue has a major effect on helix stability in 0.01 M NaCl: the helix content of a 17-residue peptide is 24% when histidine is at position 3 compared to 76 % when it is at position 17. This dependence of helix content on histidine position decreases sharply in 1 M NaCl, as expected for counterion screening of the charge-helix dipole interaction. Results at interior positions indicate that the position of a charged histidine residue affects helix stability at these positions. Unexpectedly high values of the helix content are found when either neutral or charged histidine is at one of the last three C-terminal positions, suggesting that either form can stabilize an isolated helix by hydrogen bonding to a main-chain CO group.