Hydrogen exchange kinetics of surface peptide amides in bovine pancreatic trypsin inhibitor.
Hydrogen exchange kinetics of surface peptide amides in bovine pancreatic trypsin inhibitor.
复制标题
牛胰蛋白酶抑制剂表面肽酰胺的氢交换动力学。
DOI：
10.1016/0022-2836(87)90359-7
复制
发表时间：
1987
影响因子：
5.6
通讯作者：
Woodward,C
中科院分区：
文献类型：
--
作者：
Tüchsen,E;Woodward,C
本文测定了牛胰胰蛋白酶抑制剂25种快速质子交换的酸碱催化速率常数kH、obsKOH和最小速率pH值pHmin。在这里，我们报告的标记程序giving 1H核磁共振光谱分辨率的7个额外的快速交换NH质子和pH值的依赖性，他们的化学位移。给出了Ala 16、Gly 28和Arg 53 NH基团的kH、obs、KOH、obs和pHmin值，这些基团是晶体结构中静态可及性大于零的仅有的骨架酰胺质子，而Gly 56 NH则埋在α-螺旋的C末端。本文报告的所有四个质子的pH min ≥3。先前的研究的结论预测，肽质子的pH值高于那些模型化合物具有更大的肽O比肽N原子的静态可及性。在晶体结构中的位置的四个NH基团，其交换率在这里报告的定性与这些预测一致。Ala 16在pH 5.5时的离子强度依赖性表明，随着盐浓度的降低，交换速率急剧增加，正如在正静电场中碱催化交换所预期的。
The acid and base catalytic rate constants,kH,obsandKOH, obsand the pH at the minimum rate, pHmin, of 25 rapidly exchanging protons in bovine pancreatic trypsin inhibitor have been determined. Here we report the labeling procedure giving1H nuclear magnetic resonance spectral resolution of seven additional rapidly exchanging NH protons and the pH dependence of their chemical shifts. Values ofkH,obs,KOH, obsand pHminare given for Ala16, Gly28 and Arg53 NH groups, the only backbone amide protons with static accessibility of more than zero in the crystal structure not previously reported, and for Gly56 NH, buried at the C terminus of an α-helix. All four protons reported here have pHmin≥3. Conclusions of the previous study predict that peptide protons with pHminhigher than those of model compounds have greater static accessibility of the peptide O than of the peptide N atom. The locations in the crystal structure of the four NH groups whose exchange rates are reported here are in qualitative agreement with these predictions. The ionic strength dependence of Ala16 at pH 5.5 shows a sharp increase in the exchange rate with decreasing salt concentration, as expected for base-catalyzed exchange in a positive electrostatic field.