Wemmer D, Kallenbach N R
Biochemistry. 1983 Apr 12;22(8):1901-6. doi: 10.1021/bi00277a025.
A two-dimensional (2-D) Fourier-transform nuclear magnetic resonance (NMR) study of the 18 amino acid neurotoxin apamin isolated from honeybee venom is reported. Combining 2-D J-correlated spectra with 2-D nuclear Overhauser spectra in H2O solution permits essentially complete assignment of the 1H NMR spectrum of apamin at a fixed pH, including a number of spin systems that are reported for the first time. The structural model previously derived by Bystrov et al. [Bystrov, V. F., Okhanov, V. V., Miroshnikov, A. I., & Ovchinnikov, Yu. A. (1980) FEBS Lett. 119, 113-116] from NMR data is shown to be largely correct. The 2-D nuclear Overhauser effect (NOE) spectrum in particular reveals a series of amide-amide NOE's consistent with an alpha-helical core (residues 9-15) in the molecule. NOE's between amide and C alpha protons, followed by amide to amide NOE's, indicate a beta-turn involving residues 3-5 and a nonstandard turn including residues 6-8. We find no evidence for the beta-type structure postulated at the C terminus, however. Instead, it appears that the alpha-helix continues with increasing fraying from residues 16-18.
报道了对从蜂毒中分离出的18氨基酸神经毒素蜂毒明肽的二维（2-D）傅里叶变换核磁共振（NMR）研究。在H2O溶液中将二维J相关光谱与二维核Overhauser光谱相结合，能够在固定pH值下基本完成蜂毒明肽1H NMR光谱的归属，包括一些首次报道的自旋系统。先前由Bystrov等人[Bystrov, V. F., Okhanov, V. V., Miroshnikov, A. I., & Ovchinnikov, Yu. A. (1980) FEBS Lett. 119, 113 - 116]根据NMR数据推导的结构模型在很大程度上是正确的。特别是二维核Overhauser效应（NOE）光谱揭示了一系列与分子中α-螺旋核心（残基9 - 15）一致的酰胺-酰胺NOE。酰胺与Cα质子之间的NOE，随后是酰胺与酰胺之间的NOE，表明存在涉及残基3 - 5的β-转角和包括残基6 - 8的非标准转角。然而，我们没有发现C末端假定的β型结构的证据。相反，似乎α-螺旋从残基16 - 18开始继续，且逐渐松散。
