Heitz A, Chiche L, Le-Nguyen D, Castro B
Centre de Biochimie Structurale, CNRS-INSERM, Faculté de Pharmacie, Université Montpellier I, Montpellier, France.
Eur J Biochem. 1995 Nov 1;233(3):837-46. doi: 10.1111/j.1432-1033.1995.837_3.x.
A peptide, corresponding to the entire sequence of the squash trypsin inhibitor EETI II (Ecballium elaterium trypsin inhibitor) in which the six cysteines, engaged in three disulphide bridges in native EETI II, have been replaced by six serines, has been synthesised. CD, Fourier-transform infrared spectroscopy (FTIR) and 1H-NMR studies of this peptide revealed that some secondary structures present in native EETI II are still populated in the absence of disulphide bonds. Native-like secondary structures were observed for segments 10-15 (helix), 16-19 and 22-25 (reverse turns) but no native tertiary interaction was detected. However, a non-native local interaction between the aromatic ring of Phe26 and the amide group of Gly28 was observed. It is hypothesised that the 10-15, 16-19 and 22-25 native-like local conformations could play a major role in the early folding of EETI II.
已合成一种肽，其对应于南瓜胰蛋白酶抑制剂EETI II（喷瓜胰蛋白酶抑制剂）的完整序列，其中天然EETI II中参与形成三个二硫键的六个半胱氨酸已被六个丝氨酸取代。对该肽进行的圆二色光谱（CD）、傅里叶变换红外光谱（FTIR）和1H-NMR研究表明，在没有二硫键的情况下，天然EETI II中存在的一些二级结构仍然存在。在10 - 15片段（螺旋）、16 - 19片段和22 - 25片段（反向转角）中观察到类似天然的二级结构，但未检测到天然的三级相互作用。然而，观察到苯丙氨酸26的芳香环与甘氨酸28的酰胺基团之间存在非天然的局部相互作用。据推测，10 - 15、16 - 19和22 - 25类似天然的局部构象可能在EETI II的早期折叠中起主要作用。
