Pramanik B, Tsarbopoulos A, Labdon J E, Czarniecki M, Nagabhushan T L, Trotta P P
Schering Corporation, Bloomfield, New Jersey 07003.
Biochem Biophys Res Commun. 1988 Dec 15;157(2):836-43. doi: 10.1016/s0006-291x(88)80325-5.
The nonapeptide Cys-Tyr-Cys-Gln-Asp-Pro-Tyr-Val-Lys was prepared by solid-phase peptide synthesis under oxidizing conditions. Fast atom bombardment mass spectrometric analysis of the untreated molecule produced an ion consistent with a structure involving an intramolecular disulfide bond between Cys(1) and Cys(3). Mass spectra of the peptide after treatment with 2-mercaptoethanol gave signals corresponding to the reduced disulfide form of the peptide and to a mixed disulfide of the peptide with 2-mercaptoethanol. Molecular mechanics calculations of the conformation of the 11-membered ring formed by disulfide bond closure predicted a discrete, low-energy structure resembling the locus of a gamma turn. We hypothesize that this structure may be important in the recognition and cleavage of the signal sequence of the parent molecule.
九肽Cys-Tyr-Cys-Gln-Asp-Pro-Tyr-Val-Lys是在氧化条件下通过固相肽合成法制备的。对未经处理的分子进行快速原子轰击质谱分析，产生了一个与涉及Cys(1)和Cys(3)之间分子内二硫键的结构一致的离子。用2-巯基乙醇处理后的肽的质谱给出了与肽的还原二硫键形式以及肽与2-巯基乙醇的混合二硫键相对应的信号。对由二硫键闭合形成的11元环构象进行分子力学计算，预测出一种离散的、低能量结构，类似于γ转角的轨迹。我们推测这种结构可能在亲本分子信号序列的识别和切割中起重要作用。
