Cyclic disulfides of cysteinyl-tetraglycyl-cysteine (Ia), cysteinyl-tyrosyl-triglycyl-cysteine (Ib) and cysteinyl-tyrosyl-isoleucyl-diglycyl-cysteine (Ic) were synthesized by classical methods of peptide synthesis. The actions of solvent and of side chains in the positions 2 and 3 on the conformational arrangement of the peptide backbone and the disulfide group were investigated by means of CD spectroscopy. Some mechanisms which co-operate in stabilizing the oxytocin conformation were identified. Hence, it may be deduced, that the amino acid sequence in the positions 1-3 determines the spatial arrangement characteristic for oxytocin, at least in a protonating medium.
半胱
氨酸-四甘
氨酰-半胱
氨酸(Ia)、半胱
氨酸-酪
氨酰-三甘
氨酰-半胱
氨酸(Ib)和半胱
氨酸-酪
氨酰-异亮
氨酰-二甘
氨酰-半胱
氨酸(Ic)的环二
硫化物是通过肽合成的经典方法合成的。通过圆二色谱法研究了溶剂和位置2和3的侧链对肽骨架和二
硫键构象排列的影响。确定了一些在稳定
催产素构象方面起作用的机制。因此,可以推断,在质子化介质中,位置1-3的
氨基酸序列决定了
催产素特征空间排列。