Urry D W, Chang D K, Krishna N R, Huang D H, Trapane T L, Prasad K U
Biopolymers. 1989 Apr;28(4):819-33. doi: 10.1002/bip.360280404.
Two-dimensional nuclear Overhauser enhancement (2D NOESY) data are reported for the polypentapeptide of elastin, poly(VPGVG), and the cyclopentadecapeptide, cyclo(VPGVG)3. In both, the repeating type II Pro2-Gly3 beta-turn can be derived from the NOE data, providing confirmation of many previous studies. In addition, other through-space connectivities are detailed that also compare favorably with previously determined crystal and solution structures for cyclo(VPGVG)3. Also, near identical data for the cyclopentadecapeptide and the polypentapeptide demonstrate the cyclic conformation-linear (helical) conformational correlate relationship between the two molecules. The 2D NOESY experiment is seen to be an effective means of establishing the presence or absence of a conformational relationship between a cyclic repeating sequence and its higher molecular weight linear counterpart. This is an approach of substantial practical value when developing the conformation of sequential polypeptides and when attempting to identify the presence of the conformation of a repeating peptide sequence within a more complex primary structure. Having established the basic conformational relationship between a cyclic conformation and its linear helical counterpart, cross peaks present in the linear helical structure that are not present in the cyclic conformational correlate can provide information on the interactions between adjacent turns of the helix. In this connection, a Val gamma CH3 in equilibrium Pro beta CH2 interaction is reported that can be the basis for determining the number of pentamers per turn of helix once it is determined whether it is dominantly the Val1 or Val4 gamma CH3 that is interacting with the Pro2 beta CH2.
报道了弹性蛋白的聚五肽（聚（VPGVG））和环十五肽（环（VPGVG）3）的二维核Overhauser增强（2D NOESY）数据。在这两种肽中，重复的II型Pro2-Gly3β-转角均可从NOE数据推导得出，这证实了许多先前的研究。此外，还详细描述了其他空间连接，这些连接也与先前确定的环（VPGVG）3的晶体结构和溶液结构相符。而且，环十五肽和聚五肽几乎相同的数据证明了这两种分子之间的环状构象-线性（螺旋）构象相关关系。二维NOESY实验被认为是确定环状重复序列与其更高分子量线性对应物之间构象关系是否存在的有效手段。当研究连续多肽的构象以及试图在更复杂的一级结构中鉴定重复肽序列构象的存在时，这是一种具有重要实际价值的方法。在确定了环状构象与其线性螺旋对应物之间的基本构象关系后，线性螺旋结构中存在而环状构象对应物中不存在的交叉峰可以提供有关螺旋相邻转角之间相互作用的信息。在这方面，报道了缬氨酸γ-CH3与脯氨酸β-CH2之间的平衡相互作用，一旦确定是主要是缬氨酸1还是缬氨酸4的γ-CH3与脯氨酸2的β-CH2相互作用，这可以作为确定每圈螺旋中五聚体数量的基础。
