INVESTIGATION OF FACTORS CONTRIBUTING TO PARALLEL BETA-SHEET STABILITY

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。β-发夹模型系统已被用于识别对反平行β-折叠稳定性至关重要的几个因素，包括环形成段的构象倾向和相邻链之间的侧链-侧链相互作用。我们感兴趣的是探索影响平行β-折叠稳定性的因素。其中一种多肽是这项工作的重要组成部分。我们已经在我们的INOVA-600上检测了这种多肽，但较差的S/N在许多实验中都存在问题。我们计划检测的另一种多肽是一种由循环约束的β-氨基酸残基组成的β-多肽。对表现出与蛋白质或核酸相似的二级结构行为的非天然低聚物的研究，为影响骨架的“折叠性”的参数提供了新的见解，例如，构象稳定性与残基数量或残基灵活性之间的关系。这种多肽给出了一个特征明确的β-多肽螺旋构象的CD签名，但在我们的Inova 600上进行的2D实验中没有观察到非连续的NOE。我们预计，在冷冻探针上进行的提高的灵敏度将被证明在识别非序列NOE方面是有用的，并为补充CD数据的二级结构提供证据。我们预计对每一种多肽进行TOCSY和ROESY，并对两种多肽中的一种进行HSQC。我们对这两种化合物进行ROESY实验的原因有两个。首先，我们有兴趣检查这些化合物中的非连续NOE，这是由于较差的S/N而不可能的。第二，我们对使用低温探头的ROESY抑制水的能力感到好奇。我们不知道有任何人这样做过。由于较差的S/N，我们也很难在自然丰度下对我们的多肽进行HSQC实验。我们预计使用低温探头将开始解决这个问题。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Beta-hairpin model systems have been used to identify several factors that are crucial to antiparallel beta -sheet stability, including the conformational propensity of the loop-forming segment and sidechain-sidechain interactions between neighboring strands. We are interested in probing the factors that contribute to parallel beta -sheet stability. One of these peptides is an important part of that work. We have examined this peptide on our INOVA-600, but poor S/N has been problematic for many experiments.The other peptide we plan to examine is a beta -peptide comprised of cyclically constrained beta -amino acid residues. The study of unnatural oligomers that display secondary structural behavior analogous to that of proteins or nucleic acids provides new insight on the parameters that influence the "foldability" of a backbone, e.g., the relationships between conformational stability and number of residues or residue flexibility. This peptide gives a characteristic CD signature for a well-characterized beta -peptide helical conformation, but no non-sequential NOEs are observed in the 2D experiments performed on our Inova 600. We expect that the increased sensitivity of experiments performed on the cryoprobe will prove useful in identifying non-sequential NOEs and provide evidence for secondary structure complementary to the CD data.We anticipate running a TOCSY and ROESY on each of the peptides and an HSQC on one of the two peptides. Our reason for running ROESY experiments on both of the compounds is two-fold. First, we are interested in examining non-sequential NOEs in these compounds, which has not been possible due to poor S/N. Second, we are curious about the capability of water suppression with ROESY using the cryoprobe. We are not aware of anyone having done this. HSQC experiments have also been difficult to acquire on our peptides at natural abundance due to poor S/N. We anticipate that using the cryoprobe will begin to resolve this problem.