PARATHYROID HORMONE

甲状旁腺激素(PTH)一直是众多研究的对象 多年来，由于其在监管中的关键作用， 细胞外钙动态平衡。最近，越来越多的人对 甲状旁腺素和甲状旁腺素衍生激动剂作为骨重建的合成代谢药 作为治疗骨质疏松症的可能候选药物， 有目击证人。从之前的结构调查来看，阿尔法 N-末端和C-末端结构域中的螺旋已经被鉴定。从… 序列截断研究表明，C-末端是 与膜包埋G蛋白偶联的重要结合 受体。考虑到这种螺旋的两亲性，我们建议 这种螺旋的作用是与膜表面相互作用， 在甲状旁腺素多肽的N-末端螺旋上起到锚的作用 激活感受器。为了检验这一假设，我们开始了 一种氨基酸22-31的类似物的研究 由序列E(22)-L-L-E-K-L-L-E-KL(3 1)替换，设计为 模拟一个完美的两亲性α-螺旋，几乎没有序列同源性 在这个地区(两亲性除外)到原生的PTH 荷尔蒙。如果结合区域中的两亲性α-螺旋是 被受体识别的基序，那么修饰应该产生 有效的激动剂。当然，这一结论的前提是 多肽序列中的修饰将是螺旋的。致信地址 在这一点上，开始了对该多肽的核磁共振研究。至 模拟多肽被研究的膜的环境 DPC胶束的存在。在这些条件下，线条宽度 的质子信号被显着展宽，导致甚至 较差的光谱分辨率。正因为如此，甚至不可能 用室内仪器分配质子信号。 允许在750 MHz光谱仪上采集的质子-质子谱 对于所有质子信号的明确分配和 识别了大量的NOE，以前没有解决。这个 化学位移指数和NOES清楚地表明了 螺旋在C-末端和允许一个高的发展 此模拟器的分辨率结构。

Parathyroid hormone (PTH) has been the object of numerous studies for many years now, owing to its crucial role in the regulation of extracellular calcium homeostasis. More recently, a growing interest in PTH and PTH-derived agonists as anabolic agents for bone remodeling and as possible drug candidates for the treatment of osteoporosis has been witnessed. From previous structural investigations, alpha helices in the N-and C-terminal domains have been identified. From sequence truncation studies, the C-terminus has been shown to be important for binding to the membrane embedded G-protein coupled receptor. Given the amphipathic nature of this helix, we proposed that the role of this helix is to interact with the membrane surface, to act as an anchor while the N-terminal helix of the PTH peptide activates the receptor. To examine this hypothesis, we began the investigation of an analog in which the amino acids 22-31 have been substituted by the sequence E(22)-L-L-E-K-L-L-E-KL(3 1), designed to model a perfect amphiphilic alpha-helix, with little sequence homology in this region (other than the amphiphilic nature) to the native PTH hormone. If an amphiphilic alpha-helix in the binding domain is the motif recognized by the receptor, then the modification should produce an effective agonist. Of course, this conclusion presupposes that the modification will be helical within the peptide sequence. To address this point, an NMR investigation of this peptide was initiated. To mimic the environment of the membrane the peptide was investigated in the presence of DPC micelles. Under these conditions the line widths of the proton signals are significantly broadened resulting in even worse spectral resolution. Because of this, it was impossible to even assign the proton signals with the instrumentation in house. Proton-proton spectra collected on the 750 MHz spectrometer allowed for the unambiguous assignment of all of the proton signals and identification of a large number of NOEs, previously unresolved. The chemical shift index and NOEs clearly indicated the presence of a helix in the C-terminus and allowed the development of a high resolution structure of this analog.