Self-assembly of a peptide Boc-(IIe)5-OMe in chloroform and N,N-dimethylformamide
Self-assembly of a peptide Boc-(IIe)5-OMe in chloroform and N,N-dimethylformamide
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DOI：
10.1021/la990004l
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发表时间：
2000-02-22
期刊：
影响因子：
3.9
通讯作者：
Scibioh, MA
中科院分区：
文献类型：
--
作者：
Jayakumar, R;Murugesan, M;Scibioh, MA
五肽Boc-（Ile）（5）-OMe（1）在氯仿和N，N-二甲基甲酰胺（DMF）中发生有序聚集。肽在氯仿和DMF中以高浓度形成凝胶。在CHCl 3和DMF中的肽凝胶的扫描电子显微镜（SEM）研究揭示了直径为100 nm的原纤维的存在。在DMF中形成的凝胶中，发现该基本单元经历组装成松散放置的原纤维。在氯仿中，纤维之间存在不同直径（600至1800纳米）的周期性筛。肽1还在氯仿中形成胶束聚集体。用8-苯胺基-1-萘磺酸（ANS）荧光技术和诱导圆二色性（ICD）光谱技术测定了肽在氯仿中的临界胶束浓度（cmc）。用ANS和氯化十六烷基吡啶（CPC）分别作为外部荧光探针和猝灭剂，用静态荧光猝灭法测定了该肽在氯仿中的聚集数为6 +/- 1。如通过凝胶渗透色谱（GPC）技术获得的，发现肽在N，N-二甲基甲酰胺中的聚集数为13 +/-1。肽的傅里叶变换红外（FTIR）光谱显示聚集体中没有游离的NH，这意味着分子间氢键的形成是聚集体形成的主要驱动力。在CHCl 3和DMF中形成的肽凝胶的圆二色性（CD）光谱显示存在平行的β-折叠构象。热力学参数，如Δ G（m）度、Δ H（m）度和Δ S（m）度似乎证实了肽中氢键合的β-折叠样聚集体的形成。
Ordered aggregation of pentapeptide Boc-(Ile)(5)-OMe (1) was observed in chloroform and N,N-dimethylformamide (DMF). The peptide formed a gel in both chloroform and DMF at high concentrations. Scanning electron microscopic (SEM) studies of the peptide gel in CHCl3 and DMF revealed the presence of fibrils of 100 nm in diameter. In the gel formed in DMF, this fundamental unit was found to undergo assembly into loosely placed fibrils. In chloroform, periodic sieves of varied diameter (between 600 and 1800 nm) are found between the fibers. Peptide 1 also forms micellar aggregates in chloroform. The critical micellar concentration (cmc) of the peptide in chloroform was determined by the 8-anilino-1- naphthalenesulfonic acid (ANS) fluorescence technique and induced circular dichroic (ICD) spectral technique using ANS. The aggregation number of the peptide in chloroform was found to be 6 +/- 1, as determined by a static fluorescence quenching method using ANS and N-cetylpyridinium chloride (CPC) as external fluorescent probe and quencher, respectively. The aggregation number of the peptide was found to be 13 +/- 1 in N,N-dimethylformamide as obtained by a gel permeation chromatographic (GPC) technique. The Fourier transform infrared (FTIR) spectrum of the peptide shows no free NH in the aggregate, implying that intermolecular hydrogen bond formation is the main driving force for aggregate formation. The circular dichroism (CD) spectra of the peptide gels formed in CHCl3 and DMF show the presence of a parallel beta-sheet conformation. Thermodynamic parameters, such as Delta G(m)degrees", Delta H(m)degrees, and Delta S(m)degrees appear to substantiate the hydrogen bonded beta-sheet-like aggregate formation in the peptide.