<br>A链一级结构差异对胰岛素片段聚集的影响,ACS Omega

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A链一级结构差异对胰岛素片段聚集的影响
ACS Omega ( IF 3.7 ) Pub Date : 2018-08-21 00:00:00 , DOI: 10.1021/acsomega.8b00500
Paul P Nakka ₁ , Ke Li ₁ , Daniel Forciniti ₁

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牛胰岛素和人胰岛素具有相似的一级结构。在本文中，对牛胰岛素和人胰岛素的胰岛素 A 链区域的氨基酸组成不同进行了研究。在固相肽合成中合成了牛胰岛素片段（BIF）和人胰岛素片段（HIF）。使用分数阶乘分辨率 III 实验设计研究了 pH、温度、尿素、离子强度和搅拌对原纤维形成的影响。通过荧光和红外光谱以及光学显微镜监测纤维颤动。两种片段在 pH 1.6 和 60 °C 的温度下均形成原纤维。使用二参数动力学模型确定滞后时间和表观聚集生长速率常数。结果发现，牛胰岛素片段的滞后时间比人胰岛素片段短，而 HIF 的指数期速率比 BIF 更快。在两个片段中都观察到β-折叠含量随时间增加。在β-折叠增加之前，α-螺旋最初减少，随后在从滞后期到伸长期的过渡期间中间增加。温度和离子强度是滞后阶段最重要的实验因素之一，而离子强度在两个片段的延伸阶段都被 pH 值取代。刚果红结合证实了富含反平行β-折叠的环状低聚物结构的存在，其倾向于形成富含平行β-折叠的原纤维。

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Effect of Differences in the Primary Structure of the A-Chain on the Aggregation of Insulin Fragments

Bovine and human insulin have similar primary structures. In this article, the region of the insulin A-chain of bovine and human insulin where the amino acid composition is different was studied. Bovine insulin fragment (BIF) and human insulin fragment (HIF) were synthesized in solid-phase peptide synthesis. The effects of pH, temperature, urea, ionic strength, and stirring on the formation of fibrils were studied using a fractional factorial resolution III experimental design. Fibrillation was monitored by fluorescence and infrared spectroscopy and optical microscopy. Both fragments formed fibrils at pH 1.6 and a temperature of 60 °C. The lag time and apparent aggregation growth rate constant were determined using a two-parameter kinetic model. It was found that the bovine insulin fragment has a shorter lag time than the human insulin one, whereas the exponential phase rate was faster for HIF than for BIF. An increase in β-sheets content with time was observed in both fragments. The increase in β-sheets was preceded by an initial decrease in α-helices followed by an intermediate increase during the transition from the lag phase to elongation phase. Temperature and ionic strength are among the most important experimental factors during the lag phase, whereas ionic strength is replaced by pH during the elongation phase for both the fragments. Congo red binding confirmed the presence of ringlike oligomer structures rich in antiparallel β-sheets, which tend to form fibrils rich in parallel β-sheets.

更新日期：2018-08-21

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