Taluja Ajay, Bae You Han
Department of Pharmaceutics & Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah, USA.
Pharm Res. 2007 Aug;24(8):1517-26. doi: 10.1007/s11095-007-9270-z. Epub 2007 Mar 24.
This study is to investigate whether poly(ethylene glycol) (PEG)-b-poly(L-histidine) [PEG-polyHis] can reduce aggregation of insulin in aqueous solutions on agitation by forming ionic complexes.
Insulin aggregation on agitation was monitored spectrophotometrically and by fibrillation studies with a dye Thioflavin T. Pluronic F-127 as a control and PEG-polyHis as a novel multifunctional excipient were added to prevent destabilization of insulin. Conformation of insulin was evaluated in a circular dichroism (CD) study.
Ionic interactions between insulin and PEG-polyHis were induced in the pH range: 5.5-6.5. pH 5.5 was selected for further evaluation based on particle size/zeta potential studies. Ionic complexation with PEG-polyHis is more effective at pH 5.5 in stabilizing insulin (75% of insulin retained versus 0% with no excipient) than Pluronic F-127 (42% retained). PEG-polyHis guards against insulin aggregation in non-complexing pH conditions (pH 7.4), 64% insulin retained versus 58% with F-127 and 0% with no excipient) pointing to the potential role played by PEG in modulation of insulin surface adsorption. Rate of fibrillation was higher for plain insulin compared with addition of PEG-polyHis and Pluronic F-127 at both pH.
Understanding and manipulation of such polyelectrolyte-protein complexation will likely play a role in protein stabilization.
本研究旨在调查聚（乙二醇）（PEG）-b-聚（L-组氨酸）[PEG-聚组氨酸]是否能通过形成离子复合物来减少胰岛素在水溶液中搅拌时的聚集。
通过分光光度法监测胰岛素在搅拌时的聚集情况，并使用硫黄素T进行纤维化研究。添加普朗尼克F-127作为对照，PEG-聚组氨酸作为新型多功能辅料，以防止胰岛素失稳。通过圆二色性（CD）研究评估胰岛素的构象。
在pH范围5.5 - 6.5内诱导了胰岛素与PEG-聚组氨酸之间的离子相互作用。基于粒径/ζ电位研究，选择pH 5.5进行进一步评估。在pH 5.5时，与PEG-聚组氨酸形成离子复合物在稳定胰岛素方面比普朗尼克F-127更有效（75%的胰岛素得以保留，而无辅料时为0%）（42%得以保留）。在非络合pH条件（pH 7.4）下，PEG-聚组氨酸可防止胰岛素聚集（64%的胰岛素得以保留，而F-127为58%，无辅料时为0%），这表明PEG在调节胰岛素表面吸附方面发挥了潜在作用。在两个pH值下，普通胰岛素的纤维化速率均高于添加PEG-聚组氨酸和普朗尼克F-127后的情况。
对这种聚电解质 - 蛋白质络合的理解和操控可能在蛋白质稳定化中发挥作用。
