کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5371819 1503971 2008 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The kinetics of aggregation of poly-glutamic acid based polypeptides
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
The kinetics of aggregation of poly-glutamic acid based polypeptides
چکیده انگلیسی

The aggregation of two negatively-charged polypeptides, poly-L-glutamic acid (PE) and a copolymer of poly-glutamic acid and poly-alanine (PEA), has been studied at different peptide and salt concentrations and solution pH conditions. The kinetics of aggregation were based on Thioflavin T (ThT) fluorescence measurements. The observed lag phase shortened and the aggregation was faster as the pH approached the polypeptides' isoelectric points. While the initial polypeptide structures of PE and PEA appeared identical as determined from circular dichroism spectroscopy, the final aggregate morphology differed; PE assumed large twisted lamellar structures and the PEA formed typical amyloid-like fibrils, although both contained extensive β-sheet structure. Differences in aggregation behavior were observed for the two polypeptides as a function of salt concentration; aggregation progressed more slowly for PE and more quickly for PEA with increasing salt concentration. Several models of aggregation kinetics were fit to the data. No model yielded consistent rate constants or a critical nucleus size. A modified nucleated polymerization model was developed based on that of Powers and Powers [E.T. Powers, D.L. Powers, The kinetics of nucleated polymerizations at high concentrations: Amyloid fibril formation near and above the “supercritical concentration”, Biophys. J. 91 (2006) 122-132], which incorporated the ability of oligomeric species to interact. This provided a best fit to the experimental data.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biophysical Chemistry - Volume 136, Issues 2–3, August 2008, Pages 74-86
نویسندگان
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