Effect of environmental conditions on aggregation and fibril formation of barstar

Item Type:	Article
Title:	Effect of environmental conditions on aggregation and fibril formation of barstar
Creators Name:	Gast, K. and Modler, A.J. and Damaschun, H. and Kroeber, R. and Lutsch, G. and Zirwer, D. and Golbik, R. and Damaschun, G.
Abstract:	The dependence on environmental conditions of the assembly of barstar into amyloid fibrils was investigated starting from the nonnative, partially folded state at low pH (A-state). The kinetics of this process was monitored by CD spectroscopy and static and dynamic light scattering. The morphology of the fibrils was visualized by electron microscopy, while the existence of the typical cross-{beta} structure substantiated by solution X-ray scattering. At room temperature, barstar in the A-state is unable to form amyloid fibrils, instead amorphous aggregation is observed at high ionic strength. Further destabilization of the structure is required to transform the polypeptide chain into an ensemble of conformations capable of forming amyloid fibrils. At moderate ionic strength (75 mM NaCl), the onset and the rate of fibril formation can be sensitively tuned by increasing the temperature. Two types of fibrils can be detected differing in their morphology, length distribution and characteristic far UV CD spectrum. The formation of the different types depends on the particular environmental conditions. The sequence of conversion: A-state → fibril type → fibril type II appears to be irreversible. The transition into fibrils is most effective when the protein chain fulfills particular requirements concerning secondary structure, structural flexibility and tendency to cluster.
Keywords:	Barstar, Amyloid Fibril, A-State, Aggregation, Protein Folding, Secondary Structure
Source:	European Biophysics Journal with Biophysics Letters
ISSN:	0175-7571
Publisher:	Springer
Volume:	32
Number:	8
Page Range:	710-723
Date:	December 2003
Official Publication:	https://doi.org/10.1007/s00249-003-0336-5
PubMed:	View item in PubMed

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