A possible model for concomitant folding of the GED chain and association by DMSO dilution.

<p>(<b>A</b>) The polar amino acid rich segment of the completely or partially dissociated polypeptide chain of GED monomer have high probability of helix formation due to the electrostatic interaction. The monomeric units come in close proximity of other similar units in the system due to intermolecular charge interactions thereby forming clusters. (<b>B</b>) Helix formation initiates in a certain segment of the C-terminal of the monomer and the nascent helices of the monomers stack together to form barrel like structures. (<b>C</b>) The helix extends in the neighboring segments. The vacuum electrostatic potential surfaces generated by NOC software (<a href="http://noch.sourceforge.net/" target="_blank">http://noch.sourceforge.net/</a>) depict predominance of opposite charges in the segments Lys68 – Glu80 and Asp95 – Lys121, which favors anti-parallel organization of the newly formed helices of the monomeric units to form extended oligomeric units. (<b>D</b>) Helix formation initiates in the N-terminal half of the monomer. However Proline 67 acts as a kink around which the polypeptide chain can bend thereby providing certain degree of flexibility to the N-terminal half. These units simultaneously arrange themselves in a particular orientation such that the N-terminal helices of the monomeric units are not completely embedded in the core of the assembly; rather it has certain degree of flexibility. (<b>E</b>) The N-terminal helix is completely formed and the oligomers arrange themselves linearly in random numbers to form the extended oligomers with a wide diversity of size. (<b>F</b>) Enlarged view of a part of the TEM image of copper plate with ∼1 µM GED in water (inset) at room temperature. The image shows differential size and shape distribution of GED oligomers, although the majority show elongated structures. The concentration of the protein mentioned is not the true concentration due to the evaporation of water during sample preparation.