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Article
Conformations within soluble oligomers and insoluble aggregates revealed by resonance energy transfer
Biopolymers
  • Jyothi L. Digambaranath
  • Loan Dang
  • Monika Dembinska
  • Andrew Vasyluk
  • John M. Finke, University of Washington Tacoma
Publication Date
4-1-2010
Document Type
Article
Abstract
A fluorescently labeled 20-residue polyglutamic acid (polyE) peptide 20 amino acid length polyglutamic acid (E(20)) was used to study structural changes which occur in E(20) as it co-aggregates with other unlabeled polyE peptides. Resonance energy transfer (RET) was performed using an o-aminobenzamide donor at the N-terminus and 3-nitrotyrosine acceptor at the C-terminus of E(20). PolyE aggregates were not defined as amyloid, as they were nonfibrillar and did not bind congo red. Circular dichroism measurements indicate that polyE aggregation involves a transition from alpha-helical monomers to aggregated beta-sheets. Soluble oligomers are also produced along with aggregates in the reaction, as determined through size exclusion chromatography. Time-resolved and steady-state RET measurements reveal four dominant E(20) conformations: (1) a partially collapsed conformation (24 A donor-acceptor distance) in monomers, (2) an extended conformation in soluble oligomers (>29 A donor-acceptor distance), (3) a minor partially collapsed conformation (22 A donor-acceptor distance) in aggregates, and (4) a major highly collapsed conformation (13 A donor-acceptor distance) in aggregates. These findings demonstrate the use of RET as a means of determining angstrom-level structural details of soluble oligomer and aggregated states of proteins.
DOI
10.1002/bip.21324
Version
pre-print, post-print
Citation Information
Jyothi L. Digambaranath, Loan Dang, Monika Dembinska, Andrew Vasyluk, et al.. "Conformations within soluble oligomers and insoluble aggregates revealed by resonance energy transfer" Biopolymers Vol. 93 Iss. 4 (2010) p. 299 - 317
Available at: http://works.bepress.com/john_finke/17/