Conformations within soluble oligomers and insoluble aggregates revealed by resonance energy transfer.
Biopolymers
; 93(4): 299-317, 2010 Apr.
Article
en En
| MEDLINE
| ID: mdl-19927295
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.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Ácido Poliglutámico
/
Transferencia Resonante de Energía de Fluorescencia
Idioma:
En
Revista:
Biopolymers
Año:
2010
Tipo del documento:
Article
País de afiliación:
Estados Unidos