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Ester Carbonyl Vibration as a Sensitive Probe of Protein Local Electric Field
Author(s) -
Pazos Ileana M.,
Ghosh Ayanjeet,
Tucker Matthew J.,
Gai Feng
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201402011
Subject(s) - hydrogen bond , electric field , dielectric , chemistry , chemical physics , amino acid , aspartic acid , vibration , peptide , glutamic acid , molecule , materials science , nanotechnology , organic chemistry , physics , optoelectronics , acoustics , biochemistry , quantum mechanics
The ability to quantify the local electrostatic environment of proteins and protein/peptide assemblies is key to gaining a microscopic understanding of many biological interactions and processes. Herein, we show that the ester carbonyl stretching vibration of two non‐natural amino acids, L ‐aspartic acid 4‐methyl ester and L ‐glutamic acid 5‐methyl ester, is a convenient and sensitive probe in this regard, since its frequency correlates linearly with the local electrostatic field for both hydrogen‐bonding and non‐hydrogen‐bonding environments. We expect that the resultant frequency–electric‐field map will find use in various applications. Furthermore, we show that, when situated in a non‐hydrogen‐bonding environment, this probe can also be used to measure the local dielectric constant ( ε ). For example, its application to amyloid fibrils formed by Aβ 16–22 revealed that the interior of such β‐sheet assemblies has an ε value of approximately 5.6.