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Conformation of poly(γ‐glutamic acid) in aqueous solution
Author(s) -
Muroga Yoshio,
Nakaya Asami,
Inoue Atsuki,
Itoh Daiki,
Abiru Masaya,
Wada Kaori,
Takada Masako,
Ikake Hiroki,
Shimizu Shigeru
Publication year - 2016
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.22776
Subject(s) - chemistry , random coil , aqueous solution , glutamic acid , circular dichroism , potentiometric titration , salt (chemistry) , titration , crystallography , stereochemistry , amino acid , organic chemistry , biochemistry , ion
Local conformation and overall conformation of poly(γ‐DL‐glutamic acid) (PγDLGA) and poly(γ‐L‐glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by 1 H‐NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random‐coil in a range of ε > ε * , where ε * is about 0.3, 0.35, 0.45, and 0.5 for added‐salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε < ε * , however, ε dependence of their overall conformation is significantly differentiated from each other. PγDLGA tends to aggregate intramolecularly and/or intermolecularly with decreasing ε, but PγLGA still behaves as expanded random‐coil. It is speculated that spatial arrangement of adjacent carboxyl groups along the backbone chain essentially affects the overall conformation of PγGA in acidic media. © 2015 Wiley Periodicals, Inc. Biopolymers 105: 191–198, 2016.