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Conformational change of poly‐ N ε ‐glutary‐ L ‐lysine and poly‐ N ε ‐succinyl‐ L ‐lysine in aqueous salt solutions
Author(s) -
Murai Norio,
Sugai Shintaro
Publication year - 1974
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.1974.360130611
Subject(s) - chemistry , potentiometric titration , aqueous solution , salt (chemistry) , lysine , alkali metal , polymer , crystallography , solvent , titration , inorganic chemistry , polymer chemistry , stereochemistry , amino acid , ion , organic chemistry , biochemistry
The conformational changes of poly‐ N ε ‐glutaryl‐ L ‐lysine (PGL) and poly‐ N ε ‐succinyl‐ L ‐lysine (PSL) in various salt solutions were studied by use of ORD and potentiometric titration measurements. The addition of alkali metal salts to the fully ionized PGL or PSL solution caused helix formation. The helical content of the polymers increases in the following sequences: at salt concentration 0–2 M , CsCl < KCl < LiCl < NaCl; and at 2–3 M , LiCl < CsCl < KCl ∼ NaCl. The preferential binding of the solvent components with various alkali metal salts of PGL or PSL was measured in LiCl, NaCl, and KCl solutions by means of equilibrium dialysis and differential refractometry. It was found that with increasing salt concentration, the polymers were preferentially hydrated in NaCl and KCl soultions; however the salt was preferentially bound to the polymers in LiCl solution. Such preferential binding was suggested to be closely related to conformational change. The addition of CaCl 2 to polymer solutions led to the stabilization of the helical structure of PGL or PSL.