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The precipitation of poly‐ L ‐glutamic acid. I. α‐Precipitation
Author(s) -
Zimmerman S. S.,
Mandelkern L.
Publication year - 1975
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.1975.360140311
Subject(s) - precipitation , chemistry , nucleation , aqueous solution , glutamic acid , atmospheric temperature range , crystallography , thermodynamics , amino acid , biochemistry , organic chemistry , meteorology , physics
Studies have been made of the precipitation of poly‐ L ‐glutamic acid from dilute aqueous solutions, over the pH range where the α‐helical conformation is maintained. The major purpose is to establish the molecular conformation in the precipitate and to outline the mechanism of the precipitation. Utilizing molecular‐weight fractions, it is shown that there are two distinctly different precipitation regions, which depend on temperature, concentration, and pH. In one of these regions, the α‐region, a variety of physical properties demonstrate that precipitation occurs without any conformational change. The temperature coefficient of the precipitation process in this region indicates that it is nucleation‐controlled.