Premium
Poly( L ‐valine). Conformational dependence on the degree of polymerization: Infrared studies
Author(s) -
Itoh Koichi,
Fasman Gerald D.
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.1975.360140815
Subject(s) - chemistry , polymerization , valine , degree of polymerization , polymer chemistry , alanine , infrared spectroscopy , monomer , stereochemistry , amino acid , polymer , organic chemistry , biochemistry
The infrared spectra of poly( L ‐valine)'s with varying degrees of polymerization have been investigated, as well as copolymers of L ‐alanine and L ‐valine. The spectra of nujol mulls of various molecular‐weight poly( L ‐valine)'s, isolated directly from the polymerization media, as well as spectra of these same samples after treatment with strong acid, are recorded. In the 700–250‐cm −1 region, bands at 543 and 414 cm −1 are found to increase with increasing degree of polymerization in the nujol mulls, but are missing in the acid‐treated samples. These bands are assigned to the L ‐valine residues with an β‐helixlike local conformation. It is inferred that the polymerization proceeds initially in the β form, and after a critical degree of polymerization the chains adopt an appreciable amount of an α‐helixlike local conformation.