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Conformations of poly‐ L ‐valine in solution
Author(s) -
Epand Raquel F.,
Scheraga Harold A.
Publication year - 1968
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.1968.360061104
Subject(s) - chemistry , valine , circular dichroism , monomer , glycine , optical rotatory dispersion , amino acid , aqueous solution , dimer , residue (chemistry) , copolymer , stereochemistry , polymer , polymer chemistry , organic chemistry , biochemistry
Abstract In order to test theoretical predictions that poly‐ L ‐valine can exist in an α‐helical conformation, water‐soluble block copolymers of L ‐valine and D , L ‐lysine were prepared. By carrying out the synthesis on a resin support (with the use of N ‐carboxyanhydrides) contamination of the individual blocks by any unreacted monomer from the previous block was avoided. A single glycine residue was incorporated at the C‐terminus of the chain for use in amino acid analyses. Using optical rotatory dispersion and circular dichroism criteria, about 50% of the short valine block of ( D , L ‐lysine HCl) 18 ‐( L ‐valine) 15 ‐( D , L ‐lysine‐HCl)1 6 ‐glycine was found to be in the right‐handed α‐helical conformation in 98% aqueous methanol, in water, the polymer appears to be a dimer, with the valine block being involved in the formation of an intermolecular β‐structure.