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Laser Raman studies of conformational variations of poly‐ L ‐lysine
Author(s) -
Yu TainJen,
Lippert Joseph L.,
Peticolas Warner L.
Publication year - 1973
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.1973.360120919
Subject(s) - chemistry , amide , lysine , raman spectroscopy , crystallography , ionic bonding , helix (gastropod) , ionization , transition (genetics) , ionic strength , laser , stereochemistry , amino acid , ion , organic chemistry , biochemistry , optics , aqueous solution , ecology , physics , snail , gene , biology
The frequencies and intensities of the laser Raman spectra of poly‐ L ‐lysine (PLL) have been observed in the following studies: (1) the thermally induced α‐to‐β transition which occurs with increasing temperature at high pH; (2) the ionized form to α transition at 10°C by increasing pH; and (3) the ionized form to α transition by ionic strength at low pH. The frequency‐dependent bands which have been observed are the amide I (in H 2 O), amide I′ (in D 2 O), amide III, and C–C stretch. It has been found possible to assign an unique set of frequencies and intensities to each conformation of PLL of α, β, and ionized form. In this way the nature of the conformations intermediate in the transitions can be determined. The frequencies of the amide III and amide III′ are very weak in the α‐helix and somewhat higher than usual in the β form. Hence it appears the amide III and amide III′ bands may differ from one type of polypeptide to another with the same backbone conformation.