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The optical properties of tyrosine‐containing cyclic dipeptides
Author(s) -
Snow Julian W.,
Hooker Thomas M.,
Schellman John A.
Publication year - 1977
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.1977.360160110
Subject(s) - chemistry , dihedral angle , dipeptide , tyrosine , circular dichroism , side chain , crystallography , stereochemistry , amino acid , molecule , organic chemistry , polymer , biochemistry , hydrogen bond
The chiroptical properties of the cyclic dipeptides cyclo ( L ‐alanyl‐ L ‐tyrosine) and cyclo ( L ‐tyrosyl‐ L ‐tyrosine) have been investigated as a function of molecular conformation. Theoretical optical calculations and conformational energy calculations have been carried out as a function of the side‐chain dihedral angles χ 1 and χ 2 , and as a function of the angle of fold of the cyclic dipeptide backbone. The results of these theoretical calculations have been compared with experimental circular dichroism (CD) data. Theoretical predictions are in very good agreement with experiment for c ( L ‐Tyr‐ L ‐Tyr). Agreement was not quite as good for c ( L ‐Ala‐ L ‐Tyr), although the signs of all of the Cotton effects were apparently predicted correctly except for that associated with the lowest energy tyrosine absorption band.