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Conformational aspects of polypeptide structure. XLI. Crystal structure of S ‐thiazolidine‐4‐carboxylic acid and helical structure of poly[( S )‐thiazolidine‐4‐carboxylic acid]
Author(s) -
Goodman Murray,
Chen Vera,
Benedetti Ettore,
Pedone Carlo,
Corradini Paolo
Publication year - 1972
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.1972.360110903
Subject(s) - thiazolidine , chemistry , carboxylic acid , oxazolidine , stereochemistry , crystal structure , crystallography , polymer chemistry
The helical structures of poly[( S )‐thiazolidine‐4‐carboxylic acid], in the cis and trans forms, were redetermined by using the new sets of bond angles and bond lengths established by X‐ray diffraction analysis of L ‐thioproline. Calculations of the helical structures of poly‐ L ‐proline and poly[( S )‐oxazolidine‐4‐carboxylic acid] were also repeated. As a result of these energy calculations, it is suggested that, in contrast to poly‐ L ‐proline and poly[( S )‐oxazolidine‐4‐carboxylic acid], poly[( S )‐thiazolidine‐4‐carboxylic acid] should not mutarotate from the trans to the cis form. This result is due to the fact that the energy barrier for the conversion is most likely too high. Previous experimental work is consistent with this finding.