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Complex formation with alkali and alkaline earth metal ions of cyclic octapeptides, cyclo(Phe‐Pro) 4 , cyclo(Leu‐Pro) 4 , and cyclo[Lys(Z)‐Pro] 4
Author(s) -
Kimura Shunsaku,
Imanishi Yukio
Publication year - 1983
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.360221106
Subject(s) - chemistry , acetonitrile , alkali metal , alkaline earth metal , alcohol , solvent , metal , cyclic peptide , metal ions in aqueous solution , medicinal chemistry , inorganic chemistry , stereochemistry , ion , crystallography , peptide , organic chemistry , biochemistry
Complex formation with alkali and alkaline earth metal ions of cyclic octapeptides, cyclo(Phe‐Pro) 4 , cyclo(Leu‐Pro) 4 , and cyclo[Lys(Z)‐Pro] 4 was investigated in relation to conformation. In an alcohol solution, cyclo(Phe‐Pro) 4 did not form complexes. However, cyclo(Leu‐Pro) 4 and cyclo[Lys(Z)‐Pro] 4 formed complexes selectively with Ba 2+ and Ca 2+ ions. Changing the solvent from alcohol to acetonitrile, the complexation behavior was very different. In acetonitrile, cyclo(Phe‐Pro) 4 was found to form a complex with Ba 2+ , and CD spectra of cyclo(Leu‐Pro) 4 and cyclo[Lys(Z)‐Pro] 4 changed sharply on complexation with K + . Rate constants of the complex formation between the cyclic octapeptides and metal salts were in the range of 0.7–12 L mol −1 min −1 in an alcohol solution. One of the two types of complex formation in acetonitrile was much faster than that in an alcohol solution.