Caged and clustered structures of endothelin inhibitor BQ123, cyclo(-D-Trp-D-Asp(-)-Pro-D-Val-Leu-)center dot Na+, forming five and six coordination bonds between sodium ions and peptides

Citation
M. Doi et al., Caged and clustered structures of endothelin inhibitor BQ123, cyclo(-D-Trp-D-Asp(-)-Pro-D-Val-Leu-)center dot Na+, forming five and six coordination bonds between sodium ions and peptides, ACT CRYST D, 57, 2001, pp. 628-634
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry & Analysis
Journal title
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
ISSN journal
0907-4449 → ACNP
Volume
57
Year of publication
2001
Part
5
Pages
628 - 634
Database
ISI
SICI code
0907-4449(200105)57:<628:CACSOE>2.0.ZU;2-#
Abstract
BQ123 is a cyclic pentapeptide and a potent endothelin-1 inhibitor. The cry stal structure of the BQ123 sodium salt was determined as the first example of an endothelin inhibitor. Four independent molecules and many solvent mo lecules were found in the asymmetric unit; the total weight was about 3000 Da. The precise structure including the solvent molecules was determined us ing high-resolution data collected on a synchrotron source. Sodium ions for med unique structures with five and six coordination bonds and their forms were distinguished into three classes. An ion was sandwiched by two BQ123 m olecules. This peptide-sodium (2:1) complex showed a cage-like structure an d octahedral coordination was observed. Sodium ions also formed a cluster c omposed of hydrated water molecules and peptides. Two sodium ions were cont ained in this cluster, making five coordination bonds. Despite having the s ame coordination numbers, these ions were distinguishable by differences in the polyhedra. One was trigonal bipyramidal (having six planes) and the ot her was square pyramidal (having five planes). Both shapes were very simila r to each other, although the synchrotron data clearly revealed slight geom etrical differences.