Conformational analysis of a new cyclic depsipeptide calcium blocker, leualacin, by NMR spectroscopy

✍ Scribed by Keiko Yoda; Hideyuki Haruyama; Harumitu Kuwano; Kiyosi Hamano; Kazuhiko Tanzawa

• Book ID: 104204887
• Publisher: Elsevier Science
• Year: 1994
• Tongue: French
• Weight: 635 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)89684-8

✦ Synopsis

Abstmcc The three-dimensional structure of leualacin. a novel calcium channel blocker from Hupsidospma irregulari wBs detemhed in CDCI,. Based upon the dihedral angle constraints from the analysis of $.I,.,,, and '4,. * and the distance constraints deduced from 'H-( 'H) NO& and '%-( 'H) NO&, conformers completely satisfying the NMR data were obtained by the conformational grid search program SYBYL followed by the energy minimization program XF'LOR. Leualacin's structure is characterized by y-and @turn lie moieties analogous to cyclic peptides, which are fixed by trans-annular hydrogen bonds formed between L-leucine and p-alanine. L-N-methylphenylalanine and S-leucic acid were found to be connected by cis peptide bond. The RMSDs (Root Mean Square Differences) calculated for the backbone atoms among four structures are 0.6 A.

The ring current effect caused by the phenylalanine moiety was reproduced by a calculation based on the resulting structures according to Bovey and Johnson's formula.