title: cis,cis-Ceratospongamide N,N-dimethylacetamide hemisolvate in the presence of twinning.
abstract: Ceratospongamide (CS) is a potent inhibitor of secreted phospholipase A(2), and cis,cis and trans,trans isomers, related with respect to the two proline amide bonds, are known. Crystals of cis,cis-CS were grown from N,N-dimethylacetamide solution, giving the title compound, the cyclic ester of isoleucyloxazolinylphenylalanylprolylthiazolylphenylalanylproline [cyclo(-Ile-Oxz-Phe-Pro-Thz-Phe-Pro-)] N,N-dimethylacetamide hemisolvate, C(41)H(49)N(7)O(6)S.0.5C(4)H(9)NO. The structure is the third example of cis,cis-CS to be investigated and comprises twinned crystals, in which the a and b axes are interchanged. The ratio of co-existing twin crystals is approximately 50%. The peptide has a 'saddle-like' structure and is very similar to previously reported structures of cis,cis-CS, which implies that the structure of cis,cis-CS is very stable in spite of differences in crystallization conditions.
authors.affiliation: Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. doit@gly.oups.ac.jp
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Doi
authors.forename: Akiko
authors.initials: A
authors.lastname: Asano
authors.forename: Kenji
authors.initials: K
authors.lastname: Yoza
mesh_terms: D004791:Enzyme Inhibitors / Q000737:chemistry; D008958:Models, Molecular; D010456:Peptides, Cyclic / Q000737:chemistry*; D010741:Phospholipases A / Q000037:antagonists & inhibitors
chemical_list: D004791:Enzyme Inhibitors; D010456:Peptides, Cyclic; C414083:ceratospongamide; D010741:Phospholipases A