THE STRUCTURE OF THE 2/1 CHANNEL INCLUSION COMPOUND BETWEEN DEOXYCHOLIC-ACID AND PINACOLONE, 2C24H40O4.C6H12O

The title compd., 4C24H40O4.C14H15N3, crystd. in space group P212121 with a 25.676(8), b 13.731(3), and c 7.160(2) .ANG.; d.(exptl.) = 1.17 and d.(calcd.) = 1.18 for Z = 4. The structure was refined to R = 0.093 and RW = 0.099 for 1810 obsd. reflections with I > 2.sigma.(I). At. parameters are given. The crystal packing is characterized by an assembly of pleated antiparallel bilayers, nearly equal to that of the acetophenone-choleic acid complex, which give rise to canals filled by p-dimethylaminoazobenzene mols. The guest mols., located by van der Waals energy calcns., run along c and have their long axes approx. parallel to c. The C(5), C(6), C(19), C(20), C(21), and C(22) atoms, together with their H atoms, are engaged in strong interactions with the atoms of p-dimethylaminoazobenzene

Conformations in solution of the fuscopeptins - Phytotoxic metabolites of Pseudomonas fuscovaginae

Fuscopeptins are phytotoxic amphiphilic lipodepsipeptides containing 19 amino acid residues. They are produced by the plant pathogenic bacterium Pseudomonas fuscovaginae in two forms, A and B, which differ only in the number of methylene groups in the fatty acid chain. Their covalent structure and biological properties have been reported previously. CD and NMR spectroscopy investigations in solution revealed the absence of identifiable elements of secondary and tertiary structure for these molecules. Fuscopeptin B appears to be completely unstructured in aqueous solution, and has a large molecular flexibility. A dramatic conformational change was observed upon addition of trifluoroethanol. This study reports the complete interpretation of the two-dimensional NMR spectra and the NOE results obtained for fuscopeptin B in water/trifluoroethanol solutions; the signals relative to the peptidic moiety are identical to those observed for fuscopeptin A. The results of this investigation were used to determine the solution structure of fuscopeptin B by computer simulations applying distance geometry and simulated annealing procedures. In water/trifluoroethanol solutions the peptidic region appears to have a partly helical structure. The lactonic ring assumes defined conformations very similar to these already reported for other lipodepsipeptides. The structure for fuscopeptin B in solution is also valid for fuscopeptin A because of the negligible structural difference between the two metabolites

Solution conformation of the Pseudomonas syringae MSU 16H phytotoxic lipodepsipeptide Pseudomycin A determined by computer simulations using distance geometry and molecular dynamics from NMR data

Pseudomycin A is a cyclic lipodepsinonapeptide phytotoxin produced by a strain of the plant pathogenic bacterium Pseudomonas syringae. Like other members of this family of bacterial metabolites, it is characterised by a fatty acylated cyclic peptide with mixed chirality and lactonic closure. Several biological activities of Pseudomycin A are lower than those found for some of its congeners, a difference which might depend on the diverse number and distribution of charged residues in the peptide moiety. Hence, it was of interest to investigate its conformation in solution. After the complete interpretation of the two-dimensional NMR spectra, NOE data were obtained and the structure was determined by computer simulations, applying distance geometry and molecular dynamics procedures. The conformation of the large ring of Pseudomycin A in solution includes three rigid structural regions interrupted by three short flexible regions that act as hinges. The overall three-dimensional structure of the cyclic moiety is similar to that of previously studied bioactive lipodepsinonapeptides produced by other pseudomonads

Conformations in solution of the fuscopeptins - Phytotoxic metabolites of Pseudomonas fuscovaginae

Fuscopeptins are phytotoxic amphiphilic lipodepsipeptides containing 19 amino acid residues. They are produced by the plant pathogenic bacterium Pseudomonas fuscovaginae in two forms, A and B, which differ only in the number of methylene groups in the fatty acid chain. Their covalent structure and biological properties have been reported previously. CD and NMR spectroscopy investigations in solution revealed the absence of identifiable elements of secondary and tertiary structure for these molecules. Fuscopeptin B appears to be completely unstructured in aqueous solution, and has a large molecular flexibility. A dramatic conformational change was observed upon addition of trifluoroethanol. This study reports the complete interpretation of the two-dimensional NMR spectra and the NOE results obtained for fuscopeptin B in water/trifluoroethanol solutions; the signals relative to the peptidic moiety are identical to those observed for fuscopeptin A. The results of this investigation were used to determine the solution structure of fuscopeptin B by computer simulations applying distance geometry and simulated annealing procedures. In water/trifluoroethanol solutions the peptidic region appears to have a partly helical structure. The lactonic ring assumes defined conformations very similar to these already reported for other lipodepsipeptides. The structure for fuscopeptin B in solution is also valid for fuscopeptin A because of the negligible structural difference between the two metabolites

Lipopeptide secondary metabolites from the phytopathogenic bacterium Pseudomonas syringae.

Over the past twenty years or so, significant advances have been made in the study of the secondary metabolism of the widespread phytopathogenic Gram-negative bacterium Pseudomonas syringae. Interdisciplinary approach, which required the expertise of plant pathologists, chemists, biochemists and molecular biologists, led to the discovery of a new family of bioactive peptide secondary metabolites. The determination of their structures was pivotal for the investigations on their biosynthetic pathways, their relevance in the development of plant disease, and for the understanding of the molecular bases of their biological activities in plant, microbial and animal cells. In particular, the antibiotic activities of some of these compounds appear very interesting in the perspective of their utilization both in medicine and in agriculture. The goal of this chapter is to summarize the present knowledge in various areas of research on P. syringae peptide metabolites