Crystallographic structure of a multiple beta-turn containing, glycine-rich heptapeptide: a synthetic precursor of the lipopeptaibol antibiotic trichodecenin I.
In continuation of our studies on the structure and function of peptaibol antibiotics, the conformational properties of a sequence analogous to that of Trichodecenin I (Z-Gly-Gly-D-Leu-Aib-Gly-D-Ile-D-Leu-OMe, where Z = benzyloxycarbonyl, Aib = alpha-aminoisobutyric acid, and OMe = methyl ester) have been investigated crystallographically. This sequence is the mirror image of the naturally occurring molecule and also of the C-terminal heptapeptide of the related lipopeptaibol Trichogin A IV (where, however, the Leu-OMe residue has replaced the original Leuol residue). The molecule crystallized in the monoclinic system, space group P21, Z = 4, and cell parameters a = 11.610(5), b = 33.342(8), c = 11.735(4) A, beta = 110.42(1) degrees, V = 4257(3) A3. The crystallographic refinement converges at residual values of R = 0.047 and wR2 = 0.134 on F2. In the 1-5 segment the molecular conformation is virtually identical to that one reported from solution nmr studies of a similarly protected sequence [Biopolymers (1995), Vol. 35. pp. 21-29)] and is characterized by beta-turns of type I at Gly1-Gly2, II' at Leu3-Aib4, and I at Aib4-Gly5. In the crystal structure, a beta-sheet-like arrangement is seen at the C-terminus.
Monaco
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Department of Organic Chemistry, University of Padova, Italy.
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Crisma
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Toniolo
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Shui
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Eggleston
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DS
D000900:Anti-Bacterial Agents / Q000737:chemistry; D000890:Anti-Infective Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005231:Fatty Acids, Unsaturated / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D055666:Lipopeptides; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides; D011487:Protein Conformation; D017433:Protein Structure, Secondary
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D005231:Fatty Acids, Unsaturated; D055666:Lipopeptides; D009842:Oligopeptides; D010455:Peptides; C087937:trichogin A IV; C087388:trichodecenin I