title: Structure determination of neoefrapeptins A to N: peptides with insecticidal activity produced by the fungus Geotrichum candidum.
abstract: The structures of neoefrapeptins A to N, peptides with insecticidal activity, were elucidated. They showed a close similarity to efrapeptin. However, all neoefrapeptins contained the very rare amino acid 1-amino-cyclopropane-carboxylic acid and some of them also contained (2S,3S)-3-methylproline. The neoefrapeptins are the first case, in which these amino acids are found as building blocks for linear peptides. They were identified by comparison of the silylated hydrolyzate to reference material by GC/MS (EI-mode). The sequence was elucidated using mass spectrometry (ESI+ mode). Full scan spectra showed two fragments in high yield, even under mild ionization conditions. MS/MS spectra of these two fragments yielded fragment rich spectra from which the sequence of the compounds was determined almost completely. The proteolytic cleavage with the proteinase papain yielded products that allowed to prove the rest of the sequence and the identity of the C-terminus to efrapeptin. The proteolytic cleavage products allowed furthermore to determine the position of the isobaric amino acids, pipecolic acid and 3-methylproline in neoefrapeptin F, as well as the location of R-isovaline and S-isovaline. Papain digestion was such established as a tool for structure elucidation of peptides rich in alpha,alpha-dialkylated amino acids. CD spectra suggested a 3(10) helical structure for neoefrapeptins A and F.
authors.affiliation: Syngenta Crop Protection, Research, CPR Analytics, 4002 Basel, Switzerland. andreas.fredenhagen@novartis.com
authors.forename: Andreas
authors.initials: A
authors.lastname: Fredenhagen
authors.forename: Louis-Pierre
authors.initials: LP
authors.lastname: Molleyres
authors.forename: Bettina
authors.initials: B
authors.lastname: Böhlendorf
authors.forename: Grit
authors.initials: G
authors.lastname: Laue
mesh_terms: D000522:Alphaprodine / Q000031:analogs & derivatives / Q000032:analysis; D000595:Amino Acid Sequence; D000598:Amino Acids, Cyclic / Q000032:analysis; D002942:Circular Dichroism; D005656:Fungal Proteins / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D005848:Geotrichum / Q000737:chemistry*; D007306:Insecticides / Q000737:chemistry*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010206:Papain / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D010875:Pipecolic Acids / Q000032:analysis; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000598:Amino Acids, Cyclic; D005656:Fungal Proteins; D007306:Insecticides; D010455:Peptides; D010875:Pipecolic Acids; D000522:Alphaprodine; C023863:1-aminocyclopropane-1-carboxylic acid; C012953:efrapeptin; C047292:1,3,3-trimethyl-4-phenyl-4-(propionyloxy)piperidine; D010206:Papain; C031345:pipecolic acid