title: Synthesis of an N-methyldehydroalanine-containing fragment of microcystin by combination of solid phase peptide synthesis and beta-elimination in solution.
abstract: A new method for the synthesis of dehydroalanine (delta Ala)-containing peptides has been developed by combining solid phase peptide synthesis (tert-butyloxycarbonyl/HF-chemistry) with solution synthesis. A sequence from cyanobacterial hepatotoxin microcystin, Ac-D-gamma-Glu-[N-Me-delta Ala]-D-Ala-Leu amide was chosen as a model peptide. The precursor for the synthesis of the dehydroalanine-containing peptide, Ac-D-gamma-Glu-[N,S-diMeCys]-D-Ala-Leu, was synthesized on a solid phase followed by sulfonium salt formation on the resin. The resulting S,S-dimethylated peptide was cleaved from the resin with liquid HF. The HPLC-purified S,S-dimethylated cysteine-containing precursor peptide was subjected to beta-elimination in solution catalysed by DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) in methanol. The final product, Ac-D-gamma-Glu-[N-Me-delta Ala]-D-Ala-Leu amide, was purified by HPLC, and analysed by mass spectrometry and 1H NMR spectroscopy. The stability of the model peptide under acidic, neutral and basic conditions has been studied.
authors.affiliation: Department of Neurochemistry and Neurotoxicology, Arrhenius Laboratories, Stockholm University, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Zetterström
authors.forename: L
authors.initials: L
authors.lastname: Trogen
authors.forename: L G
authors.initials: LG
authors.lastname: Hammarström
authors.forename: L
authors.initials: L
authors.lastname: Juhlin
authors.forename: B
authors.initials: B
authors.lastname: Nilsson
authors.forename: C
authors.initials: C
authors.lastname: Damberg
authors.forename: T
authors.initials: T
authors.lastname: Bartfai
authors.forename: U
authors.initials: U
authors.lastname: Langel
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D052998:Microcystins; D008969:Molecular Sequence Data; D015394:Molecular Structure; D008970:Molecular Weight; D010446:Peptide Fragments / Q000138:chemical synthesis* / Q000302:isolation & purification; D010456:Peptides, Cyclic / Q000737:chemistry*
chemical_list: D052998:Microcystins; D010446:Peptide Fragments; D010456:Peptides, Cyclic; C078588:microcystin; C037064:N-methyldehydroalanine; D000409:Alanine