Cyclic Hexapeptide Dimers, Antatollamides A and B, from the Ascidian Didemnum molle. A Tryptophan-Derived Auxiliary for l- and d-Amino Acid Assignments.
Mariam N SalibTadeusz F MolinskiPublished in: The Journal of organic chemistry (2017)
Two dimerized cyclic hexapeptides, antatollamides A (1) and B (2), were isolated from the colonial ascidian Didemnum molle collected in Pohnpei. The amino acid compositions and sequences were determined by interpretation of MS and 1D and 2D NMR data. Raney Ni reduction of antatollamide A cleaved the dimer to the corresponding monomeric cyclic hexapeptide with replacement of Cys by Ala. The amino acid configuration of 1 was established, after total hydrolysis, by derivatization with a new chiral reagent, (5-fluoro-2,4-dinitrophenyl)-Nα-l-tryptophanamide (FDTA), prepared from l-Trp, followed by LCMS analysis; all amino acids were found to be l-configured except for d-Ala.
Keyphrases
- amino acid
- ms ms
- magnetic resonance
- mass spectrometry
- multiple sclerosis
- high resolution
- liquid chromatography tandem mass spectrometry
- simultaneous determination
- machine learning
- high performance liquid chromatography
- liquid chromatography
- tandem mass spectrometry
- big data
- computed tomography
- gas chromatography mass spectrometry
- capillary electrophoresis
- solid state
- anaerobic digestion
- metal organic framework