title: Fractionation Protocol for the Isolation of Polypeptides from Plant Biomass
abstract: A fractionation protocol for the isolation of a highly purified polypeptide fraction from plant biomass is described. The procedure dereplicates ubiquitous substance classes known to interfere with bioassays often used in natural product-based drug discovery programs. The protocol involves pre-extraction with dichloromethane, extraction with ethanol (50%), removal of tannins with polyamide, removal of low-molecular-weight components with size-exclusion chromatography over Sephadex G-10, and final removal of salts and polysaccharides with solid-phase extraction using reversed-phase cartridges. The method has been applied to the aerial parts of Viola arvensis, resulting in the isolation of a peptide fraction that on further separation yielded a novel 29-residue macrocyclic polypeptide named varv peptide A, cyclo(-TCVGGTCNTPGCSCSWPVCTRNGLPVCGE-).
authors.affiliation: Division of Pharmacognosy, Department of Pharmacy, Biomedical Center, Uppsala University, Box 579, S-751 23 Uppsala, Sweden.
authors.initials: P
authors.lastname: Claeson
authors.initials: U
authors.lastname: Göransson
authors.initials: S
authors.lastname: Johansson
authors.initials: T
authors.lastname: Luijendijk
authors.initials: L
authors.lastname: Bohlin