title: Unguisin C, a GABA-containing cyclic peptide from the fungus Emericella unguis.
abstract: Besides the known unguisins A and B, a new cyclic heptapeptide, unguisin C, containing a GABA-derived moiety in the ring, was isolated from the fungus Emericella unguis. The structure was determined by 1D and 2D NMR techniques. Marfey's method was used to determine the absolute stereochemistry. Precursor-directed biosynthesis of the unguisins was performed by supplementation of the culture medium with amino acids (L-Ala, L-Ser, L-Phe and L-Leu). A related cyclic heptapeptide, unguisin D, was detected by HPLC and characterized by sequence analysis using LC-QITMS.
authors.affiliation: Department of Structural Chemistry, Pharmaceuticals Development, Research and Development, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Maaloev, Denmark. joms@novonordisk.com
authors.forename: Joan
authors.initials: J
authors.lastname: Malmstrøm
authors.forename: Anne
authors.initials: A
authors.lastname: Ryager
authors.forename: Uffe
authors.initials: U
authors.lastname: Anthoni
authors.forename: Per Halfdan
authors.initials: PH
authors.lastname: Nielsen
mesh_terms: D032842:Emericella / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification*; D011487:Protein Conformation; D013057:Spectrum Analysis; D005680:gamma-Aminobutyric Acid / Q000737:chemistry*
chemical_list: D010456:Peptides, Cyclic; C470777:unguisin C; D005680:gamma-Aminobutyric Acid