title: Isolation of two toxic heptapeptide microcystins from an axenic strain of Microcystis aeruginosa, K-139.
abstract: Two toxic heptapeptides were isolated from an axenic Microcystis aeruginosa strain, K-139. Using mainly a non-destructive NMR method, we determined the structure of the major toxin to be 7-desmethylmicrocystin LR which lacks an N-methyl group of the dehydroalanine moiety of microcystin LR. The minor toxin was deduced to be 3,7-didesmethylmicrocystin LR. The chromatographic and NMR analyses of 7-desmethylmicrocystin LR were compared with those of 3-desmethylmicrocystin LR.
authors.affiliation: Faculty of Pharmacy, Meijo University, Nagoya, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Harada
authors.forename: K
authors.initials: K
authors.lastname: Ogawa
authors.forename: K
authors.initials: K
authors.lastname: Matsuura
authors.forename: H
authors.initials: H
authors.lastname: Nagai
authors.forename: H
authors.initials: H
authors.lastname: Murata
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: Y
authors.initials: Y
authors.lastname: Itezono
authors.forename: N
authors.initials: N
authors.lastname: Nakayama
authors.forename: M
authors.initials: M
authors.lastname: Shirai
authors.forename: M
authors.initials: M
authors.lastname: Nakano
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001427:Bacterial Toxins / Q000737:chemistry / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D005856:Germ-Free Life; D046931:Microcystis / Q000032:analysis*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D001427:Bacterial Toxins; D010456:Peptides, Cyclic; C070123:3,7-didesmethylmicrocystin LR; C070122:7-desmethylmicrocystin LR