Seven new microcystins possessing two L-glutamic acid units, isolated from Anabaena sp. strain 186.
Electrospray ionization mass spectrometry has been applied to the structure assignment of seven new microcystins (1-7), obtained from cultured Anabaena sp. strain 186. The seven new microcystins contain the dehydroalanine (Dha) or L-Ser unit instead of the N-methyldehydroalanine unit and the L-Glu and/or its delta-methyl ester [E(OMe)] units at the two variable L-amino acid units, and the structures were assigned as [Dha7]microcystin-E(OMe)E(OMe) (1), [D-Asp3,Dha7]microcystin-E(OMe)E(OMe) (2), [L-Ser7]microcystin-E(OMe)E(OMe) (3), [D-Asp3,L-Ser7]microcystin-E(OMe)E(OMe) (4), [Dha7]microcystin-EE(OMe) (5), [D-Asp3,Dha7]microcystin-EE(OMe) (6), and [L-Ser7]microcystin-EE(OMe) (7). These microcystins are the first examples containing dicarboxylic amino acids at the two variable L-amino acid units in microcystins.
Namikoshi
M
M
Department of Ocean Sciences, Tokyo University of Fisheries, Japan. namikosh@tokyo-u-fish.ac.jp
Yuan
M
M
Sivonen
K
K
Carmichael
W W
WW
Rinehart
K L
KL
Rouhiainen
L
L
Sun
F
F
Brittain
S
S
Otsuki
A
A
D017033:Anabaena / Q000737:chemistry*; D001427:Bacterial Toxins / Q000032:analysis / Q000302:isolation & purification*; D018698:Glutamic Acid / Q000032:analysis / Q000737:chemistry*; D013058:Mass Spectrometry; D010456:Peptides, Cyclic / Q000032:analysis / Q000302:isolation & purification*
D001427:Bacterial Toxins; D010456:Peptides, Cyclic; D018698:Glutamic Acid