Structural characterization of toxic cyclic peptides from blue-green algae by tandem mass spectrometry.
Combined use of chemical degradation, derivatization, and tandem mass spectrometry for rapid structural characterization of toxic cyclic peptides from blue-green algae at the nanomole level is described. Previously, all blue-green algal toxins were thought to belong to a family of seven-residue cyclic peptides, having the general structure cyclo-D-Ala-L-Xaa-erythro-beta-methyl-D-isoaspartic acid-L-Yaa-Adda-D-isoglutamic acid-N-methyldehydroalanine, where Xaa and Yaa represent variable amino acids of the L configuration and Adda is 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid. Structural characterization of two additional toxins indicates that further variability can exist within this family of naturally occurring toxic cyclic peptides. Isoaspartic acid and dehydroalanine can substitute for beta-methylisoaspartic acid and N-methyldehydroalanine, respectively.
Krishnamurthy
T
T
U.S. Army Chemical Research, Development, and Engineering Center, Aberdeen Proving Ground, MD 21010-5423.
Szafraniec
L
L
Hunt
D F
DF
Shabanowitz
J
J
Yates
J R
JR
Hauer
C R
CR
Carmichael
W W
WW
Skulberg
O
O
Codd
G A
GA
Missler
S
S
D000595:Amino Acid Sequence; D000458:Cyanobacteria; D007202:Indicators and Reagents; D008387:Marine Toxins; D013058:Mass Spectrometry; D052998:Microcystins; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000302:isolation & purification; D010947:Plants, Toxic
D007202:Indicators and Reagents; D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C058503:toxin III, cyanobacterium; C058502:toxin II, cyanobacterium; C057862:cyanoginosin LR