Liquid chromatography-mass spectrometry identification of microcystins inMicrocystis aeruginosa strain from lake Thanh Cong, Hanoi, Vietnam

Hummert, Ch.; Dahlmann, J.; Reinhardt, Klaus; Dang, H. Ph. H.; Dang, Dinh Kim; Luckas, Bernd

doi:10.1007/bf02492180

Cited by 52 publications

(27 citation statements)

References 32 publications

(14 reference statements)

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“…It is likely that some of these oxidized tryptophan microcystin congeners have been encountered in the past, as mass-to-charge ratios consistent with MC-OiaR and/or MC-NfkR have been reported previously [32,33]. In both of these studies, MC-WR was present in the samples, making it likely that oxidized tryptophan microcystins would also have been present.…”

Section: Resultssupporting

confidence: 75%

Structural Characterization of New Microcystins Containing Tryptophan and Oxidized Tryptophan Residues

et al. 2013

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Microcystins are cyclic peptides produced by cyanobacteria, which can be harmful to humans and animals when ingested. Eight of the (more than) 90 microcystin variants presently characterized, contain the amino acid tryptophan. The well-researched oxidation products of tryptophan; kynurenine, oxindolylalanine, and N-formylkynurenine, have been previously identified in intact polypeptides but microcystin congeners containing oxidized tryptophan moieties have not been reported. Liquid chromatography-tandem mass spectrometric analysis of an extract of Microcystis CAWBG11 led to the tentative identification of two new tryptophan-containing microcystins (MC‑WAba and MC-WL), as well as eight other microcystin analogs containing kynurenine, oxindolylalanine and N‑formylkynurenine (Nfk). Investigation of one of these congeners (MC‑NfkA) by nuclear magnetic resonance spectroscopy was used to verify the presence of Nfk in the microcystin. Liquid chromatography-mass spectrometry analysis of a tryptophan oxidation experiment demonstrated that tryptophan-containing microcystins could be converted into oxidized tryptophan analogs and that low levels of oxidized tryptophan congeners were present intracellularly in CAWBG11. MC-NfkR and MC-LNfk were detected in standards of MC-WR and MC-LW, indicating that care during storage of tryptophan-containing microcystins is required.

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Section: Resultssupporting

confidence: 75%

Structural Characterization of New Microcystins Containing Tryptophan and Oxidized Tryptophan Residues

et al. 2013

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“…The detection of MC-WR and MC-AR as a significant proportion of the microcystin pool is also unusual, and most likely reflects a unique strain. It is interesting that MC-WR was the predominant microcystin, along with MC-RR and MC-YR in a strain of Microcystis aeruginosa, isolated from Lake Thanh Cong in Vietnam (Hummert et al, 2001). No MC-LR was detected on this occasion.…”

Section: Discussionmentioning

confidence: 96%

Stability of toxigenic Microcystis blooms

2009

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“…The MC-LR molecule can be separated into several characteristic fragment ions whose m/z are 135,213,285,375,552,570 and 599 (Table 1). The fragment [phenyl-methylenemethyne-methoxy] (m/z = 135) is one of the most characteristic parts of MC-LR in Adda group (Hummert et al, 2001). The other fragments are shown in Table 1 (Mayumi et al, 2006).…”

Section: The Relationship Of Microcystin Biosynthesis and Ureamentioning

confidence: 98%