Conformational studies of microcystin-LR using NMR spectroscopy and molecular dynamics calculations

Gull-Britt Trogen, Arto Annila, John Eriksson, Maarit Kontteli, Jussi Meriluoto, Ingmar Sethson, Janusz Zdunek, Ulf Edlund (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

50 Citations (Scopus)


NMR spectroscopy in aqueous and dimethyl sulfoxide/water solutions is used to determine the three-dimensional structures of microcystin-LR, a cyclic cyanobacterial heptapeptide toxin which is a potent inhibitor of type 1 and type 2A protein phosphatases. The conformations of this toxic peptide are studied using a simulated annealing (SA) protocol followed by refined SA calculations in vacuo and free MD simulations in water. Only one conformational family in each solvent is found. The peptide ring has a saddle-shaped form, essentially the same in both solvents. The structural difference observed between the two solution structures is located to the part consisting of Mdha, Ala, and Leu. This peptide segment is not present in nodularin, a cyclic pentapeptide of similar toxicity. The Arg side chain is very flexible, while the side chain of Leu is well defined. The side chain of Adda, essential for toxicity, is constrained in the vicinity of the backbone ring but appears to be flexible in the more remote part.
Original languageEnglish
Pages (from-to)3197-3205
Issue number10
Publication statusPublished - 1996
MoE publication typeA1 Journal article-refereed


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