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JKMRS Volume 19, No 2, pp 67-73;Isolation of Microcystin-LR an...
2015년 10월 13일 / 조회수: 574

Isolation of Microcystin-LR and Its Potential Function of Ionophore

 

 

Gilhoon Kim, Seungwon Han, Hoshik Won*

 

 

Department of Applied Chemistry, Hanyang University, 55, Hanyang Daehak-Ro, Sangrok-Gu,

Ansan 426-791, Korea Republic of Korea

 

 

 

 

Received July 28, 2015; Revised Sep 18, 2015; Accepted Sep 27, 2015

 


Abstract The microcystin is a cyclic heptapeptide from metabolites of cyanobacteria in the genera mycrocystis, anabaeba as a result of eutrophication. It has been known that microcystin-LR is a potent inhibitor of the catalytic subunits of protein phosphatase-1 (PP-1) as well as powerful tumor promoter. The active site of microcystin actually has two metal ions Fe2+/Zn2+ close to the nucleophilic portion of PP-1-microcystin complex.

We report the isolation and purification of this microcystin-LR from cyanobacteria (blue-green algae) obtained from Daechung Dam in Chung-cheong Do, Korea. Microcystin-LR was extracted from solid-phase extraction (SPE) sample preparation using a CN cartridge. The cyanobacteria extract was purified to obtain microcystin-LR by HPLC method and identified by LC/MS.

The detail structural studies that can elucidate the possible role of monovalent and divalent metal ions in PP-1-microcystin complexation were carried out by utilizing molecular dynamics. Conformational changes in metal binding for ligands were monitored by molecular dynamic computation and potential of mean force (PMF) using the method of the free energy perturbation. The microcystin-metal binding PMF simulation results exhibit that microcystin can have very stable binding free energy of -10.95 kcal/mol by adopting the Mg2+ ion at broad geometrical distribution of  0.5~4.5Å, and show that the K+ ion can form a stable metal complex rather than other monovalent alkali metal ions.

 

Keywords Microcystin-LR, Molecular dynamics, Metal complex

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