Further investigation of microbial degradation of microcystin using the advanced Marfey method.
It is known that microcystin (MC) is subject to microbial degradation to provide three types of products, linearized MCLR (Adda-Glu-Mdha-Ala-Leu-MeAsp-Arg), tetrapeptide Adda-Glu-Mdha-Ala, and Adda. They can be readily detected by the usual HPLC, because they commonly have an Adda moiety with a diene and an absorption maximum at 238 nm as the chromophore. However, no other degradation products without such a chromophore have been isolated to date. In this study, cell preparation of a bacterium B-9 that can degrade MC and detection of the degradation products were devised. First, we regulated the B-9 hydrolytic activity by washing with sodium chloride solution to obtain a desired cell preparation, which permitted an additional intermediate and the final products of MCLR to be obtained. Second, the resulting products could be firmly identified using the advanced Marfey method with the aid of log D. As a result of these experiments, the following degradation products were further identified: a tetrapeptide, Adda-Glu-Mdha-Ala, tripeptides Adda-Glu-Mdha, Glu-Mdha-Ala, and Arg-MeAsp-Leu, a dipeptide, Glu-Mdha, and amino acids Adda, Arg, and methylamine derived from Mdha. The present study expands the hydrolytic activity of the B-9 strain, which can hydrolyze not only cyanobacterial cyclic peptides but also MC to the intermediates and final products. The established characterization method composed of the advanced Marfey method and log D would be a standard technique for the structural characterization of a mixture of amino acids and peptides.
Hashimoto
Elisabete Hiromi
EH
Graduate School of Environmental and Human Science and Faculty of Pharmacy, Meijo University, Tempaku, Nagoya 468-8503, Japan.
Kato
Hajime
H
Kawasaki
Yoshito
Y
Nozawa
Yuriko
Y
Tsuji
Kiyomi
K
Hirooka
Elisa Yoko
EY
Harada
Ken-ichi
K
D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000378:metabolism; D052998:Microcystins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization
D052998:Microcystins; C078588:microcystin