| Autor: |
Sako, Yoshihiko, Yoshida, Takashi, Uchida, Aritsune, Arakawa, Osamu, Noguchi, Tamao, Ishida, Yuzaburo |
| Předmět: |
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| Zdroj: |
Journal of Phycology; Dec2001, Vol. 37 Issue 6, p1044-1051, 8p, 2 Diagrams, 3 Charts, 4 Graphs |
| Abstrakt: |
A sulfotransferase (ST) specific to N-21 of saxitoxin (STX) and gonyautoxin 2+3 (GTX2+3) designated as N-ST was purified to homogeneity from the cytosolic fraction of clonal-axenic vegetative cells of the toxic dinoflagellate Gymnodinium catenatum Graham GC21V, which causes paralytic shellfish poisoning. The enzyme transferred a sulfate group from 3′-phosphoadenosine 5′-phosphosulfate (PAPS) to N-21 in the carbamoyl group of STX and GTX2+3 to produce GTX5 and C1+2, respectively. The molecular mass of the purified enzyme was determined by SDS-PAGE to be 59 kDa. Gel filtration chromatography showed a native molecular mass of 65 kDa, indicating that the N-ST is a monomeric enzyme. The N-ST was specific to only N-21 of STX and GTX2+3, and O-22 sulfation was not observed. Moreover, the N-ST was not active toward neo STX and GTX1+4, which differed from STX and GTX2+3, respectively, in only N-1 hydroxylation. When various compounds previously reported to be substrates for STs in other organisms and paralytic shellfish poisoning toxins other than STX and GTX2+3 were added to the reaction mixture, N-ST activity was not decreased. The enzyme required PAPS as the sole source of sulfate. The enzyme was optimally active at pH 6.0 and 25° C, and its activity was enhanced by Mg2+ and Co2+. The Km values of the N-ST for STX and GTX2+3 were 16.1 μM and 29.8 μM, respectively. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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