title: Purification and characterization of paralytic shellfish toxin-transforming enzyme, sulfocarbamoylase I, from the Japanese bivalve Peronidia venulosa.
abstract: The Japanese bivalve Peronidia venulosa contains paralytic shellfish toxin (PST)-transforming enzymes that convert the weakly toxic C-toxins to the more potent decarbamoyl toxins. The enzyme was purified 154-fold with a yield of 0.26% and was named sulfocarbamoylase I. It was found to be a protein with an estimated molecular weight of 300 kDa by gel filtration column chromatography. Observation of a single band equivalent to 150 kDa on SDS-PAGE with or without reducing agents suggested it to be a homodimer with ionically bound subunits. The enzyme catalyzes the hydrolysis of the carboxyl bond in the N-sulfocarbamoyl moiety of PSP-toxins. The sulfonyl moiety in the carbamoyl side chain of substrates is essential for enzyme recognition. The N-terminal amino acid sequences of nine tryptic peptides were determined by the Edman degradation method. In a database search using the BLAST program, no protein that shows remarkable homology was retrieved. Several characteristics of the enzyme were also compared with those of another PST-transforming enzyme, carbamoylase I, which was previously isolated from the Japanese clam Mactra chinensis.
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori - Amamiyamachi, Sendai 981-8555, Japan. choyuko@biochem.tohoku.ac.jp
authors.forename: Yuko
authors.initials: Y
authors.lastname: Cho
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Ogawa
authors.forename: Miyako
authors.initials: M
authors.lastname: Takahashi
authors.forename: Hsi-Pin
authors.initials: HP
authors.lastname: Lin
authors.forename: Yasukatsu
authors.initials: Y
authors.lastname: Oshima
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D049872:Bivalvia / Q000201:enzymology* / Q000235:genetics; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D007564:Japan; D008387:Marine Toxins / Q000378:metabolism* / Q000633:toxicity; D008954:Models, Biological; D008970:Molecular Weight; D010446:Peptide Fragments / Q000235:genetics / Q000302:isolation & purification; D013379:Substrate Specificity; D014018:Tissue Distribution
chemical_list: D008387:Marine Toxins; D010446:Peptide Fragments; D002265:Carboxylic Ester Hydrolases; C092629:paralytic shellfish poisoning toxin carbamoylase