BIOTECHNOLOGICAL STUDIES ON THE BIOSYNTHESIS OF DIMETHYLSULPHONIOPROPANOIC ACID IN DINOPHYCEAE AND CHILOROPHYCEAE

舞鹤湾海水中生物源二甲基硫（DMS）的浓度在一年内从0.04到18.0 mug DMS/l不等。虽然这些浓度的DMS与叶绿素a的浓度的发病率略有一致，一个很好的相关性之间的DMS和叶绿素a的浓度在甲藻的赤潮沃茨，如海洋原甲藻和长崎裸甲藻。粗略估计，夏季从沿海水域到大气的DMS平均通量为10^3 mg S/m^<2.>d，是冬季通量的100倍。在Seisui maru和Hakuho-maru的巡航期间，还确定了西亚热带太平洋表层海水和垂直水文剖面中的DMS。DMS在真光层中的垂直分布遵循初级生产力的垂直分布，最大值出现在洋面或靠近洋面处，随深度增加而减小。低于1%的光穿透水平，DMS水平逐渐下降。 ...更多信息 盟友日本近海以及热带和亚热带太平洋表层水的平均DMS浓度分别为611和265纳克DMS/升。二甲基硫是海洋中主要的挥发性硫化物，通过海-气界面的迁移对大气硫收支有重要的贡献，叔硫化合物二甲基硫代丙酸（DMTP，= dimethylpropiothetine）是二甲基硫的前体，甲硫氨酸是甲藻隐甲藻（Crypthecodiniumcohnii）合成DMTP的有效前体.结果表明，甲硫氨酸通过脱羧、脱氨、氧化和甲基化等反应生成DMTP。该酶的分子量约为240 KDa，由2个亚基组成。Km值为16.3 mM。该酶需要磷酸吡哆醛。该酶的N端氨基酸序列为Ala-Leu-X-Trp-Ser-Asp-Ile-Ser-Arg-。少

The concentration of biogenic dimethylsulphide(DMS) in the sea water in Maizuru Bay in one year ranged from 0.04 tO 18.0 mug DMS/l. Although these concentrations of DMS coincide slightly with the incidence of the concentration of chlorophyll a, a good correlation was obtained between concentration of DMS and chlorophyll a in red tide waters of dinoflagellates such as Prorocentrum micans and Gymnodinium nagasakiense. Rough estimates for the average flux of DMS from coastal water to the atmosphere during the summer are of the order of 10^3 mg S/m^<2.>d, a 100-fold increse over th winter flux. DMS in surface seawater and vertical hydrographic profiles were also determined in the western, subtropical Pacific Ocean during the cruises of the Seisui-maru and Hakuho-maru. The vertical distribution of DMS in the euphotic zone follows that of primary production, with a maximum at or near the ocean surfce and a decrease with depth. Below the level of 1% light penetration, DMS levels decline gradu … More ally. The mean DMS concentrations in the surface water of the sea off Japan and the tropical and subtropical Pacific Ocean were 611 and 265 ng DMS/l, respectively. Since DMS is the major volatile sulphur compound in the ocean, it is suggested that estimated DMS transfer across the sea-air interface contributes significantly to the atmospheric sulphur budget.The tertiary sulphonium compound dimethylthiopropanoic acid(DMTP, = dimethylpropiothetine) is a precursor of DMS.Methionine is an efficient precursor for the biosynthesis of DMTP in the dinoflagellate Crypthecodinium cohnii. The methyl group, C-3 and C-4 carbons, and sulphur atoms of methionine were incorporated into DMTP, whereas C-1 carbon of methionine was not incorporated into DMTP.The results indicate that methionine is converted to DMTP by decarboxylation, deamination, oxidation, and methylation.Methionine decarboxylase was completely purified from C.cohnii and characterized. The molecular weight of this enzyme is about 240 KDa, consit of 2 subunits. Km value is 16.3 mM.The enzyme requires pyridoxalphosphate. The N-terminal amino acid sequence of the enzyme is Ala-Leu-X-Trp-Ser-Asp-lle-Ser-Arg-----. Less