Fitzgerald J W
Biochem J. 1973 Oct;136(2):361-9. doi: 10.1042/bj1360361.
Pseudomonas C(12)B and other Pseudomonas species released larger amounts of a (35)S-labelled metabolite into the medium when cultured on growth-limiting concentrations of Na(2)SO(4) as opposed to growth in SO(4) (2-)-sufficient media. The metabolite was found at all stages of the culture cycle of Pseudomonas C(12)B and maximum quantities occurred in stationary-phase culture supernatants. The metabolite was not detected when the bacterium was cultured on growth-limiting concentrations of potassium phosphate. The amount of the metabolite present in the medium greatly exceeded that which could be extracted from intact cells and, except for choline chloride, it was independent of the carbon source used for growth. If choline chloride was present in high concentration, then larger amounts of the metabolite were found in the culture medium. The metabolite was not detected extracellularly or intracellularly when the bacterium was grown in SO(4) (2-)-deficient media containing 5mm-l-cysteine. The same metabolite was also synthesized in vitro only when Pseudomonas C(12)B extracts were incubated with choline chloride, ATP, MgCl(2) and Na(2) (35)SO(4). The metabolite-forming system was not subject to repression by Na(2)SO(4) and was completely inhibited by 0.5mm-l-cysteine and activated by Na(2)SO(4) (up to 1.0mm). The metabolite was identified as choline O-sulphate by electrophoresis, chromatography and isotope-dilution analysis. Another (35)S-labelled metabolite was also detected in culture supernatants, but was not identified.
当在生长受限浓度的硫酸钠中培养时，假单胞菌C(12)B和其他假单胞菌属物种向培养基中释放了大量的(35)S标记代谢物，而在硫酸根离子充足的培养基中生长时则不然。在假单胞菌C(12)B的培养周期的所有阶段都发现了这种代谢物，并且在稳定期培养上清液中出现了最大量。当细菌在生长受限浓度的磷酸钾中培养时，未检测到这种代谢物。培养基中存在的代谢物量大大超过了从完整细胞中可提取的量，并且除了氯化胆碱外，它与用于生长的碳源无关。如果氯化胆碱以高浓度存在，则在培养基中发现了更多量的代谢物。当细菌在含有5mM - l-半胱氨酸的硫酸根离子缺乏的培养基中生长时，在细胞外或细胞内均未检测到这种代谢物。仅当假单胞菌C(12)B提取物与氯化胆碱、ATP、MgCl₂和Na₂(35)SO₄一起孵育时，才在体外合成了相同的代谢物。形成代谢物的系统不受硫酸钠的抑制，并且被0.5mM - l-半胱氨酸完全抑制，并被硫酸钠（高达1.0mM）激活。通过电泳、色谱和同位素稀释分析将该代谢物鉴定为胆碱O-硫酸盐。在培养上清液中还检测到了另一种(35)S标记的代谢物，但未鉴定出来。
