Crow V L, Thomas T D
J Bacteriol. 1982 Aug;151(2):600-8. doi: 10.1128/jb.151.2.600-608.1982.
Two D-ketohexose 1,6-diphosphate aldolases are present in Streptococcus cremoris E8 and S. lactis C10. One aldolase, which was induced by growth on either lactose or galactose, was active with both tagatose 1,6-diphosphate (TDP) and fructose 1,6-diphosphate (FDP), having a lower Km and a higher Vmax with TDP as the substrate. This enzyme, named TDP aldolase, had properties typical of a class I aldolase, being insensitive to EDTA and showing substrate-dependent inactivation by sodium borohydride. Sodium dodecyl sulfate-gel electrophoresis indicated a subunit molecular weight of 34,500. The amino acid composition of TDP aldolase is reported. When the enzyme was incubated with either triose phosphates or FDP, the equilibrium mixture contained an FDP/TDP ratio of 6.9:1. The other aldolase, which had properties typical of a class II aldolase, showed activity with FDP but not with TDP. The intracellular TDP concentration, measured with the purified TDP aldolase, was 0.4 to 4.0 mM in cells growing on lactose or galactose and was lower (0 to 1.0 mM) in cells growing on glucose. The intracellular concentration of FDP was always higher than that of TDP. The role of ketohexose diphosphates in the regulation of end product fermentation by lactic streptococci is discussed.
嗜热链球菌E8和乳酸链球菌C10中存在两种D-酮己糖1,6-二磷酸醛缩酶。一种醛缩酶在乳糖或半乳糖上生长时被诱导，对塔格糖1,6-二磷酸（TDP）和果糖1,6-二磷酸（FDP）均有活性，以TDP为底物时具有较低的Km和较高的Vmax。这种酶被命名为TDP醛缩酶，具有I类醛缩酶的典型特性，对EDTA不敏感，且被硼氢化钠以底物依赖性方式灭活。十二烷基硫酸钠-凝胶电泳显示其亚基分子量为34,500。报道了TDP醛缩酶的氨基酸组成。当该酶与磷酸丙糖或FDP一起孵育时，平衡混合物中FDP/TDP的比例为6.9:1。另一种醛缩酶具有II类醛缩酶的典型特性，对FDP有活性，但对TDP无活性。用纯化的TDP醛缩酶测量，在以乳糖或半乳糖生长的细胞中，细胞内TDP浓度为0.4至4.0 mM，而在以葡萄糖生长的细胞中较低（0至1.0 mM）。细胞内FDP的浓度总是高于TDP。讨论了酮己糖二磷酸在乳酸链球菌终产物发酵调控中的作用。
