Tsai P K, Gracy R W
J Biol Chem. 1976 Jan 25;251(2):364-7.
Methylglyoxal synthetase, which catalyzes the conversion of dihydroxyacetone phosphate to methylglyoxal and inorganic phosphate, has been isolated and crystalized in good yields from Proteus vulgaris. The enzyme was shown to be homogeneous by a variety of criteria and was found to be a dimer (Mr = 135,000; s20,w = 7.2 S) composed of two apparently identical catalytic and physical properties and their interconvertible nature suggest that they do not represent true isozymes. The enzyme is specific for dihydroxyacetone phosphate and does not form methylglyoxal from glyceraldehyde 3-phophate, glyceraldehyde, or dihydroxyacetone. Nonphosphorylated analogs are neither substrates nor competive inhibitors, but a variety of phosphorylated analogs are competitive with respect to dihydroxyacetone phosphate. The enzyme is inhibited by inorganic orthophosphate in a complex manner which is overcome by dihydroxyacetone phosphate in a signoidal manner
甲基乙二醛合成酶催化磷酸二羟丙酮转化为甲基乙二醛和无机磷酸，已从普通变形杆菌中分离出来并以高产率结晶。通过多种标准表明该酶是纯一的，发现它是一种二聚体（Mr = 135,000；s20,w = 7.2 S），由两个明显相同的亚基组成，其催化和物理性质以及它们的相互转化性质表明它们不代表真正的同工酶。该酶对磷酸二羟丙酮具有特异性，不能由3-磷酸甘油醛、甘油醛或二羟丙酮形成甲基乙二醛。非磷酸化类似物既不是底物也不是竞争性抑制剂，但多种磷酸化类似物相对于磷酸二羟丙酮具有竞争性。该酶以复杂的方式被无机正磷酸盐抑制，而磷酸二羟丙酮以S形方式克服这种抑制。
