Busam K, Decker K
Eur J Biochem. 1986 Oct 1;160(1):23-30. doi: 10.1111/j.1432-1033.1986.tb09934.x.
Three sialyltransferase activities involved in ganglioside biosynthesis were studied in Golgi-enriched preparations of rat liver: the formation of GM3, GD3 and GD1a. The conditions for the quantitative assays of these enzymatic reactions were standardized and optimized, with Triton X-100 being used as detergent. The apparent Km values of each sialyltransferase for N-acetyl-2-(5'-cytidylyl)neuraminic acid (1.5 mM with GM3 synthase, 0.2 mM with GD3 synthase, and 0.5 mM with GD1a synthase) and the respective glycolipid substrates (0.08 mM for lactosylceramide, 0.1 mM for GM3, and 0.5 mM for GM1) were determined. Competition experiments showed that the three sialyltransferase activities are three individual catalytic entities. Moreover, evidence was found that product inhibition may play a role in the regulation of the activity of sialyltransferases.
GM3、GD3和GD1a的形成。以Triton X-100作为去污剂，对这些酶促反应的定量测定条件进行了标准化和优化。测定了每种唾液酸转移酶对N-乙酰-2-(5'-胞苷基)神经氨酸（GM3合酶为1.5 mM，GD3合酶为0.2 mM，GD1a合酶为0.5 mM）和各自糖脂底物（乳糖基神经酰胺为0.08 mM，GM3为0.1 mM，GM1为0.5 mM）的表观Km值。竞争实验表明，这三种唾液酸转移酶活性是三个独立的催化实体。此外，发现有证据表明产物抑制可能在唾液酸转移酶活性的调节中起作用。
