Bushway A A, Keenan T W
Biochim Biophys Acta. 1979 Jan 29;572(1):146-52. doi: 10.1016/0005-2760(79)90209-1.
Bovine milk was found to contain, in soluble form, an enzyme which transfers galactose from UDPgalactose to glucosylceramide. This enzyme was partially purified by the same procedure used to isolate the galactosyltransferase of lactose synthetase. The partially purified enzyme required detergents for activity, had a pH optimum of 7.2--7.3 and required Mn2+. The apparent Km calculated for glucosylceramide was 1.33 . 10(-4) M. With glucosylceramide as acceptor the product of the reaction was identified as lactosylceramide by autoradiography on thin-layer chromatograms. Lactosylceramide was also an effective acceptor for the transferase reaction but neutral glycosphingolipids or gangliosides with terminal galactose of N-acetylgalactosamine residues were ineffective or poorly effective as acceptors. Addition of alpha-lactalbumin inhibited the transferase reaction.
人们发现牛乳中含有一种以可溶形式存在的酶,该酶可将半乳糖从尿苷二磷酸半乳糖转移至葡萄糖神经酰胺。通过用于分离乳糖合成酶的半乳糖基转移酶的相同程序,对该酶进行了部分纯化。部分纯化的酶的活性需要去污剂,最适pH为7.2 - 7.3,且需要锰离子。计算得出葡萄糖神经酰胺的表观Km为1.33×10⁻⁴ M。以葡萄糖神经酰胺作为受体时,通过薄层色谱放射自显影法将反应产物鉴定为乳糖神经酰胺。乳糖神经酰胺也是转移酶反应的有效受体,但具有N - 乙酰半乳糖胺残基末端半乳糖的中性糖鞘脂或神经节苷脂作为受体无效或效果不佳。添加α - 乳白蛋白可抑制转移酶反应。