To develop transglycosylation for efficient preparation of N-acetyllactosamine (Galβ(1[Formula: see text]4)GlcNAc, LacNAc), β-galactosidase mediated transglycosylation using novel substrates Bacillus Circulans was explored. To make transglycosylation entropically favorable over hydrolysis, donor (lactose or galactose) and acceptor (N-acetyl glucosamine, GlcNAc) components were connected to a single molecule. For that purpose, 1,2- and 1,3-benzene dimethanol and 2-hydroxy-5-nitro- and 5-hydroxy-2-nitro-benzyl alcohol were screened as linkers and enzymatic transglycosylation was examined under several conditions. In the case of 2-hydroxy-5-nitro-benzyl connected substrate 40, an indication of the occurrence of intramolecular transglycosylation was observed, and the desired product (58) was obtained in 26% isolated yield. The same reaction in the presence of CMP sialic acid and α-(2[Formula: see text]6)-sialyltransferase gave sialyl LacNAc 87 in one pot in 39% isolated yield. Additionally, the effect of the C-2 substituent of the acceptor component was briefly examined using substrates containing NHAlloc (72), NHTroc (73), and N3(74) groups. Although the occurrence of intramolecular transglycosylation was not clear in these cases, disaccharides 8183 were obtained in reasonable yields.Key words: galactosidase, intramolecular transglycosylation, N-acetyllactosamine, sialyltransferase.
为了高效制备N-乙酰乳糖胺(Galβ(1[Formula: see text]4)GlcNAc,LacNAc),探索了β-半乳糖苷酶介导的转糖基化,使用新型底物枯草杆菌环状芽孢杆菌。为了使转糖基化在熵上有利于水解,供体(乳糖或半乳糖)和受体(N-乙酰葡萄糖胺,GlcNAc)组分连接到单个分子上。为此,筛选了1,2-和1,3-苯二甲醇以及2-羟基-5-硝基-和5-羟基-2-硝基苄醇作为连接剂,并在几种条件下研究了酶促转糖基化。在2-羟基-5-硝基苄连接底物40的情况下,观察到了分子内转糖基化的迹象,并以26%的分离产率获得了期望产物(58)。在CMP唾液酸和α-(2[Formula: see text]6)-唾液酰基转移酶存在的情况下,同一反应在一个锅中以39%的分离产率得到了唾液酰基LacNAc 87。此外,简要考察了受体组分的C-2取代基的影响,使用含有NHAlloc(72)、NHTroc(73)和N3(74)基团的底物。尽管在这些情况下分子内转糖基化的发生并不明确,但获得了8183的二糖以合理的产率。关键词:半乳糖苷酶,分子内转糖基化,N-乙酰乳糖胺,唾液酰基转移酶。