Transferase Activity of Lactobacillal and Bifidobacterial β-Galactosidases with Various Sugars as Galactosyl Acceptors
Transferase Activity of Lactobacillal and Bifidobacterial β-Galactosidases with Various Sugars as Galactosyl Acceptors
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DOI：
10.1021/acs.jafc.5b06009
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发表时间：
2016-03-30
影响因子：
6.1
通讯作者：
Thu-Ha Nguyen
中科院分区：
文献类型：
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作者：
Arreola, Sheryl Lozel;Intanon, Montira;Thu-Ha Nguyen
鲁氏乳杆菌L103(LreuβGal)、德氏乳杆菌亚种的β-半乳糖苷酶。在确定的初始速度条件下，对保加利亚乳杆菌DSM 20081和短双歧杆菌DSM 20281(BBREβGAL-I和BBREβGAL-II)将半乳糖基转移到乳糖及其水解产物D-葡萄糖和D-半乳糖以及某些糖受体如N-乙酰-D-氨基葡萄糖(GlcNAc)、N-乙酰-D-氨基半乳糖(GalNAc)和L岩藻糖(Fuc)上的倾向进行了详细的研究。这些不同的受体(称为亲核体，Nu)的速率常数或分配比(k(Nu)/k(水))被用来衡量某种物质作为这些β-半乳糖苷酶的半乳糖受体的能力。当使用L-β-Gal或Bbre-B-Gal-II时，半乳糖基转移到GlcNAc的能力分别是乳糖的6倍和10倍。在等摩尔底物浓度下，乳糖和GlcNAc催化N-乙酰氨基半乳糖胺的生成，按GlcNAc初始浓度计算，最高产率分别为41%和24%。
The beta-galactosidases from Lactobacillus reuteri L103 (Lreu beta gal), Lactobacillus delbrueckii subsp. bulgaricus DSM 20081 (Lbul beta gal), and Bifidobacterium breve DSM 20281 (Bbre beta gal-I and Bbre beta gal-II) were investigated in detail with respect to their propensity to transfer galactosyl moieties onto lactose, its hydrolysis products D-glucose and D-galactose, and certain sugar acceptors such as N-acetyl-D-glucosamine (GlcNAc), N-acetyl-D-galactosamine (GalNAc), and L-fucose (Fuc) under defined, initial velocity conditions. The rate constants or partitioning ratios (k(Nu)/k(water)) determined for these different acceptors (termed nucleophiles, Nu) were used as a measure for the ability of a certain substance to act as a galactosyl acceptor of these beta-galactosidases. When using Lbul beta gal or Bbre beta gal-II, the galactosyl transfer to GlcNAc was 6 and 10 times higher than that to lactose, respectively. With lactose and GlcNAc used in equimolar substrate concentrations, Lbul beta gal and Bbre beta gal-II catalyzed the formation of N-acetyl-allolactosamine with the highest yields of 41 and 24%, respectively, as calculated from the initial GlcNAc concentration.