An acceptor analogue of β-1,4-galactosyltransferase: Substrate, inhibitor, or both?
An acceptor analogue of β-1,4-galactosyltransferase: Substrate, inhibitor, or both?
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DOI：
10.1016/j.carres.2017.08.012
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发表时间：
2017-10-10
影响因子：
3.1
通讯作者：
Wagner GK
中科院分区：
文献类型：
--
作者：
Jiang J;Wagner GK
文献中的许多糖基转移酶抑制剂在结构上衍生自相应酶的供体或受体底物。一个代表性的例子是2-萘基β-d-GlcNAc，一种合成的GlcNAc糖苷，已被报道为半乳糖基转移酶抑制剂。该GlcNAc衍生物作为用于生物学和生物化学研究的化学工具化合物是有吸引力的，因为其报道的作为抑制剂的效力，以及其从容易获得的起始材料的短而直接的合成。我们报道了2-萘基β-d-GlcNAc作为牛乳中β-1，4-半乳糖基转移酶（β-1，4-GalT）的受体底物的行为。这种底物活性以前没有描述过。我们发现，2-萘基β-d-GlcNAc可以是重组表达的β-1，4-GalT和商业批次的相同酶的受体底物，并且在存在和不存在牛血清白蛋白（BSA）的情况下都是如此。正如对完整受体底物的预期，该底物活性具有时间和浓度依赖性。另外的实验表明，所观察到的抑制剂/底物转换是由磷酸酶促进的，磷酸酶是我们的酶偶联糖基转移酶测定的重要组成部分。这些结果表明，2-萘基β-d-GlcNAc和相关受体基糖基转移酶抑制剂的行为强烈依赖于单个测定条件。因此，我们的研究结果对2-萘基β-d-GlcNAc和相关糖苷作为糖生物学和糖生物化学中的工具化合物的使用具有重要意义。已知的β-1，4-半乳糖基转移酶抑制剂GlcNAc β1-（2-萘基）也可以作为受体底物。该受体底物活性通过测定混合物中磷酸酶的存在而促进。提出了一个动力学模型，该模型协调了GlcNAc β1-（2-萘基）的底物和抑制活性。
Many glycosyltransferase inhibitors in the literature are structurally derived from the donor or acceptor substrate of the respective enzyme. A representative example is 2-naphthyl β-d-GlcNAc, a synthetic GlcNAc glycoside that has been reported as a galactosyltransferase inhibitor. This GlcNAc derivative is attractive as a chemical tool compound for biological and biochemical studies because of its reported potency as an inhibitor, and its short and straightforward synthesis from readily available starting materials. We report that in our hands, 2-naphthyl β-d-GlcNAc behaved, unexpectedly, as an acceptor substrate of the inverting β-1,4-galactosyltransferase (β-1,4-GalT) from bovine milk. This substrate activity has not previously been described. We found that 2-naphthyl β-d-GlcNAc can be an acceptor substrate both for recombinantly expressed β-1,4-GalT, and for a commercial batch of the same enzyme, and both in the presence and absence of bovine serum albumin (BSA). As expected for a full acceptor substrate, this substrate activity was time- and concentration-dependent. Additional experiments show that the observed inhibitor/substrate switch is facilitated by a phosphatase that is an essential component of our enzyme-coupled glycosyltransferase assay. These findings suggest that the behaviour of 2-naphthyl β-d-GlcNAc and related acceptor-based glycosyltransferase inhibitors is strongly dependent on the individual assay conditions. Our results therefore have important implications for the use of 2-naphthyl β-d-GlcNAc and related glycosides as tool compounds in glycobiology and glycobiochemistry. The known β-1,4-galactosyltransferase inhibitor GlcNAc β1-(2-naphthyl) can also behave as an acceptor substrate. This acceptor substrate activity is promoted by the presence of a phosphatase in the assay mixture. A kinetic model is proposed that reconciles the substrate and inhibitory activity of GlcNAc β1-(2-naphthyl).
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影响因子：
3
作者：
PALCIC, MM;HEERZE, LD;HINDSGAUL, O
通讯作者：
HINDSGAUL, O
影响因子：
3
作者：
Gao, Yin;Lazar, Carmen;Brockhausen, Inka
通讯作者：
Brockhausen, Inka
影响因子：
8.4
作者：
Siegbahn, Anna;Manner, Sophie;Ellervik, Ulf
通讯作者：
Ellervik, Ulf
影响因子：
15
作者：
LEMIEUX, RU;BUNDLE, DR;BAKER, DA
通讯作者：
BAKER, DA
影响因子：
14.8
作者：
Pesnot, Thomas;Jorgensen, Rene;Palcic, Monica M.;Wagner, Gerd K.
通讯作者：
Wagner, Gerd K.