Michalczuk L, Bandurski R S
Biochem J. 1982 Nov 1;207(2):273-81. doi: 10.1042/bj2070273.
An enzyme fraction from extracts of immature kernels of Zea mays catalyses the formation of 1-O-indol-3-ylacetyl-beta-D-glucose from indol-3-ylacetic acid and UDP-glucose. A second enzyme fraction catalyses the formation of indol-3-ylacetyl-myo-inositol from 1-O-indol-3-ylacetyl-beta-D-glucose and myo-inositol. To our knowledge, this is the first example of hydroxy-group acylation by a 1-O-acyl sugar. The following reaction sequence is proposed: Indol-3-ylacetic acid + UDP-glucose leads to indol-3-ylacetylglucose + UDP (1) Indol-3-ylacetylglucose + myo-inositol leads to indol-3-ylacetyl-myo-inositol + glucose (2) The enzyme catalysing reaction (1) is called UDP-glucose:indol-3-ylacetate glucosyl-transferase (indol-3-ylacetylglucose synthase), and that catalysing reaction (2) is indol-3-ylacetylglucose:myo-inositol indol-3-ylacetyltransferase (indol-3-ylacetyl-myo-inositol synthase). We further show that indol-3-ylacetylglucose synthase is specific for UDP-glucose and, at the stage of purity tested, the enzyme will use either indol-3-ylacetic acid or naphthalene-1-acetic acid, but not 2.4-dichlorophenoxyacetic acid, as glucose acceptor. The indol-3-ylacetyl-myo-inositol synthase is specific for indol-3-ylacetyl-glucose and will not use naphthalene-1-acetylglucose as substrate, and it is specific for myo-inositol among the alcohol acceptors tested. Thus, of the auxins tested, only indol-3-ylacetic acid forms the myo-inositol ester.
来自玉米未成熟籽粒提取物的一种酶组分催化由吲哚 - 3 - 乙酸和UDP - 葡萄糖形成1 - O - 吲哚 - 3 - 基乙酰基 - β - D - 葡萄糖。第二种酶组分催化由1 - O - 吲哚 - 3 - 基乙酰基 - β - D - 葡萄糖和肌醇形成吲哚 - 3 - 基乙酰基 - 肌醇。据我们所知,这是1 - O - 酰基糖进行羟基酰化的首个实例。提出了以下反应序列:吲哚 - 3 - 乙酸 + UDP - 葡萄糖 → 吲哚 - 3 - 基乙酰葡萄糖 + UDP(1)吲哚 - 3 - 基乙酰葡萄糖 + 肌醇 → 吲哚 - 3 - 基乙酰基 - 肌醇 + 葡萄糖(2)催化反应(1)的酶称为UDP - 葡萄糖:吲哚 - 3 - 乙酸葡萄糖基转移酶(吲哚 - 3 - 基乙酰葡萄糖合酶),催化反应(2)的酶是吲哚 - 3 - 基乙酰葡萄糖:肌醇吲哚 - 3 - 基乙酰转移酶(吲哚 - 3 - 基乙酰基 - 肌醇合酶)。我们进一步表明,吲哚 - 3 - 基乙酰葡萄糖合酶对UDP - 葡萄糖具有特异性,并且在测试的纯度阶段,该酶将使用吲哚 - 3 - 乙酸或萘 - 1 - 乙酸作为葡萄糖受体,但不使用2,4 - 二氯苯氧乙酸。吲哚 - 3 - 基乙酰基 - 肌醇合酶对吲哚 - 3 - 基乙酰 - 葡萄糖具有特异性,不会使用萘 - 1 - 乙酰葡萄糖作为底物,并且在测试的醇类受体中对肌醇具有特异性。因此,在所测试的生长素中,只有吲哚 - 3 - 乙酸形成肌醇酯。