Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6.
Plant Physiol. 1978 Nov;62(5):713-7. doi: 10.1104/pp.62.5.713.
The distribution of alpha-galactosidase (alpha-d-galactoside galactohydrolase [EC 3.2.1.22]) in Cucurbita pepo has been determined in an attempt to assess its involvement in hydrolysis of transport sugars of the raffinose oligosaccharide series (alpha-1-6-0-galactopyranosyl sucrose). Extracts prepared from leaves and petioles at different stages of development, roots, flowers, dry and germinating seeds, all contained appreciable levels of alpha-galactosidase activity. Chromatography of these extracts on DEAE-Sephadex resolved the enzyme into three active isozymic forms. These isozymes were present in all regions of the plant analyzed but their relative proportions varied between tissues and changed within leaf and petiole tissues during development and in seeds during their germination. The level of total alpha-galactosidase activity in the leaf blade measured on a fresh weight or total protein basis remained constant at all developmental stages analyzed. The occurrence of these isozymes in mature exporting leaves indicates an effective intracellular compartmentation between their location and the sites of galactosyl oligosaccharide biosynthesis, accumulation and movement in the tissue. We have used these results to comment on the transport pathway of galactosyl oligosaccharides between the phloem and surrounding tissues in this plant.
已测定葫芦科植物中α-半乳糖苷酶（α-d-半乳糖苷半乳糖水解酶[EC3.2.1.22]）的分布情况，以评估其在分解棉子糖寡糖系列（[α-1-6-0-半乳糖吡喃糖苷基]（n）蔗糖）的运输糖中的作用。从发育不同阶段的叶片和叶柄、根、花、干种子和发芽种子中提取的提取物均含有相当水平的α-半乳糖苷酶活性。这些提取物在 DEAE-葡聚糖上的色谱分离将酶分为三种活性同工酶形式。这些同工酶存在于分析的植物所有区域，但它们的相对比例在组织之间以及叶片和叶柄组织的发育过程中和种子在发芽过程中发生变化。在分析的所有发育阶段，按鲜重或总蛋白基础测量的叶片中总α-半乳糖苷酶活性水平保持不变。这些同工酶在成熟的输出叶片中的存在表明，它们的位置与组织中半乳糖基寡糖生物合成、积累和运动的部位之间存在有效的细胞内区室化。我们利用这些结果对该植物中半乳糖基寡糖在韧皮部和周围组织之间的运输途径进行了评论。
