Börnke Frederik, Hajirezaei Mohammad, Sonnewald Uwe
Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany.
J Biotechnol. 2002 Jun 13;96(1):119-24. doi: 10.1016/s0168-1656(02)00042-1.
Palatinose (isomaltulose, 6-O-alpha-D-glucopyranosyl-D-fructose) is a structural isomer of sucrose with very similar physico-chemical properties. Due to its non-cariogenicity and low calorific value it is an ideal sugar substitute for use in food production. Palatinose is produced on an industrial scale from sucrose by an enzymatic rearrangement using immobilized bacterial cells. To explore the potential of transgenic plants as alternative production facilities for palatinose, a chimeric sucrose isomerase gene from Erwinia rhapontici under control of a tuber-specific promoter was introduced into potato plants. The enzyme catalyses the conversion of sucrose into palatinose. Expression of the palI gene within the apoplast of transgenic tubers led to a nearly quantitative conversion of sucrose into palatinose. Despite the soluble carbohydrates having been altered within the tubers, growth of palI expressing transgenic potato plants was indistinguishable from wild type plants. Therefore, expression of a bacterial sucrose isomerase provides a valid tool for high level palatinose production in storage tissues of transgenic crop plants.
帕拉金糖（异麦芽酮糖，6-O-α-D-吡喃葡萄糖基-D-果糖）是蔗糖的结构异构体，具有非常相似的物理化学性质。由于其非致龋性和低热值，它是食品生产中理想的糖替代品。帕拉金糖是通过使用固定化细菌细胞进行酶促重排，从蔗糖工业规模生产的。为了探索转基因植物作为帕拉金糖替代生产设施的潜力，将来自雷蒙德氏欧文氏菌的嵌合蔗糖异构酶基因在块茎特异性启动子的控制下导入马铃薯植株。该酶催化蔗糖转化为帕拉金糖。palI基因在转基因块茎的质外体中的表达导致蔗糖几乎定量地转化为帕拉金糖。尽管块茎内的可溶性碳水化合物发生了改变，但表达palI的转基因马铃薯植株的生长与野生型植株没有区别。因此，细菌蔗糖异构酶的表达为转基因作物贮藏组织中高水平生产帕拉金糖提供了一个有效的工具。
