Plant Physiology Research Group, Department of Biology, University of Calgary, T2N 1N4, Calgary, Alta., Canada.
Planta. 1983 Apr;157(3):274-7. doi: 10.1007/BF00405194.
Isolated endosperms of Grand Rapids lettuce (Lactuca sativa L.) seeds undergo extensive cell-wall degradation and sugars are released into the surrounding incubation medium. One sugar so released is galactose. α-Galactosidase (EC 3.2.122) is present at the same level in both dry and imbibed isolated endosperms and is responsible for the release of galactose. However, this enzyme does not act upon the native endosperm cell wall, but requires first its partial hydrolysis and the production of oligomers by the action of endo-β-mannanase (EC 3.2.1.787). Galactose is then cleaved from these oligomers, allowing their further subsequent hydrolysis by endo-β-mannanase. Thus α-galactosidase and endo-β-mannanase act cooperatively to effect the hydrolysis of the lettuce endosperm cell walls.
格兰德河莴苣（生菜）种子的孤立胚乳经历广泛的细胞壁降解，糖被释放到周围的孵育介质中。释放的一种糖是半乳糖。α-半乳糖苷酶（EC 3.2.1.22）在干燥和吸胀的孤立胚乳中水平相同，负责释放半乳糖。然而，这种酶不能作用于天然胚乳细胞壁，而是需要首先通过内切-β-甘露聚糖酶（EC 3.2.1.787）的作用将其部分水解并产生低聚物。然后从这些低聚物中切割半乳糖，允许内切-β-甘露聚糖酶进一步水解它们。因此，α-半乳糖苷酶和内切-β-甘露聚糖酶协同作用以水解生菜胚乳细胞壁。
