Glover H, Brady C
CSIRO Division of Horticulture and Macquarie University, North Ryde, New South Wales, Australia.
Phytochemistry. 1994 Nov;37(4):949-55. doi: 10.1016/s0031-9422(00)89509-6.
Three isoforms of pectin esterase (PE1-PE3) (pectin pectyl-hydrolase, EC 3.1.1.11.) were purified to homogeneity from ripe peach fruit (Prunus persica cv. Coronet). The three enzymes were basic proteins of M(r) 34,000 as determined by denaturing polyacrylamide gel electrophoresis but were separated by FPLC cation-exchange chromatography. The proteins were N-terminally blocked but amino acid sequences were obtained for peptides released from two of the three isoforms. The sequences revealed a threonine/lysine substitution in a comparison between isoform PE2/isoform PE3, and there were regions of sequence similarity with other plant pectin esterases. The proteins did not bind to concanavalin A and were not stained by the periodate-Schiff reagent suggesting a low or zero level of glycosylation. Polyclonal antisera to isoform PE3 also bound to isoforms PE1 and PE2. The study provides the enzyme protein sequence and immunological basis for an evaluation of the role of pectin esterases in normal and abnormal ripening of peach fruit.
从成熟的水蜜桃（Prunus persica cv. Coronet）中纯化出三种同工型果胶酯酶（PE1 - PE3）（果胶果胶酰水解酶，EC 3.1.1.11），使其达到均一状态。通过变性聚丙烯酰胺凝胶电泳测定，这三种酶是分子量为34,000的碱性蛋白质，但通过快速蛋白质液相色谱（FPLC）阳离子交换色谱法可将它们分离。这些蛋白质的N端被封闭，但获得了三种同工型中两种释放出的肽段的氨基酸序列。序列分析显示，在同工型PE2/同工型PE3的比较中存在苏氨酸/赖氨酸取代，并且与其他植物果胶酯酶存在序列相似区域。这些蛋白质不与伴刀豆球蛋白A结合，也不能被高碘酸 - 希夫试剂染色，表明其糖基化水平较低或为零。针对同工型PE3的多克隆抗血清也与同工型PE1和PE2结合。该研究为评估果胶酯酶在水蜜桃果实正常和异常成熟过程中的作用提供了酶蛋白序列和免疫学基础。
