A comparative study on wall degrading enzymes, pectin modifications and softening during ripening of selected tropical fruits
A comparative study on wall degrading enzymes, pectin modifications and softening during ripening of selected tropical fruits
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DOI：
10.1016/j.plantsci.2004.03.030
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发表时间：
2004-08-01
期刊：
影响因子：
5.2
通讯作者：
Lazan, H
中科院分区：
文献类型：
--
作者：
Ali, ZM;Chin, LH;Lazan, H
以番茄为对照，研究了快速软化热带水果和缓慢软化热带水果成熟过程中的细胞壁修饰能力和酶组成，发现其含有显著的内切多聚半乳糖醛酸酶(Endo-PG；EC 3.2.1.15)活性。除PG外，代表其果胶和/或半纤维素修饰能力的其他酶是果胶甲基酯酶(EC 3.2.1.11)、β-半乳糖苷酶(EC 3.2.1.23)和(1->；4)-β-半乳糖苷酶(EC 3.2.1.4)。番石榴(Psidium guajava L.)的50%硬度下降时间约为1.5d，番茄(Lycopsicesculentum Mill.)、番木瓜(Mas Banana，AA组)和木瓜(Eksotika番木瓜)分别为3d、4.5d和20d、24d。和柬埔寨番石榴。显著改变细胞壁的能力反映在影响果胶溶解度增加和螯合可溶性果胶解聚的能力上，这种能力随果实类型的不同而明显不同，可能不一定与软化速率相关，也不依赖于任何显著的Endo-PG活性的存在。在成熟的西红柿、芒果和木瓜中进行了广泛的果胶修饰。博蒙特番石榴和玛斯香蕉虽然软化迅速，但果胶降解非常有限，似乎无法与软化缓慢的杨桃和柬埔寨番石榴中发生的修改相提并论。除番茄外，所有供试水果均含有显著的外源PG(EC 3.2.1.67)活性，说明内源PG可能不是果实软化差异的决定因素。所有其他酶，即。果胶甲基酯酶、(1->；4)-β-葡聚糖酶，尤其是β-半乳糖苷酶似乎与果实软化速率的差异有关，并可能对观察到的果实软化速率的差异有显著贡献。(C)2004爱思唯尔爱尔兰有限公司。保留所有权利。
Cell wall modifying capacity and enzyme composition of rapid and slow-softening tropical fruits during ripening were investigated with respect to that of tomato, noted to contain significant endo-polygalacturonases (endo-PG; EC 3.2.1.15) activities. Besides PG, other enzymes selected to represent their pectin and/or hemicellulose modifying potentials were pectin methylesterase (EC 3.2.1.11), beta-galactosidase (EC 3.2.1.23), and (1-->4)-beta-alucanase (EC 3.2.1.4). Time for 50% firmness loss was about 1.5 days for Beaumont guava (Psidium guajava L.), 3 days for tomato (Lycopersicon esculentum Mill.), Mas banana (Musa acuminata, AA group) and Eksotika papaya (Carica papaya L.), 4.5 days for Harumanis mango (Mangifera indica L.), and 20 and 24 days for B 10 carambola (Averrhoa carambola L.) and Kampuchea guava, respectively. Capacity to markedly modify cell walls as reflected by capability to impact increased pectin solubility and depolymerization of chelator-soluble pectin, and which varied markedly with the fruit types, may not necessarily be correlated with softening rate, neither was it dependent on the presence of any significant endo-PG activities. Extensive pectin modifications occurred in ripening tomato, mango and papaya. Beaumont guava and Mas banana, though softened rapidly, experienced much limited pectin degradation, seemingly unable to match the modifications that occur in the slow-softening carambola and Kampuchea guava. All fruits tested, except tomato, contained significant exo-PG (EC 3.2.1.67) activities, thus explaining that endo-PG might not be the determining factor of differential softening. All other enzymes, viz. pectin methylesterase, (1-->4)-beta-glucanase, and in particular, p-galactosidase seemed relevant and might contribute significantly to the observed variations in softening rate amongst the fruits. (C) 2004 Elsevier Ireland Ltd. All rights reserved.