Morohashi Y, Matsushima H
Department of Regulatory Biology, Faculty of Science, Saitama University, Urawa, Saitama 338-8570, Japan.
J Exp Bot. 2000 Aug;51(349):1381-7.
Laminarin-hydrolysing activity developed in the endosperm of tomato (Lycopersicon esculentum) seeds following germination. The enzyme was basic (pI>10) and the apparent molecular mass was estimated to be 35 kDa by SDS-PAGE. It was specific for linear beta-1,3-glucan substrates. Laminarin was hydrolysed by the enzyme to yield a mixture of oligoglucosides, indicating that the enzyme had an endo-action pattern. Thus, the enzyme was identified as beta-1,3- endoglucanase (EC 3.2.1.39). The activity of the enzyme developed in the endosperm after radicle protrusion (germination) had occurred and the enzyme activity was localized exclusively in the micropylar region of the endosperm where the radicle had penetrated. When the lateral endosperm region, where no induction of the enzyme occurred, was wounded (cut or punctured), there was a marked enhancement of beta-1,3-glucanase activity. Thus the post-germinative beta-1, 3-glucanase activity in the micropylar endosperm portion might be brought about by wounding resulting from endosperm rupture by radicle penetration.
番茄（Lycopersicon esculentum）种子萌发后，胚乳中产生了海带多糖水解活性。该酶呈碱性（pI>10），通过SDS-PAGE估计其表观分子量为35 kDa。它对线性β-1,3-葡聚糖底物具有特异性。该酶可将海带多糖水解产生低聚糖混合物，表明该酶具有内切作用模式。因此，该酶被鉴定为β-1,3-内切葡聚糖酶（EC 3.2.1.39）。胚根突出（萌发）后，胚乳中该酶的活性开始产生，且酶活性仅定位于胚根穿透的胚乳珠孔区域。当未诱导该酶产生的胚乳外侧区域受到损伤（切割或穿刺）时，β-1,3-葡聚糖酶活性显著增强。因此，胚乳珠孔部分萌发后的β-1,3-葡聚糖酶活性可能是由胚根穿透导致胚乳破裂造成的损伤引起的。
