An Aspartic Type Protease Degrades Trypsin Inhibitors, the Major Root Storage Proteins of Sweet Potato (Ipomoea batatas (L.)Lam cv. Tainong 57)

以發芽的台農57號甘藷塊根（已去除芽）純化水解其塊根儲藏性蛋白質—胰蛋白酶抑制因子的蛋白酶。市售的pepstatin-agarose (crosslinked, 6%)作爲親和性管柱層析膠體純化蛋白酶。在gelatin-SDS-PAGE活性染色膠體結果顯示，此蛋白酶受到pepstatin抑制，但不受E-64的抑制。推測此蛋白酶是屬於天冬胺酸型，其分子量大約是64kDa。使用胰蛋白質抑制因子的活性染色膠體的結果來顯示胰蛋白酶抑制因子水解情形，結果顯示，有沒有5mM DTT存在下，此天冬胺酸型蛋白酶都可以水解胰蛋白酶抑制因子，有5mM DTT存在下，此天冬胺酸型蛋白酶幾乎可以完全水解胰蛋白酶抑制因子。此一天冬胺酸型蛋白酶水解胰蛋白酶抑制因子在生理意義將在文中討論。

關鍵字

天冬胺酸型蛋白酶；水解；生理意義；甘藷；胰蛋白酶抑制因子

並列摘要

Roots of sprouted sweet potato (Ipomoea batatas [L.] Lam) were used as materials to purify proteases which degraded trypsin inhibitors (TIs), the root storage proteins of sweet potato (SP). The commercial pepstatinagarose (crosslinked, 6%) was chosen as an affinity column for purification. The purified protease has a molecular mass of about 64 kDa on the gelatin-SDS-PAGE gel and was inhibited by pepstatin but not by E-64 on the gelatinSDS-PAGE gel. Therefore, it might belong to the aspartic type. Using the trypsin inhibitor activity staining method as a criterion for TI degradations, we found that this aspartic type protease could degrade purified TIs in the presence or absence of 5 mM DTT and the hydrolysis was complete in the former condition. The physiological role of aspartic type protease in the degradation of SPTIs is discussed.

並列關鍵字

Aspartic type protease ； Degradation ； Physiological role ； Sweet potato ； Trypsin inhibitor

國際替代計量

An Aspartic Type Protease Degrades Trypsin Inhibitors, the Major Root Storage Proteins of Sweet Potato (Ipomoea batatas (L.)Lam cv. Tainong 57)

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