- 學位論文
甘藷塊根主要儲藏性蛋白質及其水解物抗氧化活性的研究
Antioxidant activities of the major root storage proteins of sweet potato 〔Ipomoea batatas (L.) Lam〕 and their hydrolysates
摘要
胰蛋白酶抑制因子（TIs），為甘藷塊根中主要儲藏性蛋白質。本研究以trypsin-Sepharose 4B 親和管柱層析方法，從台農57號甘藷塊根和台農65號甘藷 (Ipomoea batatas [L.] Lam) 塊根中純化出TIs。藉由一系列抗氧化DHR123活性試驗，如清除DPPH自由基、清除hydroxyl自由基、還原力的測定、清除超氧自由基的測定、抗低密度脂蛋白氧化、抑制peroxynitrite氧化和保護DNA氧化等研究，都顯示TIs具有抗氧化活性。我們經由iodoacetamide修飾半胱胺酸殘基及以NBSI (N-bromosuccinimide)修飾色胺酸側鏈後進行抗氧化活性試驗，發現TIs中半胱胺酸殘基和色胺酸側鏈分別對清除DPPH自由基及清除hydroxyl自由基有明顯影響。其中半胱胺酸殘基對清除DPPH自由基的抗氧化活性有很大的影響。而我們分別以胃蛋白酶，pronase E和胃蛋白酶水解產物再以凝乳胰蛋白酶水解TIs，分別做清除DPPH自由基，對抗低密度脂蛋白氧化，了解其不同抗氧化活性。再將TIs水解產物以Sephadex G-50 進行管柱層析分離。並將分離的水解產物進行清除hydroxyl自由基活性試驗。結果顯示，小分子胜肰仍然具有清除hydroxyl自由基能力。
並列摘要
Trypsin inhibitors (TIs), the major root storage protein of sweet potato, were purified from different cultivars of Tainong 57 and Tainong 65 of sweet potato (Ipomoea batatas [L.] Lam) roots by trypsin-Sepharose 4B affinity column. By series of in vitro tests, including DPPH radicals and hydroxyl radicals scavenging activity assays, reducing power test, anti-superoxide radicals assay, anti-human low density lipoprotein (LDL) oxidation test, protections against hydroxyl radical- mediated DNA damages and peroxynitrite medialed dihydrohodamine oxidation, it was showed that TIs exhibited antioxidant and antiradical activities compared with positive controls. Modifications of cysteine residues by iodoacetamide or tryptophan residues by NBSI (N-bromosuccinimide) in TIs, it was showed that tryptophan residues contributed greatly and cysteine residues partially against hydroxyl radicals; however, cysteine residues contributed largely DPPH radical scavenging activities. Using TIs as materials for pepsin, pronase E or pepsin successively by chymotrypsin hydrolysis, it was showed that all of the hydrolysates still had antioxidant activity against DPPH radicals, anti-human LDL oxidation activity and protections against hydroxyl radicals mediated DNA damges. The peptides distributions of hydrolystates were separated by Sephadex G-50 column. Each fraction was determined for hydroxyl radical scavenging activities. It was showed that the small molecular fractions still had activities against hydroxyl radicals.
參考文獻
延伸閱讀
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