野生苋属植物籽实中新型α淀粉酶抑制剂的分离纯化及其性质研究(英文)

Purification and Characterization of a Novel α-Amylase Inhibitor from Wild Amaranth(Amaranthus paniculatus)Weeds

从野生苋属植物 (Amaranthuspaniculatus)籽实中分离纯化出α淀粉酶的一种新型蛋白质类抑制剂 .该抑制剂被命名为WAI 1 .MALDI TOF质谱测得其分子量为 986 5 ,是目前报道的α 淀粉酶的蛋白质类抑制剂中分子量最小的 .初步的组成和结构分析结果表明 ,WAI 1由 9个氨基酸残基组成 ,其N端为焦谷氨酸 .直接用RP HPLC纯化后 ,WAI 1能在弱酸性条件下 ,以非竞争性抑制作用方式有效抑制美洲蜚蠊消化道α淀粉酶的活性 ,最适抑制pH 6 0 ,但对人唾液淀粉酶活性无影响 .WAI 1在 37℃下与酶预温浴约 30min后显示最大抑制活性 .当α淀粉酶用量一定时 ,α淀粉酶活性的抑制率在约 5 0 %的范围内随抑制剂 酶比例的增大而呈线性增加 ,超过 5 0 %后 ,抑制率随抑制剂 酶比例的增大而缓慢上升 ,最终达到最大值 (约 6 5 % ) .

A novel proteinaceous inhibitor of α amylase was purified from the wild amaranth ( Amaranthus paniculatus ) seeds. The inhibitor, named WAI 1,has a molecular weight of 986 5 determined by MALDI TOF mass spectrometry. It is the smallest proteinaceous inhibitor of α amylase found so far. Preliminary compositional and structural analysis indicated that WAI 1 is a nonapeptide with N terminal pyroglutamate. Purified directly by reversed phase HPLC, WAI 1 potently inhibited the α amylase activity of the insect (Periplaneta Americana ) digestive duct in a noncompetitive manner and did not inhibit the human salivary α amylase. WAI 1 inhibited α amylase activity of Periplaneta Americana digestive duct evidently under mild acid conditions, with optimal inhibitory pH 6 0. WAI 1 exhibited the highest inhibitory activity after preincubation with the enzyme at 37℃ for about 30?min. When a fixed amount of α amylase used, along with the increase of the inhibitory/enzyme ratio the inhibition percentages of the α amylase activity were linearly increased up to about 50%, and then increased slowly up to a maximum of about 65%.