茶多酚对米曲霉α-淀粉酶的回收及其特性的影响

Recovery Studyon Aspergillus Oryzaeα-Amylaseby Tea Polyphenols and Effects on the Properties of α-amylase

研究绿茶中多酚类对米曲霉来源的α-淀粉酶特性的影响。从绿茶中提取茶多酚(TP),对米曲霉α-淀粉酶进行络合、沉淀及回收;以Bernfeild法测定α-淀粉酶与TP络合后,在不同温度、不同pH值、不同底物浓度的活性变化。结果表明:茶多酚对米曲霉α-淀粉酶无活性抑制作用,两者之间具有起混作用;0.3%的茶多酚浓度,获得最大α-淀粉酶活性回收率(约71%);α-淀粉酶与TP络合后,最适反应温度由30～50℃范围变为60～70℃;最适pH值由3.0～8.0变为5.0～6.0;在80℃下,活性变化总趋向与游离的α-淀粉酶相似,180min后能够保存85%的酶活力,但是在前40min,酶活力下降较快;Lineweever—Burk图表明,络合后的α-淀粉酶Km由0.18%变为1.03%(可溶性淀粉底物浓度)。结论:米曲霉α-淀粉酶与TP络合后活性不受抑制并可通过这种络合回收,络合后的α-淀粉酶,最适反应温度及最适pH值变大、变窄;对底物的亲和力下降。

To assess the effects of tea polyphen ols(TP)on the properties ofα-amylase extracted fromAspergillu s Oryzae.α-amylase fromAspergillus Oryzae wa s complexed with TP extracted fromgreen tea.Bernfeild method was adopted to analyze the activities of freeα-amylase and TP complexedα-amylase under various temperature s,pH values and substrate concentration s.It was found that TPwere haze -active and showed no inhibitory effect on theα-amylase.By complex and sedimentati on,the maximum recovery of theα-amylase activity reached about 71%at0.3%TP concentrations.The optimum temperatures for theα-amylase were changed from30～50℃to60～70℃,pHvaluefrom3.0～8.0to5.0～6.0andt heKmvalueoftheα-amylase complexedwithTP from0.18%to1.03%the substrate concentration of solu ble starch.It is concluded that TP re covered the activity of theα-amylase and showed no inhibitory effect by compl exation.After complexed with TP,th e optimumtemperature and pHvalue fo r theα-amylasewereincreasedand narrowe d TheKmvaluewas changedhigherforsolublestarchsubstrate,indicatin gthe decreased affinity of theα-amylase with the substrate.