发芽咖啡豆α-半乳糖苷酶的性质研究

摘要

[ Objective ] The research aimed to study the enzymatic properties of α-Gal from the germinating coffee bean. [ Method ] α-Gal was ex tracted from the germinating coffee bean. The enzyme activities in the different temperature and pH were studied. Moreover,the optimum tempera ture and pH were determined. The influences of different metal ions and ion strengths (NaCl) on the enzyme activity of α-Gal were studied. Lin eweaver-Burk double reciprocal plot was used to measure Km and Vmax of α-Gal. [ Result]The optimum temperature and pH of α-Gal were respec tively 45 ℃ and 6. 0. The thermal stable temperature range was 20 - 50 ℃ ,and pH stable range was 5.0 - 7.0. The influences of Na+ ,K + ,Mg2+and Cu2+ on the enzyme activity of α-Gal weren' t big. Zn2+ promoted the enzyme activity,and Ba2+ slightly inhibited the enzyme activity. Hg2+ strongly inhibited the activity of α-Gal. When the ion strength (NaCl) was during 0 -0.25 mol/L,the activity of α-Gal Wasn' t affected. By Lineweaver-Burk double reciprocal plot ,Km and Vmax of α-Gal were respectively 0.556 mmol/L and 1.19 μmol/min. [ Conclusion]The research provided the theory guidance for the further application of α-Gal from the germinating coffee bean.%[目的]研究发芽咖啡豆α-半乳糖苷酶的酶学性质.[方法]从发芽咖啡豆中提取α-半乳糖苷酶,研究不同温度和pH下的酶活,并确定该酶的最适温度和pH.研究了不同金属离子和不同离子强度(NaCl)对α-半乳糖苷酶酶活的影响.Lineweaver-Burk双倒数作图法测定该酶的Km和Vmax.[结果]α-半乳糖苷酶的最适温度和pH分别为45 ℃、6.0,热稳定温度范围为20～50 ℃,pH稳定范围为5.0～7.0.Na+、K+、Mg2+和Cu2+对α-半乳糖苷酶酶活的影响不大,Zn2+促进酶活,Ba2+对酶活稍有抑制,Hg2+强烈抑制α-半乳糖苷酶的活性.在0～0.25 mol/L离子强度(NaCI)范围内,α-半乳糖苷酶的酶活不受影响.Lineweaver-Burk双倒数作图法测定该酶的Km和Vmax 分别为0.556 mmol/L、1.19 WnoVmin,[结论]该研究为发芽咖啡豆α-丰乳糖苷酶的进一步应用提供理论指导.