发酵产物对灰绿曲霉β-葡萄糖苷酶活力的影响  

Effects of Fermentation Products on β-glucosidase fromAspergillus glaucus

作　　者：许鑫琦 任跃明[2] 马素娟[1] 龙敏南[3] 陈清西[1] 

机构地区：[1]厦门大学生命科学学院,福建厦门361102 [2]国家药典委员会,北京100061 [3]厦门大学能源研究院,福建厦门361102

出　　处：《厦门大学学报（自然科学版）》2014年第1期115-119,共5页Journal of Xiamen University：Natural Science

基　　金：国家重点基础研究发展计划(973)项目(2010CB732201);福建省自然科学基金(2009J01196)

摘　　要：从自行筛选出的灰绿曲霉XC-9菌株的发酵液得到活力较高的纤维素酶,分离纯化出其中的β-葡萄糖苷酶(BG).探讨发酵产物对酶活力的影响,乙醇、乙酸、乳酸对酶活力有不同程度抑制,抑制强度依次为乳酸>乙酸>乙醇,其半抑制浓度(IC50)分别为0.09,0.34和4.4mol/L.它们对BG的抑制作用均表现为非竞争性可逆抑制,抑制常数分别为0.7%(0.083mol/L)、2%(0.315mol/L)、26%(4.25mol/L),实验结果表明它们不是结合在酶活性中心的底物结合部位上,而是结合在其以外的必需基团上抑制酶活力.随着乙醇浓度上升,BG最适反应温度逐渐降低,乙醇达到20%(体积分数,下同)时,BG最适温度由60℃降到50℃.在低体积分数乙醇溶液(小于16%)中的BG活力高过无乙醇溶液中的BG活力.荧光光谱分析表明,高浓度乙醇可使BG分子构象松散,导致变构失效.该研究为纤维素酶发酵进程控制提供了理论依据.In this paper,we studied the effects of fermentation products,ethanol,acetic acid and lactic acid,on the activity BG fromAspergillus glaucus.These products showed obvious inhibition on BG activity and the inhibitor concentration leading to 50%activity lost(IC50) was determined to be 4.4,0.34and 0.09mol/L,respectively.The inhibition mechanisms of these products all belonged to a noncompetitive reversible reaction,and the constants of inhibition(KI)was 26%(4.25mol/L),2%(0.315mol/L)and 0.7%(0.083mol/L),respectively.The performance of ethanol on BG got further studied.Increasing the concentration of ethanol,we found that the optimum temperature for BG activity decreased,which is 60℃in 0%ethanol declined to 50℃in 20%,and when reaction temperature was low,BG in the solution that contained small amount of ethanol(<16%)showed higher activity than that in ethanol-free solution.Comparison with the results from fluorescence emission spectroscopy revealed that ethanol lead to conformational changes of BG in 60℃,pH 3.6solution.Our study gave theoretical support for the industry of cellulose-fermentation for ethanol.

关 键 词：灰绿曲霉 Β-葡萄糖苷酶 发酵产物 构象 

分 类 号：Q356.1[生物学—遗传学]