INTERACTIONS OF INVERTASE WITH TANNIC-ACID, HYDROXYALUMINUM (OH-A1) SPECIES OR MONTMORILLONITE
INTERACTIONS OF INVERTASE WITH TANNIC-ACID, HYDROXYALUMINUM (OH-A1) SPECIES OR MONTMORILLONITE
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DOI：
10.1016/0038-0717(93)90106-l
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发表时间：
1993-06-01
影响因子：
9.7
通讯作者：
VIOLANTE, A
中科院分区：
文献类型：
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作者：
GIANFREDA, L;RAO, MA;VIOLANTE, A
研究了转化酶、单宁酸和羟基铝(OH-Al)聚合物之间的相互作用，考察了它们对酶活性的影响和活性酶复合体的形成。当单宁酸浓度大于1.25 mM时，转化酶活性受到抑制(抑制常数K(I)=133 mM)，而抑制作用显著(~gt；90%)。V(Max)和K(M)值分别反映了OH-Al物种和单宁酸的纯非竞争性和混合型抑制机理。根据孵育时间和单宁酸与酶的比例，转化酶和单宁酸之间的相互作用产生了可溶和不溶的络合物，表现出活性水平的降低。转化酶活性的降低是单宁酸/转化酶比值和接触时间的函数。在络合过程中，OH-Al聚合物的存在大大增加了转移酶与单宁酸之间的键合，提高了固定化酶的残余活力。更多的活性转化酶分子被从溶液中去除，并观察到活性转化酶-单宁酸络合物的增强沉淀。显然，不仅OH-Al离子促进了具有不同结构特征的单宁酸-转化酶络合物的絮凝，而且它们与单宁酸分子的相互作用导致了具有不同电荷和吸附位置的铝沉淀产物。此外，还将转化酶-羟基-铝-单宁酸络合物固定在蒙脱石表面，形成的络合物具有较高的酶活性。OH-Al物种作为丹宁酸分子和蒙脱石表面之间的桥梁，也促进了可溶性转移酶-OH-Al-丹宁酸络合物的固定化。
Interactions between invertase, tannic acid and hydroxy-aluminium (OH-Al) polymers were investigated with regard to their influence on enzyme activity and the formation of active enzymatic complexes. OH-Al species slightly inhibited invertase activity (inhibition constant, K(i) = 133 mm) whereas a marked inhibition (> 90%) was detected at a tannic acid concentration greater than 1.25 mm. The V(max) and K(m) values indicated a pure non-competitive and a mixed-type inhibition mechanism of OH-Al species and tannic acid, respectively. Depending on the incubation time and the tannic acid-to-enzyme ratio, the interaction between invertase and tannic acid yielded both soluble and insoluble complexes, which displayed reduced activity levels. The decrease of invertase activity was a function of both the tannic acid-to-invertase ratios and the contact time. Bonding between invertase and tannic acid as well as the residual activity of the immobilized enzyme were greatly increased by the presence of OH-Al polymers during the complexation process. Many more active invertase molecules were removed from solution and an enhanced precipitation of active invertase-tannic acid complexes was observed. Clearly not only OH-Al ions facilitated flocculation of tannate-invertase complexes with different structural characteristics but their interaction with tannic acid molecules gave rise to Al precipitation products having a different charge and sorption sites. Furthermore, an invertase-OH-Al-tannic acid complex was anchored on montmorillonite surfaces and the complex formed showed a relatively high enzymatic activity. OH-Al species acting as bridges between tannate molecules and montmorillonite surfaces also facilitated the immobilization of soluble invertase-OH-Al-tannate complexes.