Department of Vegetable Crops, Cornell University, Ithaca, New York 14853.
Plant Physiol. 1980 Sep;66(3):451-6. doi: 10.1104/pp.66.3.451.
Binding between potato tuber invertase and its endogenous inhibitor followed second-order reaction kinetics. Binding rates were diminished by the presence of various inorganic salts, MgCl(2) being especially effective. This effect of MgCl(2) was used in binding rate studies by adding the salt with sucrose to reduce binding during assay of previously unbound activity. The optimal pH for binding was about 4.8, similar to the optimal pH for catalytic activity of invertase. The optimal temperature for binding was about 45 C, approximately 5 C less than the optimum for catalytic activity. Sucrose at concentrations as low as 2 millimolar slowed binding; reducing sugars had little or no effect on binding or on catalytic activity.
马铃薯块茎转化酶与其内源性抑制剂的结合遵循二级反应动力学。各种无机盐的存在会降低结合速率,其中 MgCl₂ 的效果尤为显著。在结合速率研究中,通过在测定之前未结合的活性时加入该盐与蔗糖,利用 MgCl₂ 的这种作用来减少结合。结合的最佳 pH 值约为 4.8,与转化酶催化活性的最佳 pH 值相似。结合的最佳温度约为 45°C,比催化活性的最适温度低约 5°C。浓度低至 2 毫摩尔的蔗糖会减缓结合;还原糖对结合或催化活性几乎没有影响。