固定化α-葡萄糖苷酶的性质研究

A Study on the Nature of Immobilized α-Glucosidase

研究了以微球形壳聚糖为载体采用吸附 -交联法制备的固定化α_葡萄糖苷酶(简称“ITGL”)的理化特性 .结果表明 ,ITGL的最适 pH值为 4 .5 ,游离酶 (简称“TGL”)的最适 pH值为 5 .0 ;ITGL的最适温度达到 70℃ ,比TGL的提高 5℃ ,并且ITGL的最适作用温度范围显著变宽 ,在 4 0～ 70℃范围内活力较为稳定 ;ITGL的酸碱稳定性、热稳定性和贮存稳定性均比TGL有较大提高 ;TGL和ITGL均对高离子强度和脲不稳定 ;低浓度的Ca2 + 和Mg2 + 对TGL和ITGL的活力均有增强作用 ,而Fe2 + 、Ag+ 、Cu2 + 、Hg2 +对TGL和ITGL的活力均有明显的抑制作用 ;ITGL的操作半衰期可达 2 4d ;以麦芽糖为底物时 ,ITGL的反应动力学参数无显著变化 .

Some properties of the immobilized α_glucosidase (ITGL), which was prepared by adsorbing and crosslinking on spherical microporous chitosan carrier, were compared with the nature one (TGL)'s. The optimum reaction pH of the ITGL was 4.5, while the TGL's was 5.0; its optimum reaction temperature was 70 ℃, which was 5 ℃ higher than that of TGL, and the range of its optimum reaction temperature was 40～70 ℃, and much larger than that of TGL. Its stability for enduring pH changing, heat, and long_time storing was much better than that of TGL. TGL and ITGL were both unstable to high ion intensity and urea. The low concentration of Ca 2+ and Mg 2+ could increase the activity of TGL and ITGL, but Fe 2+ , Ag +, Cu 2+ , and Hg 2+ obviously inhibited the activity of both enzymes. The reaction half_life of ITGL was 24 days. The kinetics constant of ITGL did not obviously change when the substrate was maltose.