小麦叶绿素酶生化动力学特性研究

Studies on properties of biochemical kinetics of chlorophyllase from wheat seedlings

采用分光光度法对小麦Chlase的生化性质及其动力学特征进行了部分研究.结果表明:Chlase的Km值为11.6μmol/L,Vmax为1.14μmol·min-1·g-1FW;最适pH为7.5,pH在7～8的范围内,Chlase催化Chl脱植基反应的活性较高;最适温度为45℃,在60℃、70℃、80℃保温时,该酶活力丧失50%所需的时间分别为27min、22min、18min;研究发现不同的金属离子及络合剂对该酶活性有影响,低浓度的Ca2+、Zn2+和较高浓度的Mg2+对Chlase有激活作用,而Fe3+、EDTA则较明显地抑制了Chlase活性;Chlase可催化Chla、b的脱植基反应,对Chlb的亲和性较高.

Until very recently, the phenomenon of chlorophyll breakdown in plants was considered as a major biological enigma. Chlorophyllase was one of the most important members of enzymes in chlorophyll enzymatic degradation. Properties of chlorophyllase from excised wheat leaves were studied. The optimum pH of the enzyme was 7.5. The Km value for chlorophyll was about 11.6 μmol/L and the Vmax value for chlorophyll was 1.14 μmol·min-1·g-1FW. The optimum temperature of the enzyme was about 45 ℃. The halflife of chlorophyllase activities was different at different high temperature. When being incubated at 60℃?70℃?80 ℃, chlorophyllase could lose its half activities within 27 minutes,22 minutes,18 minutes. With different Chl, chlorophyllase showed different kinetic properties. Different ions were found having different effects on chlorophyllase activities. 