Comparison of the catalytic and physical properties of the components of lyophilized beef erythrocyte catalase with those of lyophilized beef liver catalase components.
Comparison of the catalytic and physical properties of the components of lyophilized beef erythrocyte catalase with those of lyophilized beef liver catalase components.
复制标题
冻干牛红细胞过氧化氢酶组分与冻干牛肝过氧化氢酶组分的催化和物理性质比较。
DOI：
10.1016/0003-9861(69)90102-7
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发表时间：
1969
影响因子：
3.9
通讯作者：
A. L. Dounce
中科院分区：
文献类型：
--
作者：
A. Deisseroth;A. L. Dounce
研究了冻干牛红细胞过氧化氢酶组分的催化和物理性质，并与我们以前报道的冻干牛肝过氧化氢酶组分的催化和物理性质进行了比较（10）。组分I的分子量比天然过氧化氢酶沉淀得慢得多，在牛肉红细胞和肝过氧化氢酶经过冻干的情况下为81，000 - 82，000。组分II是我们在冻干红细胞过氧化氢酶中发现的唯一的另一组分，分子量为217，000 - 244，000，与天然红细胞过氧化氢酶的分子量接近，组分I和组分II是根据它们在0.1M磷酸盐缓冲液-15%NaCl中的溶解度分离的。连二亚硫酸盐处理的组分II的光谱分析表明，该全分子级分的60-70%是不可还原的过氧化氢酶，而酶测定表明该级分具有aKat。f.为天然过氧化氢酶的10-20%。组分I的分子量是天然红细胞过氧化氢酶的三分之一，通常可被连二亚硫酸盐完全还原，并且在405 mμ处的摩尔消光系数是天然过氧化氢酶和组分II的四分之一。天然牛肉红细胞过氧化氢酶和冻干红细胞过氧化氢酶组分I和II在405 m μ处的消光系数与相应肝过氧化氢酶制剂在405 mμ处的消光系数之比在所有情况下均接近1.5。该值反映了红细胞酶的更大的血红素含量。结果表明，牛红细胞和牛肝过氧化氢酶在冻干过程中，部分酶解离成第三分子，部分酶构象发生变化，被连二亚硫酸盐还原，其催化活性为天然酶活性的1/6 ~ 1/2 3。在大多数情况下，组分II的催化活性大于组分I的催化活性，并且在1/5至1/4之间变化。从作为结晶板的水性悬浮液或作为缓冲溶液冻干的牛红细胞过氧化氢酶获得的组分I的催化活性如此低，以至于被认为是零，正如从作为水性悬浮液冻干的牛肝过氧化氢酶获得的组分I的情况一样。晶体板、棱柱的悬浮液或缓冲溶液。通过冻干红细胞过氧化氢酶棱柱的水悬浮液获得的牛肉红细胞过氧化氢酶第三分子具有可变但可能显著的催化活性，其可以高达天然酶中发现的催化活性的十四分之一。有人提出，红细胞过氧化氢酶第三分子中催化活性的存在可能是由于与肝脏亚基相比，红细胞亚基中高铁血红蛋白含量增加。可能的影响，上述研究结果的一个假设模型的催化作用的过氧化氢酶涉及协调行动的两个或两个以上的血红素进行了讨论。
The catalytic and physical properties of the components of lyophilized beef erythrocyte catalase have been studied, and compared to those of lyophilized beef liver catalase which were reported by us previously (10). The molecular weight of Component I, which sediments much more slowly than native catalase, is 81,000–82,000 in the case of beef erythrocyte and liver catalase subjected to lyophilization. Component II, the only other component found by us in lyophilized erythrocyte catalase, has a molecular weight of 217,000–244,000, which is close to that of native erythrocyte catalase.Comonent I and Component II have been separated on the basis of their solubility in 0.1 M phosphate buffer-15% NaCl. Spectral analysis of dithionite-treated Component II shows that 60–70% of this whole molecule fraction is nonreducible catalase, while enzyme assay shows that this fraction has aKat. f.of 10–20% that of native catalase. Component I, which has one-third the molecular weight of native erythrocyte catalase, usually is completely reducible by dithionite and has a molar extinction coefficient at 405 mμ which is one-quarter that of native catalase and Component II. The ratio of the extinction coefficients at 405 mμ of native beef erythrocyte catalase and Components I and II of lyophilized erythrocyte catalase to the extinction coefficients at 405 mμ of the corresponding liver catalase preparations is in all cases close to 1.5. This value reflects the greater hematin content of the erythroeyte enzyme. It is concluded from the above results that during the lyophilization of beef erythrocyte and beef liver catalases, some of the enzyme is dissociated into third molecules, while a portion of the remainder is modified in conformation, leading to its becoming reducible by dithionite.The catalytic activity of lyophilized erythrocyte catalase varied from one-sixth to one-twenty-third of the activity of the native enzyme. The catalytic activity of Component II in most cases was greater than that of Component I and varied from one-fifth to one-tenth of the native enzyme.The catalytic activity of Component I obtained from beef erythrocyte catalase lyophilized as an aqueous suspension of crystalline plates or as a buffered solution was so low as to be considered zero as was the case with Component I obtained from beef liver catalase lyophilized as an aqueous suspension of crystalline plates, prisms, or as a buffered solution. Beef erythrocyte catalase third molecules obtained through the lyophilization of an aqueous suspension of erythrocyte catalase prisms possess variable but possibly significant catalytic activity, which can be as high as one-fourteenth of that found in the native enzyme. It is proposed that the presence of catalytic activity in the erythrocyte catalase third molecules may be due to the increased hematin content in the erythrocyte subunit as compared to the liver subunit. Possible implications of the above findings to a hypothetical model of the catalytic action of catalase involving coordinated action of two or more hematins are discussed.