Quebec E A, Chang T M
Artificial Cells and Organs Research Centre, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
Artif Cells Blood Substit Immobil Biotechnol. 1995;23(6):693-705. doi: 10.3109/10731199509117981.
Superoxide dismutase (SOD) and catalase (CAT) were evaluated for their ability to reduce methemoglobin formation in chemically cross-linked hemoglobin that was incubated in Tris-HCl buffer. Two parallel studies were carried out using identical experimental conditions with one exception only. This involved the physical state of SOD and CAT in solution such that the enzymes were either cross-linked directly to hemoglobin (hemoglobin-SOD-CAT) or simply incubated with polyhemoglobin. The concentration of SOD and CAT was subsequently varied to examine and compare the effect on the rate of methemoglobin formation between the two experiments. Overall, a comparison between the results clearly indicated that cross-linking SOD and CAT to hemoglobin was more effective at reducing methemoglobin levels than incubating polyhemoglobin with SOD and CAT. More specifically, the incubation experiment would require an enzyme concentration exceeding twice that cross-linked to hemoglobin in order to achieve a similar beneficial effect. However, it was more striking to observe that the presence of SOD and CAT during the cross-linking reaction had markedly reduced the initial formation of methemoglobin. When SOD and CAT were included during the chemical process of generating polyhemoglobin, about 7% methemoglobin was formed in the cross-linked hemoglobin-SOD-CAT product. By comparison, methemoglobin had increased about 20% after the cross-linking reaction when generating polyhemoglobin.
在Tris-HCl缓冲液中孵育的化学交联血红蛋白中，评估了超氧化物歧化酶（SOD）和过氧化氢酶（CAT）减少高铁血红蛋白形成的能力。进行了两项平行研究，采用相同的实验条件，仅一个例外。这涉及溶液中SOD和CAT的物理状态，使得酶要么直接交联到血红蛋白上（血红蛋白-SOD-CAT），要么简单地与多聚血红蛋白一起孵育。随后改变SOD和CAT的浓度，以检查和比较两个实验中对高铁血红蛋白形成速率的影响。总体而言，结果之间的比较清楚地表明，将SOD和CAT交联到血红蛋白上在降低高铁血红蛋白水平方面比将多聚血红蛋白与SOD和CAT一起孵育更有效。更具体地说，孵育实验需要的酶浓度超过交联到血红蛋白上的酶浓度的两倍，才能达到类似的有益效果。然而，更引人注目的是观察到在交联反应过程中SOD和CAT的存在显著降低了高铁血红蛋白的初始形成。当在生成多聚血红蛋白的化学过程中加入SOD和CAT时，交联的血红蛋白-SOD-CAT产物中形成了约7%的高铁血红蛋白。相比之下，在生成多聚血红蛋白的交联反应后，高铁血红蛋白增加了约20%。
