Nadruz W, Marques E T, Azevedo W M, Lima-Filho J L, Carvalho L B
Departamento de Bioquímica, Universidade Federal de Pernambuco, Recife, PE Brasil.
Braz J Med Biol Res. 1996 Mar;29(3):347-50.
A polyaniline silicone support to immobilize xanthine oxidase is proposed as a reactor coil to monitor the action of xanthine oxidase on hypoxanthine, xanthine and 6-mercaptopurine. A purified xanthine oxidase immobilized on this support lost 80% of the initial activity after 12 min of use. Co-immobilization of superoxide dismutase and catalase increased the stability of immobilized xanthine oxidase so that the derivative maintained 79% of its initial activity after 4.6 h of continuous use in which 1.5 mumol purine bases were converted by the immobilized enzyme system. There is no evidence of either polyaniline or protein leaching from the coil during 3 h of continuous use. When solutions (10 ml) of hypoxanthine, xanthine and 6-mercaptopurine were circulated individually through the xanthine oxidase-superoxide dismutase-catalase-polyaniline coil (1 mm internal diameter and 3 m in length, 3 ml internal volume) activities of 8.12, 11.17 and 1.09 nmol min-1 coil-1, respectively, were obtained. The advantages of the reactor configuration and the redox properties of the polymer, particularly with respect to immobilized oxidoreductases, make this methodology attractive for similar enzyme systems. This immobilized enzyme system using polyaniline-silicone as support converted 6-mercaptopurine to 6-thiouric acid with equal efficiency as resins based on polyacrylamide and polyamide 11.
一种用于固定黄嘌呤氧化酶的聚苯胺硅氧烷载体被提议作为一种反应线圈，用于监测黄嘌呤氧化酶对次黄嘌呤、黄嘌呤和6-巯基嘌呤的作用。固定在该载体上的纯化黄嘌呤氧化酶在使用12分钟后丧失了80%的初始活性。超氧化物歧化酶和过氧化氢酶的共固定增加了固定化黄嘌呤氧化酶的稳定性，使得该衍生物在连续使用4.6小时后仍保持其初始活性的79%，在此期间固定化酶系统转化了1.5 μmol嘌呤碱。在连续使用3小时的过程中，没有证据表明聚苯胺或蛋白质从线圈中浸出。当次黄嘌呤、黄嘌呤和6-巯基嘌呤的溶液（10 ml）分别通过黄嘌呤氧化酶-超氧化物歧化酶-过氧化氢酶-聚苯胺线圈（内径1 mm，长度3 m，内部体积3 ml）循环时，分别获得了8.12、11.17和1.09 nmol min-1线圈-1的活性。该反应线圈配置的优点以及聚合物的氧化还原性质，特别是对于固定化氧化还原酶而言，使得该方法对类似的酶系统具有吸引力。这种以聚苯胺-硅氧烷为载体的固定化酶系统将6-巯基嘌呤转化为6-硫代尿酸的效率与基于聚丙烯酰胺和聚酰胺11的树脂相当。
