p1. Two enzymes (A and B) which catalyse the sulphation of ip/i-nitrophenol and l-tyrosine methyl ester have been isolated from female rat livers. One of these enzymes (A) also catalyses the sulphation of dehydroepiandrosterone. 2. The iKsubm/sub/i values for the sulphation of ip/i-nitrophenol and l-tyrosine methyl ester by enzyme B at pH7.5 are 1.5μm and 2.9mm respectively. 3. Enzyme B is oxidized on keeping at 0°C when the iKsubm/sub/i and iV/isubmax./sub values for the sulphation of ip/i-nitrophenol are increased approx. 200-fold and fourfold respectively. This oxidized preparation of enzyme B fails to catalyse the sulphation of l-tyrosine methyl ester. 4. When the oxidized form of enzyme B is kept at 0°C and low ionic strength then further forms of ip/i-nitrophenol sulphotransferase are produced having even lower affinities for the sulphate acceptor. 5. The iKsubm/sub/i value for adenosine 3′-phosphate 5′[sup35/supS]-sulphatophosphate is not affected during storage of the enzyme under these conditions. 6. Prolonged storage of enzyme B at low ionic strength leads to a considerable degree of polymerization of ip/i-nitrophenol sulphotransferase and l-tyrosine methyl ester sulphotransferase. 7. The changes in the kinetic properties and molecular size of enzyme B during storage are reversed by dithiothreitol./p
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机译：> 1。从雌性大鼠肝脏中分离出了两种催化 p-硝基苯酚和1-酪氨酸甲酯硫酸化的酶（A和B）。这些酶之一（A）也催化脱氢表雄酮的硫酸化。 2.在pH7.5的条件下，酶B硫酸化 p -硝基苯酚和1-酪氨酸甲酯的 K m 值为1.5μm和2.9mm。 3.当 K m 和 V max。的值保持在0°C时，酶B被氧化对-硝基苯酚的硫酸化增加。分别是200倍和4倍。酶B的这种氧化的制备物不能催化1-酪氨酸甲酯的硫酸化。 4.当酶B的氧化形式保持在0℃且离子强度低时，会产生对硫酸盐受体具有甚至更低亲和力的其他形式的对硝基硝基苯酚磺基转移酶。 5.腺苷3'-磷酸5'[ 35 S]-硫酸磷酸的 K m 值在以下条件下储存酶时不受影响这些条件。 6.在低离子强度下长时间储存酶B导致p-硝基苯酚磺基转移酶和1-酪氨酸甲酯磺酸基转移酶的相当程度的聚合。 7.二硫苏糖醇逆转了酶B的动力学特性和分子大小的变化。
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