Rat phenol sulfotransferase. Assay procedure, developmental changes, and glucocorticoid regulation.
Rat phenol sulfotransferase. Assay procedure, developmental changes, and glucocorticoid regulation.
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大鼠苯酚磺基转移酶。
DOI：
10.1016/0006-2952(82)90473-7
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发表时间：
1982
影响因子：
5.8
通讯作者：
Weinshilboum,RM
中科院分区：
文献类型：
--
作者：
Maus,TP;Pearson,RK;Anderson,RJ;Woodson,LC;Reiter,C;Weinshilboum,RM
苯酚转移酶(PST)催化酚单胺和酚类药物的硫酸盐偶联反应。由于存在强大的内源性PST抑制剂，准确测量组织匀浆中的PST活性一直是很困难的。确定了在极稀组织匀浆中测定大鼠PST的最佳条件。这些情况否定了内源性酶抑制剂的作用。硫酸盐受体底物3-甲氧基-4-羟基苯甘醇对肝、肾和脑匀浆的Km值分别为0.15、0.14和0.02 mm。硫酸盐供体3‘-磷酸腺苷-5’-硫代磷酸在同一组织中的Km值分别为0.11、0.07和0.07μM。从出生到10周，每毫克蛋白表达的大鼠PST活性在肝脏中增加了6.3倍，在大脑中增加了6.6倍，在肾脏中没有变化。地塞米松(每天7μ摩尔/kg，连续3天)治疗后，肾上腺切除大鼠和假手术组大鼠肾脏PST活性均增加5倍。在地塞米松每日治疗72小时内，脑酶活性没有变化，肝脏PST活性仅增加了41%。肾上腺切除组和假手术组三种组织的基础酶活性均无差异。地塞米松对大鼠肾脏PST活性的升高具有剂量依赖性，用蛋白质合成抑制剂放线菌酮处理动物可阻断地塞米松引起的大鼠肾脏PST活性的升高。用地塞米松处理8个近交系和2个近交系大鼠，肾脏PST显著升高，肝脏PST略有升高，而脑酶活性均无明显变化。
Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of phenolic monoamines and phenolic drugs. It has been difficult to measure PST activity in tissue homogenates accurately because of the presence of potent endogenous PST inhibitors. Optimal conditions were determined for the assay of rat PST in very dilute tissue homogenates. These conditions negated the effects of endogenous enzyme inhibitors. ApparentKmvalues for 3-methoxy-4-hydroxyphenylglycol, the sulfate acceptor substrate used, were 0.15, 0.14, and 0.02 mM for liver, kidney, and brain homogenates respectively. ApparentKmvalues in the same tissues for 3'-phosphoadenosine-5'-pnosphosulfate, the sulfate donor, were 0.11, 0.07, and 0.07 μM respectively. Rat PST activity expressed per mg protein increased 6.3-fold in the liver, 6.6-fold in the brain, and did not change in the kidney between birth and 10 weeks of age. There was a 5-fold increase in kidney PST activity in both adrenalectomized and sham-operated Sprague-Dawley rats after treatment with dexamethasone (7 μmoles/kg daily for 3 days). Brain enzyme activity was unchanged and liver PST activity increased only 41% during 72 hr of daily treatment with dexamethasone. Basal enzyme activities in all three tissues were no different in adrenalectomized and sham-operated animals. The increase in rat kidney PST activity in response to dexamethasone was dose dependent, and treatment of animals with cycloheximide, a protein synthesis inhibitor, blocked the elevation of kidney PST activity after dexamethasone. Treatment of eight inbred and two outbred rat strains with dexamethasone resulted in striking increases in renal PST, smaller increases in liver PST, and no changes in brain enzyme activity in all ten strains.