Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of catecholamines and of phenolic drugs. Human platelet PST exists in at least a thermolabile form (TL PST) and a thermostable form (TS PST). The mean basal level of platelet TS PST activity in samples from American blacks is significantly higher than the basal activity in samples from whites. We carried out the studies reported here to determine whether the higher basal TS PST activity in platelet homogenates from blacks was biochemically similar to the lower basal activity in samples from whites. We also characterized variations in TS PST thermal stability. Platelet TS PST activities in samples from the two groups were almost identical with respect to pH optima, Michaelis-Menten constant values for substrates, and susceptibilities to inhibition by 2,6-dichloro-4-nitrophenol and sodium chloride. Thermolabile and thermostable TS PST were present in samples from both blacks and whites. Thermal stabilities of TS PST in samples from 167 volunteers (104 blacks, 63 whites) were expressed as heated sample-to-control sample ratios. Bimodal frequency distribution histograms of the heated-to-control ratios revealed subgroups of samples with thermolabile TS PST activities from 13.5% of blacks (heated-to-control ratio less than 0.32) and 12.7% of whites (heated-to-control ratio less than 0.27). The mean heated-to-control ratio for thermostable TS PST from blacks was significantly higher than that from whites (0.52 +/- 0.01 vs 0.43 +/- 0.01, respectively, mean +/- SEM; p less than 0.0001). Our studies demonstrated the similarity of biochemical properties of platelet TS PST at the extremes of basal activity. They also showed equivalent subgroups of blacks and whites with thermolabile TS PST. The results are an important initial step toward testing the hypothesis that inheritance may be one factor in the regulation of basal levels of activities and thermal stabilities of platelet TS PST from American blacks.
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PMID:Human platelet thermostable phenol sulfotransferase from blacks and whites: biochemical properties and variations in thermal stability. 319 32

Pituitary tissue contains phenol sulfotransferase (PST), the enzyme that catalyzes the sulfate conjugation of monoamine neurotransmitters. We carried out these studies with pituitaries obtained 21.3 +/- 3.0 h postmortem (mean +/- SEM; n = 21) to determine whether the biochemical properties and variations in levels of human pituitary PST activities were similar to those of PST in platelets from control subjects. PST in the human platelet has been studied thoroughly because of the possibility that platelet PST might reflect levels of PST activity in other tissues such as the pituitary and brain. Our results demonstrated 2 forms of the pituitary enzyme that were similar to the thermostable (TS) and thermolabile (TL) forms of platelet PST with regard to assay conditions, pH optima, Km values for multiple substrates, responses to 2,6-dichloro-4-nitrophenol (DCNP), and thermal stability properties. Pituitary samples also were obtained at autopsy 6.3 +/- 0.33 h (mean +/- SEM; n = 3) after death to determine the effects of storage at 4 degrees C on PST activities. After storage for 6-18 h, 83-99.6% of the TS PST activity remained and 44-66.9% of the TL PST activity remained. Pituitary TS PST activity in samples obtained within 12.1 +/- 3.25 h after death was 121.0 +/- 49.1 units/mg protein (mean +/- SEM; n = 7) with a range from 9.7 to 367.6. TL PST activity was 35.6 +/- 11.6 units/mg protein (mean +/- SEM; n = 6) with a range from 6.1 to 80.7. Wide variations of both enzyme activities were also present in 3 pituitary tumor samples.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Human pituitary phenol sulfotransferase: biochemical properties and activities of the thermostable and thermolabile forms. 346 54

To determine whether pheochromocytoma phenol sulfotransferase (PST) activities were similar to blood platelet PST activities, we established assay conditions and biochemical properties for the human pheochromocytoma enzymes. At least two forms of PST were present in high speed supernatant (HSS) preparations of the tumors. A thermolabile form (TL) and a thermostable form (TS) were similar to those of human platelet PST with regard to pH optima, apparent Km values, responses to 2,6-dichloro-4-nitrophenol and thermal stability. PST activities were measured in 74 tumors of neuroectodermal origin that had been stored at -80 degrees C for a mean of 37.9 months. Levels of TL and TS PST activities decreased in a nonlinear fashion with time of sample storage. TL and TS PST activities of 4 samples assayed after 1.08 +/- 1.95 (mean +/- SD) month of storage were 167 +/- 73 and 3,110 +/- 1,817 U/mg protein, respectively (mean +/- SEM). Our results indicated that the TL and TS forms of PST in pheochromocytoma HSS preparations were biochemically similar to platelet PST activities.
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PMID:Human pheochromocytoma phenol sulfotransferase: biochemical properties and activities of thermolabile and thermostable forms. 347 93

Thermolabile (TL) and thermostable (TS) forms of human platelet phenol sulfotransferase (PST) were measured over various periods of time. TL PST was assayed with dopamine as the substrate and TS PST was measured with phenol and with p-nitrophenol. Levels of TL and TS PST from the same subjects did not change significantly over 1 day, 1 week, 4 weeks, and 8.5 months. Interassay coefficients of variation of PST activities over 3-4 weeks measured in samples from 8-12 subjects with dopamine, phenol and p-nitrophenol were 13.96%, 13.60% and 13.30%, respectively. There was a significant correlation between PST activity measured in the same samples with phenol and with p-nitrophenol (r = 0.946, n = 18, p less than 0.0001). TS PST activity measured with p-nitrophenol was significantly higher (p less than 0.0001) in platelets from 51 black subjects than the level of TS PST in samples from 52 white subjects (0.72 +/- 0.06 vs 0.42 +/- 0.04 units/10(8) platelets, respectively; mean +/- SEM). These results demonstrate the 'stability' of the levels of both forms of the enzyme with time. They also point out the usefulness of a reproducible assay for the detection of a racial difference in the levels of TS PST.
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PMID:Human platelet phenol sulfotransferase: stability of two forms of the enzyme with time and presence of a racial difference. 658 30

Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of catecholamines and phenol and catechol drugs. The human blood platelet contains a thermolabile (TL) form of PST that catalyzes the sulfate conjugation of dopamine and other monoamines and a thermostable (TS) form that catalyzes the sulfate conjugation of micromolar concentrations of phenol and p-nitrophenol. Experiments were performed to determine whether the brain contains forms of PST analogous to the TL and TS forms found in the human platelet, and to determine whether there are regional variations in human brain PST activity. We found that the human brain contains at least two forms of PST, forms that are similar to the platelet TS and TL forms of the enzyme with respect to substrate specificity, apparent Km constants, thermal stability, and sensitivity to inhibitors. Optimal conditions were determined for the measurement of these two activities in brain homogenates. The stability of PST activities in the human brain after death was determined in five samples of cerebral cortex that were obtained during clinically indicated neurosurgical procedures. An average of 76 +/- 8% and 80 +/- 9% (mean +/- SEM) of the basal TL and TS PST activities, respectively, remained in these five samples of cerebral cortex after 8 h of storage under simulated post-mortem conditions. Six human brains were then obtained less that 8 h after death from patients who had no neurological disease prior to death. The mean activities of the TL and TS forms of PST were measured in 17 different regions of the six brains. If the pituitary was excluded from consideration, TL and TS PST activities both varied approximately fivefold among these regions, and both activities were highest in cerebral cortex. However, the average TS activity in the anterior pituitary, a tissue of non-neural origin embryologically, was 6.5-fold greater than the highest average TS PST activity found in cerebral cortex.
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PMID:Human brain phenol sulfotransferase: biochemical properties and regional localization. 658 61