TY - JOUR
T1 - Human intestinal phenol sulfotransferase
T2 - Assay conditions, activity levels and partial purification of the thermolabile form
AU - Sundaram, R. S.
AU - Szumlanski, C.
AU - Otterness, D.
AU - Van Loon, J. A.
AU - Weinshilboum, R. M.
PY - 1989
Y1 - 1989
N2 - Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of catecholamines and phenolic and catechol drugs. The small intestine is an important drug-metabolizing organ. Other human tissues including brain, liver, and platelet contain at least two forms of PST. A thermolabile (TL) form catalyzes the sulfate conjugation of dopamine and other monoamines whereas a thermostable (TS) form of the enzyme catalyzes the sulfate conjugation of 'simple' phenols such as p-nitrophenol. In this study we found that human jejunal mucosa also contains at least two forms of PST with substrate specificities, sensitivities to inhibitors, and thermal stabilities similar to those of TL and TS PST in other human tissues. Optimal conditions were determined for the assay of TL and TS PST activities in jejunal mucosal preparations. Apparent K(m) values of TL PST for dopamine and of TS PST for p-nitrophenol were 10 μM and 0.92 μM, respectively. Jejunal mucosal TL PST, like TL PST in other human tissues, also catalyzed the sulfation of p-nitrophenol, but with a very high apparent K(m) of 1100 μM. PST activities were then assayed in 64 samples of jejunum obtained surgically, and average activities for TL and TS PST were 102 ± 4.6 and 47.4 ± 2.9 units per milligram of protein, (mean ± SE), with 40 μM dopamine and 2 μM p-nitrophenol as substrates, respectively. Since jejunal mucosal TL PST had a much higher specific activity than that present in other human tissues, TL PST was partially purified from jejunal mucosa by ion exchange and Affi-Gel Blue chromatography. The substrate specificity, inhibitor sensitivity, and physical properties of partially purified jejunal TL PST were similar to those of TL PST in supernatants of jejunal mucosal homogenates. True K(m) values of the partially purified enzyme for dopamine and p-nitrophenol were 6.7 μM and 1400 μM, respectively. Human jejunal TL PST had an apparent molecular mass of 69 kDa with 35.5-kDa monomers. In summary, human jejunal mucosa contains forms of PST similar to those found in other human tissues, and human jejunal mucosa is a good source for the purification of TL PST.
AB - Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of catecholamines and phenolic and catechol drugs. The small intestine is an important drug-metabolizing organ. Other human tissues including brain, liver, and platelet contain at least two forms of PST. A thermolabile (TL) form catalyzes the sulfate conjugation of dopamine and other monoamines whereas a thermostable (TS) form of the enzyme catalyzes the sulfate conjugation of 'simple' phenols such as p-nitrophenol. In this study we found that human jejunal mucosa also contains at least two forms of PST with substrate specificities, sensitivities to inhibitors, and thermal stabilities similar to those of TL and TS PST in other human tissues. Optimal conditions were determined for the assay of TL and TS PST activities in jejunal mucosal preparations. Apparent K(m) values of TL PST for dopamine and of TS PST for p-nitrophenol were 10 μM and 0.92 μM, respectively. Jejunal mucosal TL PST, like TL PST in other human tissues, also catalyzed the sulfation of p-nitrophenol, but with a very high apparent K(m) of 1100 μM. PST activities were then assayed in 64 samples of jejunum obtained surgically, and average activities for TL and TS PST were 102 ± 4.6 and 47.4 ± 2.9 units per milligram of protein, (mean ± SE), with 40 μM dopamine and 2 μM p-nitrophenol as substrates, respectively. Since jejunal mucosal TL PST had a much higher specific activity than that present in other human tissues, TL PST was partially purified from jejunal mucosa by ion exchange and Affi-Gel Blue chromatography. The substrate specificity, inhibitor sensitivity, and physical properties of partially purified jejunal TL PST were similar to those of TL PST in supernatants of jejunal mucosal homogenates. True K(m) values of the partially purified enzyme for dopamine and p-nitrophenol were 6.7 μM and 1400 μM, respectively. Human jejunal TL PST had an apparent molecular mass of 69 kDa with 35.5-kDa monomers. In summary, human jejunal mucosa contains forms of PST similar to those found in other human tissues, and human jejunal mucosa is a good source for the purification of TL PST.
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M3 - Article
C2 - 2568905
AN - SCOPUS:0024309210
SN - 0090-9556
VL - 17
SP - 255
EP - 264
JO - Drug Metabolism and Disposition
JF - Drug Metabolism and Disposition
IS - 3
ER -