TY - JOUR
T1 - Phenolsulphotransferase in human tissue
T2 - Radiochemical enzymatic assay and biochemical properties
AU - Anderson, R. J.
AU - Weinshilboum, R. M.
N1 - Funding Information:
We thank Luanne Wussow, Joel Dunnette, and Robert J. Johnson for their assistance with these studies. This work was supported in part by NIH Grants NS 11014, HL 17487, and HL 07269.
PY - 1980/4/11
Y1 - 1980/4/11
N2 - Phenolsulphotransferase (EC 2.8.2.1) (PST) is an important catecholamine and drug metabolizing enzyme. Optimal conditions have been determined for the accurate measurement of PST activity in the human platelet, human renal cortex, and human jejunum with a radiochemical microassay. 3-Methoxy-4-hydroxyphenylglycol (MHPG) and 35S-3'-phosphoadenosine-5'-phosphosulfate (35S-PAPS) were the substrates for the reaction. The apparent Michaelis-Menten (Km) values for MHPG with platelet, renal cortex, and jejunum were 1.09, 0.46 and 1.16 mmol/l, respectively. Apparent Km values for PAPS in the same tissues were 0.14, 0.13 and 0.21 μmol/l. The pH optimum of the reaction in all three tissues was approximately 6.2-6.8 with three different buffer systems. The coefficients of variation for the assay of platelet, renal cortex, and jejunal activities were 6.2%, 3.4% and 4.4%, respectively. Mean platelet PST activity in blood samples from 75 randomly selected adult subjects was 5.0 ± 1.72 nmol of MHPG sulfate formed per hour per mg of platelet protein (8.3 × 10-5 ± 2.9 × 10-5μmol · min-1 · mg-1, mean ± S.D.). There was a 5-fold intersubject variation in platelet PST activity within two standard deviations of the mean value. Experiments in which partially purified human erythrocyte PST was added to platelet, kidney and gut homogenates under these assay conditions provided evidence that endogenous PST inhibitors did not affect the observed enzyme activity.
AB - Phenolsulphotransferase (EC 2.8.2.1) (PST) is an important catecholamine and drug metabolizing enzyme. Optimal conditions have been determined for the accurate measurement of PST activity in the human platelet, human renal cortex, and human jejunum with a radiochemical microassay. 3-Methoxy-4-hydroxyphenylglycol (MHPG) and 35S-3'-phosphoadenosine-5'-phosphosulfate (35S-PAPS) were the substrates for the reaction. The apparent Michaelis-Menten (Km) values for MHPG with platelet, renal cortex, and jejunum were 1.09, 0.46 and 1.16 mmol/l, respectively. Apparent Km values for PAPS in the same tissues were 0.14, 0.13 and 0.21 μmol/l. The pH optimum of the reaction in all three tissues was approximately 6.2-6.8 with three different buffer systems. The coefficients of variation for the assay of platelet, renal cortex, and jejunal activities were 6.2%, 3.4% and 4.4%, respectively. Mean platelet PST activity in blood samples from 75 randomly selected adult subjects was 5.0 ± 1.72 nmol of MHPG sulfate formed per hour per mg of platelet protein (8.3 × 10-5 ± 2.9 × 10-5μmol · min-1 · mg-1, mean ± S.D.). There was a 5-fold intersubject variation in platelet PST activity within two standard deviations of the mean value. Experiments in which partially purified human erythrocyte PST was added to platelet, kidney and gut homogenates under these assay conditions provided evidence that endogenous PST inhibitors did not affect the observed enzyme activity.
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U2 - 10.1016/0009-8981(80)90233-8
DO - 10.1016/0009-8981(80)90233-8
M3 - Article
C2 - 6930336
AN - SCOPUS:0018835352
SN - 0009-8981
VL - 103
SP - 79
EP - 90
JO - Clinica Chimica Acta
JF - Clinica Chimica Acta
IS - 1
ER -