Human liver arylamine N-sulfotransferase activity. Thermostable phenol sulfotransferase catalyzes the N-sulfation of 2-naphthylamine

J. S. Hernandez, S. P. Powers, Richard M Weinshilboum

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Our experiments were performed to determine whether human liver, like that of other mammals, could catalyze the N-sulfation of an arylamine, 2-naphthylamine (2-NA) and, if so, whether this reaction might be catalyzed by one or both of the two known forms of human phenol sulfotransferase (PST). One form of PST is thermostable (TS) and catalyzes the sulfation of ''simple'' phenols such as p-nitro-phenol, while the other form is thermolabile (TL) and catalyzes the sulfate conjugation of phenolic monoamines such as dopamine. When 2-NA that was not contaminated with 2-naphthol was used as substrate, human hepatic cytosol could catalyze the N-sulfation of 2-NA with an apparent K(m) of 322 μM. However, substrate kinetics of the sulfate donor for the reaction, 3'-phosphoadenosine-5'-phosphosulfate, were biphasic, with estimated apparent K(m) values of 0.13 and 2.2 μM for high and low affinity activities, respectively. Human liver arylamine N-sulfotransferase (AANST) activity was similar to that of TS but not TL PST with regard to thermal stability, inhibition by 2,6-dichloro-4-nitrophenol (DCNP), and regulation among individuals. For example, average temperatures that produced 50% inactivation of TL PST, TS PST, and AANST activities, measured with both 0.05 and 1.0 mM 2-NA as substrate, were 35.0, 40.5, 40.3 and 40.5°C, respectively. IC 50 values for the inhibition by DCNP of TL PST, TS PST, and AANST, measured with 0.05 and 1.0 mM 2-NA as substrate, were 110, 1.8, 1.3, and 4.0 μM, respectively. In addition, in cytosolic preparations from 20 individual human liver samples, there was a highly significant correlation between TS PST activity and AANST activity measured with both 0.05 mM 2-NA and 1.0 mM 2-NA as substrate (r(s) = 0.899, p < 0.0001 and r(s) = 0.934, p < 0.0001, respectively). However, there was not a significant correlation between TL PST activity and AANST measured with 0.05 mM and 1.0 mM 2-NA as substrate (r(s) = 0.257, p = 0.278 and r(s) = 0.268, p = 0.258, respectively). Finally, partially purified TS PST, but not partially purified TL PST, catalyzed the N-sulfation of 2-NA. However, substrate kinetic studies once again indicated that the partially purified TS PST preparation might contain two AANST activities. In summary, our results were compatible with the conclusion that TS PST was the major enzyme responsible for catalyzing the N-sulfation of 2-NA in human liver cytosol. However, sulfotransferase(s) other than TS PST might also play a role in this reaction.

Original languageEnglish (US)
Pages (from-to)1071-1079
Number of pages9
JournalDrug Metabolism and Disposition
Volume19
Issue number6
StatePublished - 1991

Fingerprint

Arylsulfotransferase
2-Naphthylamine
Sulfotransferases
Liver
Substrates
amine sulfotransferase
Cytosol
Sulfates
Phosphoadenosine Phosphosulfate
Kinetics
Mammals
Phenols

ASJC Scopus subject areas

  • Pharmacology
  • Toxicology

Cite this

Human liver arylamine N-sulfotransferase activity. Thermostable phenol sulfotransferase catalyzes the N-sulfation of 2-naphthylamine. / Hernandez, J. S.; Powers, S. P.; Weinshilboum, Richard M.

In: Drug Metabolism and Disposition, Vol. 19, No. 6, 1991, p. 1071-1079.

Research output: Contribution to journalArticle

@article{852265b518764d9282e826aeab6206b3,
title = "Human liver arylamine N-sulfotransferase activity. Thermostable phenol sulfotransferase catalyzes the N-sulfation of 2-naphthylamine",
abstract = "Our experiments were performed to determine whether human liver, like that of other mammals, could catalyze the N-sulfation of an arylamine, 2-naphthylamine (2-NA) and, if so, whether this reaction might be catalyzed by one or both of the two known forms of human phenol sulfotransferase (PST). One form of PST is thermostable (TS) and catalyzes the sulfation of ''simple'' phenols such as p-nitro-phenol, while the other form is thermolabile (TL) and catalyzes the sulfate conjugation of phenolic monoamines such as dopamine. When 2-NA that was not contaminated with 2-naphthol was used as substrate, human hepatic cytosol could catalyze the N-sulfation of 2-NA with an apparent K(m) of 322 μM. However, substrate kinetics of the sulfate donor for the reaction, 3'-phosphoadenosine-5'-phosphosulfate, were biphasic, with estimated apparent K(m) values of 0.13 and 2.2 μM for high and low affinity activities, respectively. Human liver arylamine N-sulfotransferase (AANST) activity was similar to that of TS but not TL PST with regard to thermal stability, inhibition by 2,6-dichloro-4-nitrophenol (DCNP), and regulation among individuals. For example, average temperatures that produced 50{\%} inactivation of TL PST, TS PST, and AANST activities, measured with both 0.05 and 1.0 mM 2-NA as substrate, were 35.0, 40.5, 40.3 and 40.5°C, respectively. IC 50 values for the inhibition by DCNP of TL PST, TS PST, and AANST, measured with 0.05 and 1.0 mM 2-NA as substrate, were 110, 1.8, 1.3, and 4.0 μM, respectively. In addition, in cytosolic preparations from 20 individual human liver samples, there was a highly significant correlation between TS PST activity and AANST activity measured with both 0.05 mM 2-NA and 1.0 mM 2-NA as substrate (r(s) = 0.899, p < 0.0001 and r(s) = 0.934, p < 0.0001, respectively). However, there was not a significant correlation between TL PST activity and AANST measured with 0.05 mM and 1.0 mM 2-NA as substrate (r(s) = 0.257, p = 0.278 and r(s) = 0.268, p = 0.258, respectively). Finally, partially purified TS PST, but not partially purified TL PST, catalyzed the N-sulfation of 2-NA. However, substrate kinetic studies once again indicated that the partially purified TS PST preparation might contain two AANST activities. In summary, our results were compatible with the conclusion that TS PST was the major enzyme responsible for catalyzing the N-sulfation of 2-NA in human liver cytosol. However, sulfotransferase(s) other than TS PST might also play a role in this reaction.",
author = "Hernandez, {J. S.} and Powers, {S. P.} and Weinshilboum, {Richard M}",
year = "1991",
language = "English (US)",
volume = "19",
pages = "1071--1079",
journal = "Drug Metabolism and Disposition",
issn = "0090-9556",
publisher = "American Society for Pharmacology and Experimental Therapeutics",
number = "6",

}

TY - JOUR

T1 - Human liver arylamine N-sulfotransferase activity. Thermostable phenol sulfotransferase catalyzes the N-sulfation of 2-naphthylamine

AU - Hernandez, J. S.

AU - Powers, S. P.

AU - Weinshilboum, Richard M

PY - 1991

Y1 - 1991

N2 - Our experiments were performed to determine whether human liver, like that of other mammals, could catalyze the N-sulfation of an arylamine, 2-naphthylamine (2-NA) and, if so, whether this reaction might be catalyzed by one or both of the two known forms of human phenol sulfotransferase (PST). One form of PST is thermostable (TS) and catalyzes the sulfation of ''simple'' phenols such as p-nitro-phenol, while the other form is thermolabile (TL) and catalyzes the sulfate conjugation of phenolic monoamines such as dopamine. When 2-NA that was not contaminated with 2-naphthol was used as substrate, human hepatic cytosol could catalyze the N-sulfation of 2-NA with an apparent K(m) of 322 μM. However, substrate kinetics of the sulfate donor for the reaction, 3'-phosphoadenosine-5'-phosphosulfate, were biphasic, with estimated apparent K(m) values of 0.13 and 2.2 μM for high and low affinity activities, respectively. Human liver arylamine N-sulfotransferase (AANST) activity was similar to that of TS but not TL PST with regard to thermal stability, inhibition by 2,6-dichloro-4-nitrophenol (DCNP), and regulation among individuals. For example, average temperatures that produced 50% inactivation of TL PST, TS PST, and AANST activities, measured with both 0.05 and 1.0 mM 2-NA as substrate, were 35.0, 40.5, 40.3 and 40.5°C, respectively. IC 50 values for the inhibition by DCNP of TL PST, TS PST, and AANST, measured with 0.05 and 1.0 mM 2-NA as substrate, were 110, 1.8, 1.3, and 4.0 μM, respectively. In addition, in cytosolic preparations from 20 individual human liver samples, there was a highly significant correlation between TS PST activity and AANST activity measured with both 0.05 mM 2-NA and 1.0 mM 2-NA as substrate (r(s) = 0.899, p < 0.0001 and r(s) = 0.934, p < 0.0001, respectively). However, there was not a significant correlation between TL PST activity and AANST measured with 0.05 mM and 1.0 mM 2-NA as substrate (r(s) = 0.257, p = 0.278 and r(s) = 0.268, p = 0.258, respectively). Finally, partially purified TS PST, but not partially purified TL PST, catalyzed the N-sulfation of 2-NA. However, substrate kinetic studies once again indicated that the partially purified TS PST preparation might contain two AANST activities. In summary, our results were compatible with the conclusion that TS PST was the major enzyme responsible for catalyzing the N-sulfation of 2-NA in human liver cytosol. However, sulfotransferase(s) other than TS PST might also play a role in this reaction.

AB - Our experiments were performed to determine whether human liver, like that of other mammals, could catalyze the N-sulfation of an arylamine, 2-naphthylamine (2-NA) and, if so, whether this reaction might be catalyzed by one or both of the two known forms of human phenol sulfotransferase (PST). One form of PST is thermostable (TS) and catalyzes the sulfation of ''simple'' phenols such as p-nitro-phenol, while the other form is thermolabile (TL) and catalyzes the sulfate conjugation of phenolic monoamines such as dopamine. When 2-NA that was not contaminated with 2-naphthol was used as substrate, human hepatic cytosol could catalyze the N-sulfation of 2-NA with an apparent K(m) of 322 μM. However, substrate kinetics of the sulfate donor for the reaction, 3'-phosphoadenosine-5'-phosphosulfate, were biphasic, with estimated apparent K(m) values of 0.13 and 2.2 μM for high and low affinity activities, respectively. Human liver arylamine N-sulfotransferase (AANST) activity was similar to that of TS but not TL PST with regard to thermal stability, inhibition by 2,6-dichloro-4-nitrophenol (DCNP), and regulation among individuals. For example, average temperatures that produced 50% inactivation of TL PST, TS PST, and AANST activities, measured with both 0.05 and 1.0 mM 2-NA as substrate, were 35.0, 40.5, 40.3 and 40.5°C, respectively. IC 50 values for the inhibition by DCNP of TL PST, TS PST, and AANST, measured with 0.05 and 1.0 mM 2-NA as substrate, were 110, 1.8, 1.3, and 4.0 μM, respectively. In addition, in cytosolic preparations from 20 individual human liver samples, there was a highly significant correlation between TS PST activity and AANST activity measured with both 0.05 mM 2-NA and 1.0 mM 2-NA as substrate (r(s) = 0.899, p < 0.0001 and r(s) = 0.934, p < 0.0001, respectively). However, there was not a significant correlation between TL PST activity and AANST measured with 0.05 mM and 1.0 mM 2-NA as substrate (r(s) = 0.257, p = 0.278 and r(s) = 0.268, p = 0.258, respectively). Finally, partially purified TS PST, but not partially purified TL PST, catalyzed the N-sulfation of 2-NA. However, substrate kinetic studies once again indicated that the partially purified TS PST preparation might contain two AANST activities. In summary, our results were compatible with the conclusion that TS PST was the major enzyme responsible for catalyzing the N-sulfation of 2-NA in human liver cytosol. However, sulfotransferase(s) other than TS PST might also play a role in this reaction.

UR - http://www.scopus.com/inward/record.url?scp=0025747916&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025747916&partnerID=8YFLogxK

M3 - Article

C2 - 1687013

AN - SCOPUS:0025747916

VL - 19

SP - 1071

EP - 1079

JO - Drug Metabolism and Disposition

JF - Drug Metabolism and Disposition

SN - 0090-9556

IS - 6

ER -