The enzymatic basis for the rat liver 6-hydroxymelatonin sulfotransferase activity.

Abstract

Understanding 6-hydroxymelatonin (6HM) sulfation is deemed important to explaining normal and oncostatic actions of the pineal gland. Here we identify the enzymatic basis for this sulfation in rats. First, a quantitative assay was designed for measuring hepatic 6HM sulfotransferase (6HMST) activity. The assay was then used to identify a male dominant sexual dimorphism wherein liver from males contains double the 6HMST per g or per 100 g body weight seen in females. Examination of other rat tissues showed that most in vivo 6HM sulfation was likely to occur in liver. In addition, DEAE-Sephadex chromatography of liver cytosol indicated that 80-90% of the 6HMST activity in both sexes was due to an enzyme we named 6HMST II. A minor 6HM sulfotransferase (6HMST I) eluted from the columns prior to the main enzyme. 6HMST II, purified additionally, was shown to convert 6HM to a product that appeared to be 6HM sulfate (6-sulfa-toxymelatonin). The enzyme was inhibited by Na+, K+, Zn2+, and Cd2+. Its pH optimum was 7.80 +/- 0.30. Comparisons are made between 6HMST II, dopamine sulfotransferase II, and aryl sulfotransferase IV.

• Authors: S S Singer, J E Hagedorn, D M Smith, J L Williams
• Journal: Journal of pineal research (J Pineal Res) Vol. 18 Issue 1 Pg. 49-55 (Jan 1995) ISSN: 0742-3098 [Print] England
• PMID: 7776179 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Enzyme Inhibitors
• 6-hydroxymelatonin sulfotransferase
• Sulfotransferases
• Arylsulfotransferase
• Melatonin
• 6-hydroxymelatonin

Topics

• Animals
• Arylsulfotransferase (metabolism)
• Chromatography, Gel
• Chromatography, Ion Exchange
• Cytosol (enzymology)
• Enzyme Inhibitors
• Enzyme Stability
• Female
• Hydrogen-Ion Concentration
• Liver (enzymology)
• Male
• Melatonin (analogs & derivatives, metabolism)
• Rats
• Rats, Sprague-Dawley
• Sex Characteristics
• Sulfotransferases (chemistry, isolation & purification, metabolism)