Abstract
The substrate specificity of the thermostable phenol sulfotransferase (PST) from primary cultures of brain microvessel endothelial cell monolayers was characterized. Selected catecholamines, catecholamine metabolites, and p-nitrophenol at 5, 50, and 500 μM were used as substrates in PST assays of cytosol extracts. Endogenous catecholamines, epinephrine, norepinephrine, and dopamine, exhibited no detectable activity as substrates (500 μM) compared to 500 μM p-nitrophenol as substrate (1.8 pmol/mg/min specific activity) for the PST. In contrast, 500 μM of either deaminated or 3-O-methylated metabolites of catecholamines exhibited intermediate (≈1.0 pmol/mg/min specific activity) to low (≈0.2 pmol/mg/min specific activity) activity, respectively, as substrates compared to p-nitrophenol as substrate for the PST. Additionally, 500 μM of metabolites of catecholamines that were both deaminated and 3-0-methylated exhibited high activity (>3.0 pmol/mg/min specific activity) as substrates compared top-nitrophenol as substrate for the PST. Qualitatively similar results were observed at lower substrate concentrations. Therefore, results from this study suggest a potential role for PST as part of the “enzymatic” blood-brain barrier in regulating transendothelial passage of endogenous catecholamines between the blood and the brain.
Similar content being viewed by others
References
Weinshilboum, R. M. 1986. Phenol sulfotransferase in humans: Properties, regulation and function. Fed. Proc. 45:2223–2228.
Young, W. F. Jr., Okazaki, H., Laws, E. R., Jr., and Weinshilboum, R. M. 1984. Human brain phenol sulfotransferase: biochemical properties and regional localization. J. Neurochem. 43:706–715.
Baranczyk-Kuzma, A., Audus, K. L., and Borchardt, R. T. 1986. Catecholamine-metabolizing enzymes of bovine brain microvessel endothelial cell monolayers. J. Neurochem. 46:1956–1960.
Baranczyk-Kuzma, A., Borchardt, R. T., Schasteen, C. S., and Pinnick, C. L. 1981. Pages 55–73,in Sandler, M. and Usdin, E. (eds.), Phenol-Sulfotransferase in Mental Health Research, MacMillan Co., New York.
Audus, K. L. and Borchardt, R. T. 1987. Bovine brain microvessel endothelial cell monolayers as a model system for the bloodbrain barrier. Ann. N. Y. Acad. Sci. 507:9–18.
Audus, K. L. and Borchardt, R. T. 1986. Characterization of an in vitro blood-brain barrier model system for studying drug transport and metabolism. Pharm. Res. 3:81–87.
Foldes, A. and Meek, J. L. 1973. Rat brain phenol sulfotransferase-partial purification and some properties. Biochim. Biophys. Acta 327:365–374.
Lowry, O. H., Rosebrough, N. J., Farr, A. L., and Randall, R. J. 1951. Protein measurement with the Folin phenol reagent. J. Biol. Chem. 193:265–274.
Campbell, N. R. C., Van Loon, J. A., and Wenshilboum, R. M., 1987. Human liver phenol sulfotransferase: Assay conditions, biochemical properties and partial purification of isozymes of the thermostable form. Biochem. Pharmacol. 36:1435–1446.
Campbell, N. R. C., Van Loon, J. A., Sundaram, R. S., Ames, M. M., Hansch, C., and Weinshilboum, R. 1988. Human and rat liver phenol sulfotransferase: Structure-activity relationships for phenolic substrates. Mol. Pharmacol. 32:813–819.
Ghersi-Egea, J.-F., Minn, A., and Siest, G. 1988. A new aspect of the protective functions of the blood-brain barrier: Activities of four drug-metabolizing enzymes in isolated rat brain microvessels. Life Sci. 42:2525–2533.
Joo, F. 1985. The blood-brain barrier in vitro: ten years of research on microvessels isolated from the brain. Neurochem. Int. 7:1–25.
Roth, J. A. and Rivett, A. J. 1982. Does sulfate conjugation contribute to the metabolic inactivation of catecholamines in humans? Biochem. Pharmacol. 31:3017–3018.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Baranczyk-Kuzma, A., Audus, K.L. & Borchardt, R.T. Substrate specificity of phenol sulfotransferase from primary cultures of bovine brain microvessel endothelium. Neurochem Res 14, 689–691 (1989). https://doi.org/10.1007/BF00964880
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00964880