Abstract
In our attempts to increase intracellular tetrahydrobiopterin (BH4) concentration, we found that direct administration of BH4 is inefficient and that sepiapterin is taken up more efficiently by cells and converted to BH4 (1). While exploring the mechanism of BH4-uptake using cultured animal cells, we found that cells take up BH4 rapidly but quickly release the incorporated pterin (2). The mechanism and physiological significance of this is not known. In this study, we refined the time course of the experiment down to a matter of seconds to make the results more reproducible and the determination of BH4 was performed more carefully, keeping in mind its redox state, according to the method of Fukushima and Nixon (3). We compared the process with sepiapterin uptake and found that the cells take up BH4 from the medium and oxidize it to dihydro-biopterin which is preferentially released from the cells. Thus the accumulation of BH4 was very slow and inefficient due to its oxidation.
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References
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Hasegawa, H. et al. (2002). Cells Take up BH4, Oxidize It and the Oxidized Biopterin is Preferentially Released. In: Milstien, S., Kapatos, G., Levine, R.A., Shane, B. (eds) Chemistry and Biology of Pteridines and Folates. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-0945-5_34
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DOI: https://doi.org/10.1007/978-1-4615-0945-5_34
Publisher Name: Springer, Boston, MA
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