Tetrahydro‐6‐biopterin is associated with tetrahydro‐7‐biopterin in primary murine mast cells

Abstract
Murine bone marrow-derived mast cells proliferate in response to interleukin 3. In addition to 6-biopterin, 7-biopterin was identified in these cells by HPLC analysis of iodine oxidized extracts and by alkaline permanganate oxidation to the 6- and 7-carboxylic acids. 7-Biopterin comprised 31.9 (± 7.7)% of the total biopterin. It was absent in cells which were grown with of l-p-chlorophenylalanine, an inhibitor of tryptophan 5-monooxygenase. Both 6- and 7-biopterin were present in the cell as their tetrahydro forms. From these data we conclude that 7-biopterin, in contrast to e.g. brain tissue, regularly occurs as a normal metabolite in primary mast cells and that it is generated during hydroxylation of tryptophan.