Biosynthesis of uniformly labeled 13C- and 14C-arachidonic acid in Mortierella alpina

Abstract Arachidonic acid (ARA) is one of the most abundant polyunsaturated fatty acids (PUFAs) in the mammalian brain. Many enzymatically- and nonenzymatically-produced metabolic products have important and potent pharmacological properties. However, uniformly isotope labeled forms of ARA are not commercially available for studying the metabolic fates of ARA. This study describes a simple and efficient protocol for the biosynthesis of U- 13 C-ARA from U- 13 C-glucose, and U- 14 C-ARA from U- 14 C-glucose by Mortierella alpina . The protocols yield approximately 100 nmol quantities of U- 13 C-ARA with an isotopic purity of 95% from a 500 μl batch volume, and approximately 2 μCi quantities of U- 14 C-ARA with an apparent specific activity in excess of 1200 Ci/mol from a 250 μl batch volume.