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

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-13C-ARA from U-13C-glucose, and U-14C-ARA from U-14C-glucose by Mortierella alpina. The protocols yield approximately 100nmol quantities of U-13C-ARA with an isotopic purity of 95% from a 500μl batch volume, and approximately 2μCi quantities of U-14C-ARA with an apparent specific activity in excess of 1200Ci/mol from a 250μl batch volume.