A new synthesis of [3-11C]pyruvic acid using alanine racemase

The synthesis of [3-11C]pyruvic acid was attempted by two reaction systems (A: alanine racemase and image-amino acid oxidase, B: alanine racemase and image-alanine dehydrogenase) utilizing a new thermostable enzyme, alanine racemase. Conversion rates from image,image-[3-11C]alanine to [3-11C]pyruvic acid were almost 100% in both methods. Similar results were obtained with immobilized enzymes packed in a single column. Furthermore, the same column could be used repeatedly without a remarkable decrease of the [3-11C]pyruvic acid yield. Various matrices were tested for the immobilizing enzyme, and Aminopropyl-CPG was concluded to be the most suitable since the loss of the enzyme activity was the least in the studied matrices.