Immobilization of glutamate decarboxylase and the preparation of an enzyme column for the synthesis of γ-[13N] aminobutyric acid

The enzyme glutamate decarboxylase is used for the preparation of [13N]aminobutyric acid, a radiopharmaceutical designed for positron emission tomography. To obtain a rapid and high-yield synthesis of the labelled compound, glutamate decarboxylase was immobilized on controlled pore silica beads (pore size 50 nm, particle size 100-200 μm), which were packed into a column. A screening of different immobilization techniques is described. The selected immobilization procedure was further optimized. The synthesis of γ-[13N]aminobutyric acid as a function of enzyme loading, column dimensions and flowrate was investigated. (author)