Fast enzymatic preparation of l-DOPA from tyrosine and molecular oxygen: a potential method for preparing [ 15O] l-DOPA

Abstract

A fast, simple and inexpensive enzymatic preparation of 3,4-dihydroxyphenyl- l-alanine ( l-DOPA) from molecular oxygen and tyrosine using mushroom tyrosinase is described. The theoretical incubation time for production of [ 15O] l-DOPA with maximal specific activity from [ 15O]O 2 can be calculated to be about 3 min. In practice, using a specially-designed glass reaction chamber to facilitate the incorporation of gaseous molecular oxygen into l-DOPA with zero lag-time, a 3 min reaction with 1% oxygen in nitrogen results in the formation of approx. 3.9 μmol of l-DOPA, representing conversion of about 14% of the tyrosine substrate. Given access to a supply of [ 15O]O 2, the method should be applicable to the preparation of [ 15O] l-DOPA for use as a PET tracer.