title: L-[1-11C]leucine: routine synthesis by enzymatic resolution.
abstract: L-[1-11C]leucine, suitable for the determination of cerebral protein synthesis rates in man using positron emission tomography, has been synthesized using a modified Bucherer-Strecker reaction sequence. The isolation of the pure L-amino acid isomer from the enantiomeric mixture, initially obtained using either an open or closed reaction vessel, was achieved using a D-amino acid oxidase/catalase enzyme complex immobilized on a Sepharose support. The O2 required by the D-amino acid oxidase as the hydrogen acceptor was supplied by catalase. The L-[1-11C]leucine was obtained with a radiochemical purity of greater than 99% and with a radiochemical yield of 25%. Using a remote, semiautomated synthesis system, typical production time was 30-40 min after preparation of H11CN. The use of immobilized enzymes for rapid and effective resolution of amino acid enantiomers eliminates the possibility of protein contamination and assures the production of a sterile, pyrogen-free product.
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D002250:Carbon Radioisotopes; D002845:Chromatography; D006801:Humans; D007553:Isotope Labeling; D007930:Leucine; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D013237:Stereoisomerism; D014055:Tomography, Emission-Computed
chemical_list: D002250:Carbon Radioisotopes; D009419:Nerve Tissue Proteins; D007930:Leucine