title: Automatic synthesis of L-[beta-11C]amino acids using an immobilized enzyme column.
abstract: We have developed a system for the automatic synthesis of L-[beta-11C]amino acids for i.v. injection by means of enzyme-mediated reactions from 11CO2 via 11CH3I and D,L-[beta-11C]alanine as labeled intermediates. This system, which incorporates an ultrafilter cartridge sterilized by electron beam irradiation and a column packed with immobilized enzymes, was effective for eliminating enzymes and endotoxins that may contaminate the product. Using this system, 1.3 +/- 0.5 GBq of 5-hydroxy-L-[beta-11C]tryptophan with a radiochemical purity of 97.1 +/- 0.6% and a specific activity of 39.6 +/- 8 GBq/mumol a pH value of 4 could be obtained in about 32 min (n = 3, at EOS). No endotoxin, enzyme, or bacteria was detected in the product. L-[beta-11C]dihydroxyphenylalanine (L-[beta-11C]DOPA) was also synthesized using this system.
authors.affiliation: Division of Advanced Technology for Medical Imaging, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Sasaki
authors.forename: M
authors.initials: M
authors.lastname: Ikemoto
authors.forename: M
authors.initials: M
authors.lastname: Mutoh
authors.forename: T
authors.initials: T
authors.lastname: Haradahira
authors.forename: A
authors.initials: A
authors.lastname: Tanaka
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: K
authors.initials: K
authors.lastname: Suzuki
mesh_terms: D000409:Alanine; D000411:Alanine Racemase; D000596:Amino Acids / Q000138:chemical synthesis*; D001331:Automation / Q000295:instrumentation / Q000379:methods; D002245:Carbon Dioxide; D002250:Carbon Radioisotopes; D003605:D-Amino-Acid Oxidase; D004800:Enzymes, Immobilized; D006847:Hydrocarbons, Iodinated; D007553:Isotope Labeling / Q000295:instrumentation / Q000379:methods*; D014442:Monophenol Monooxygenase; D014368:Tryptophanase
chemical_list: D000596:Amino Acids; D002250:Carbon Radioisotopes; D004800:Enzymes, Immobilized; D006847:Hydrocarbons, Iodinated; D002245:Carbon Dioxide; C014055:methyl iodide; D014442:Monophenol Monooxygenase; D003605:D-Amino-Acid Oxidase; D014368:Tryptophanase; D000411:Alanine Racemase; D000409:Alanine