title: Efficient Enzymatic Preparation of (13) N-Labelled Amino Acids: Towards Multipurpose Synthetic Systems.
abstract: Nitrogen-13 can be efficiently produced in biomedical cyclotrons in different chemical forms, and its stable isotopes are present in the majority of biologically active molecules. Hence, it may constitute a convenient alternative to Fluorine-18 and Carbon-11 for the preparation of positron-emitter-labelled radiotracers; however, its short half-life demands for the development of simple, fast, and efficient synthetic processes. Herein, we report the one-pot, enzymatic and non-carrier-added synthesis of the (13) N-labelled amino acids l-[(13) N]alanine, [(13) N]glycine, and l-[(13) N]serine by using l-alanine dehydrogenase from Bacillus subtilis, an enzyme that catalyses the reductive amination of α-keto acids by using nicotinamide adenine dinucleotide (NADH) as the redox cofactor and ammonia as the amine source. The integration of both l-alanine dehydrogenase and formate dehydrogenase from Candida boidinii in the same reaction vessel to facilitate the in situ regeneration of NADH during the radiochemical synthesis of the amino acids allowed a 50-fold decrease in the concentration of the cofactor without compromising reaction yields. After optimization of the experimental conditions, radiochemical yields were sufficient to carry out in vivo imaging studies in small rodents.
authors: Radiochemistry and Nuclear Imaging Group, CIC biomaGUNE, Paseo Miramón 182, 20009, San Sebastián, Guipúzcoa, Spain.
authors: Eunice S
authors: ES
authors: da Silva
authors: Radiochemistry Platform, CIC biomaGUNE, Paseo Miramón 182, 20009, San Sebastián, Guipúzcoa, Spain.
authors: Vanessa
authors: V
authors: Gómez-Vallejo
authors: Radiochemistry and Nuclear Imaging Group, CIC biomaGUNE, Paseo Miramón 182, 20009, San Sebastián, Guipúzcoa, Spain.
authors: Zuriñe
authors: Z
authors: Baz
authors: Radiochemistry and Nuclear Imaging Group, CIC biomaGUNE, Paseo Miramón 182, 20009, San Sebastián, Guipúzcoa, Spain. jllop@cicbiomagune.es.
authors: Jordi
authors: J
authors: Llop
authors: Heterogeneous Biocatalysis Group, CIC biomaGUNE, Paseo Miramón 182, 20009, San Sebastián, Guipúzcoa, Spain. flopez.ikerbasque@cicbiomagune.es.|IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013, Bilbao, Bizkaia, Spain. flopez.ikerbasque@cicbiomagune.es.
authors: Fernando
authors: F
authors: López-Gallego
mesh_terms: D000409:Alanine / Q000032:analysis / Q000737:chemistry; D050788:Alanine Dehydrogenase / Q000737:chemistry; D000586:Amination; D000596:Amino Acids / Q000138:chemical synthesis / Q000737:chemistry*; D000818:Animals; D001412:Bacillus subtilis / Q000201:enzymology; D055162:Biocatalysis; D002175:Candida / Q000201:enzymology; D002250:Carbon Radioisotopes; D004789:Enzyme Activation; D005462:Fluorine Radioisotopes; D005560:Formate Dehydrogenases / Q000737:chemistry; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D007651:Keto Acids / Q000737:chemistry; D008810:Mice, Inbred C57BL; D009243:NAD / Q000737:chemistry*; D009590:Nitrogen Radioisotopes; D000072078:Positron Emission Tomography Computed Tomography; D000072760:Single Molecule Imaging / Q000379:methods
chemical_list: D000596:Amino Acids; D002250:Carbon Radioisotopes; C000615233:Carbon-11; D005462:Fluorine Radioisotopes; D007651:Keto Acids; D009590:Nitrogen Radioisotopes; C000615247:Nitrogen-13; D009243:NAD; D005560:Formate Dehydrogenases; D050788:Alanine Dehydrogenase; C000615276:Fluorine-18; D000409:Alanine
keywords: amino acids; biocatalysis; nitrogen-13; positron emission tomography; radiochemistry