Methods for the enzymatic synthesis of tyrosine and phenylalanine labeled with nitrogen-13.
L-[13N]Tyrosine and L-[13N]phenylalanine were synthesized using immobilized enzymes by two methods. In method 1, [13N]ammonia is converted to L-[13N]glutamate; transamination with p-hydroxyphenylpyruvate yields L-[13N]tyrosine. [13N]Tyrosine is separated from other labeled intermediates on a Poropak Q column. In method 2, phenylalanine dehydrogenase catalyzes the reversible reductive [13N]amination of either phenylpyruvate or p-hydroxyphenylpyruvate to form L-[13N]phenylalanine or L-[13N]tyrosine, respectively. The feasibility of labeling DOPA and tryptophan with 13N was also demonstrated.
Gelbard
A S
AS
Biophysics Laboratory, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
Cooper
A J
AJ
Asano
Y
Y
Nieves
E
E
Filc-Dericco
S
S
Rosenspire
K C
KC
D004800:Enzymes, Immobilized; D007553:Isotope Labeling / Q000379:methods*; D009590:Nitrogen Radioisotopes; D010649:Phenylalanine; D014443:Tyrosine
D004800:Enzymes, Immobilized; D009590:Nitrogen Radioisotopes; D014443:Tyrosine; D010649:Phenylalanine