IDENTIFICATION OF L-METHIONINE S-SULFOXIMINE AS DIASTEREOISOMER OF L-METHIONINE SR-SULFOXIMINE THAT INHIBITS GLUTAMINE SYNTHETASE

The diastereoisomers of L-methionine SR-sulfoximine phosphate have been separated as the corresponding α-N-L-leucyl derivatives by ion-exchange chromatography on an amino acid analyzer; the diastereoisomers of L-methionine SR-sulfoximine and L-methionine SR-sulfoxide can be separated without derivatization. Chromatographic study of the L-methionine sulfoximine phosphate obtained from sheep brain glutamine synthetase inhibited by treatment with L-methionine sR-sulfoximine, adenosine triphosphate, and Mg2+ showed the presence of only one diastereoisomer. Studies with preparations of L-methionine s-sulfoximine and L-methionine R-sulfoximine indicate that only the former diastereoisomer is phosphorylated and inhibits the enzyme. © 1969, American Chemical Society. All rights reserved.