STEREOSELECTIVE SYNTHESIS OF STABLE ISOTOPE LABELED L-ALPHA-AMINO ACIDS - THE ENZYMATIC PREPARATION OF C-13-LABELED L-GLUTAMIC ACIDS

We have developed methods for the preparation of L-glutamic acid, isotopically labeled with C-13, using commercially available purified enzymes. The procedure is sufficiently versatile that L-glutamic acid may be labeled at any carbons or any combination of carbons using C-13-labeled pyruvate, acetate and bicarbonate as isotopically labeled precursors. Using the strategy outlined, we have demonstrated the methodology using as an example the preparation of millimolar quantities of L-[1-C-13], L-[4-C-13], L-[5-C-13] and L-[1,3,4-C-13(3)]glutamic acid in a one-pot incubation. We also outline methods for the preparation of C-13-labelled L-malate and citrate.