STEREOSELECTIVE SYNTHESIS OF STABLE ISOTOPE-LABELED L-ALPHA-AMINO ACIDS - BIOSYNTHESIS OF H-2-LABELED, C-13-LABELED, AND N-15-LABELED L-SERINES

We have developed a stereospecific biosynthesis of C-13 and N-15-labeled L-serine which involves the serine-type methylotroph Methylobacterium extorquens AM1. In this biosynthesis, C-3 of serine is derived from methanol while C-2, C-1 and the a-amino group are derived from glycine. By starting with the appropriate labeling precursor, we can produce any of the H-2, C-13 and/or N-15 isotopomers of L-serine. Using a 5-L culture, 40-50 millimoles of L-serine are produced; L-serine and glycine are recovered from the growth medium and then separated chromatographically.