Stereochemistry of lysine formation by meso-diaminopimelate decarboxylase from wheat germ: use of proton-carbon-13 NMR shift correlation to detect stereospecific deuterium labeling

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Abstract
The stereochemical course of the wheat germ meso-diaminopimelate (DAP) decarboxylase reaction is compared to that of the decarboxylase isolated from Bacillus sphaericus, which was reported to proceed with an unusual inversion of configuration. Reaction of each enzyme with either unlabeled diaminopimelic acid in D2O or [2,6-2H2]diaminopimelic acid in H2O gave stereospecifically 2H-labeled lysine samples that were derivatized with (-)-camphanoyl chloride and diazomethane. Analysis by 2-dimensional 1H-13C heteronuclear NMR shift correlation spectroscopy with 2H decoupling confirmed the stereochemistry of the B. sphaericus enzyme reaction and showed that the eukaryotic wheat germ meso-DAP decarboxylase also operates with inversion of configuration. This suggests similar mechanisms for the prokaryotic and eukaryotic enzymes, and contrasts the retention mode observed with other pyridoxal phosphate dependent .alpha.-decarboxylases.