Cytosolic glyoxalase II from Arabidopsis thaliana, GLX2-2, was overexpressed and purified to homogeneity using Q-sepharose chromatography. MALDI-TOF mass spectrometry studies indicated a molecular weight of 28,767 Da. Using steady-state kinetics studies, the purified enzyme exhibited a K(m) of 660 ± 100 μM and a k(cat) of 484 ± 92 s-1 at 37°C. Metal analyses demonstrated that the enzyme binds 2.1 ± 0.5 moles of Zn(II) per monomer; the binding of Zn(II) is essential for enzyme viability and activity. Sequence comparison of glyoxalase II enzymes from human, A. thaliana, and yeast and the metallo-β-lactamases reveal that all metal binding ligands of the metallo-β-lactamases are conserved in glyoxalase II enzymes, suggesting that all glyoxalase II enzymes are Zn(II) metalloenzymes. These results and their implications are discussed in light of previous studies on glyoxalase II, and an active site for the glyoxalase II enzymes is proposed.
Bibliographical noteFunding Information:
This work was supported by a Pharmaceutical Researchers and Manufacturers of American Foundation Starter grant (to M.W.C.), an Ohio Board of Regents Research Challenge Grant (to M.W.C.), and NIH grant R15GM55956 (to C.A.M.).
- Arabidoposis thaliana
- Glyoxalase II