Structural characterization of human glyoxalase II as probed by limited proteolysis

Human glyoxalase II is partially proteolyzed by trypsin, under non denaturing conditions, only at the level of the C-terminal region. The proteolytic cleavage resulted in an inactivation of the enzyme without loss of the secondary structure. Sodium dodecyl sulphate polyacrylamide gel-electrophoresis and microsequence analysis showed that the glyoxalase II is proteolyzed at the level of Arg 184 and Lys 230 and undergoes a third cleavage in a region located at the beginning of the supposed C-terminal domain. The proteolysis occurs either in the presence or in the absence of specific inhibitors. Our limited proteolysis experiments and secondary structure prediction give evidence for the presence of two domains characterized by different pattern of secondary structure.