Inactivation and modification of superoxide dismutase by glyoxal: prevention by antibodies

Abstract

Glyoxal is an endogenous compound, the levels of which are increased in various pathologies associated with hyperglycaemia and other related disorders. It has been reported to inactivate critical cellular enzymes by promoting their cross-linking and perpetuates advanced glycation end-product (AGE) formation. In this study, we used superoxide dismutase (SOD) as a model to investigate the ability of specific anti-enzyme antibodies and monomer Fab fragments to protect against glyoxal-induced deactivation and aggregate formation. We found that glyoxal deactivated SOD, in a concentration and time-dependent fashion. The enzymatic activity was monitored spectrophotometrically and it was found that enzyme lost approximately 95% of its original activity, when exposed to 10 mM glyoxal for 120 h. SDS-polyacrylamide gel electrophoresis demonstrated the formation of high molecular weight aggregates in SOD samples exposed to glyoxal. Surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS) showed increase in relative molecular mass (M(r)), upon exposure to glyoxal. Specific anti-enzyme antibodies and monomer Fab fragments markedly inhibited SOD deactivation caused by glyoxal and decreased the extent of cross-linking or formation of aggregates. This protection by the antibodies or Fab fragments was specific since, other non-specific antibodies were not able to protect SOD. Previously, antibodies have been used to prevent aggregation of beta-amyloid peptides in Alzheimer and prion-protein disease. Our findings provide a new perspective, for use of antibodies to prevent the biomolecules against glycation-induced deactivation and alteration.