Inhibition of liver Golgi glycosylation activities by carbonyl products of lipid peroxidation.

The present report deals with the investigation of the effect of 4-hydroxy-trans 2,3-nonenal (HNE), hexanal (HEX) and malondialdehyde (MDA), the major products of lipid peroxidation, on the glycosylation pathway of rat liver Golgi apparatus. Defined concentrations of the aldehydes were added to isolated fractions of formative (F3) and secretory (F1 + F2) Golgi compartments, then incubated at 37 degrees C for 10 min. At the end of the incubation the activity of galactosyl-(GT) and sialyl-(ST)transferases, the main enzymes of the terminal protein and lipoprotein glycosylation, was evaluated. A significant impairment of both these activities was observed with HNE and HEX but not with MDA. These data suggest that aldehydes generated during peroxidation reactions are able to impair the protein and lipoprotein maturation mechanism which is normally achieved through a complete glycosylation.