Effects of semicarbazide on oxidative processes in human red blood cell membranes.

Semicarbazide can interfere with oxidative processes in the red blood cell membrane via different modes of action. Treatment of human red blood cell membranes with O3, results, among other effects, in cross-linking of membrane proteins and inhibition of glyceraldehyde-3-phosphate dehydrogenase activity. Semicarbazide inhibits these effects by acting as an O3 scavenger. The effect of semicarbazide as an O3 scavenger is complicated by the fact that ozonolysis of semicarbazide yields a product that causes inhibition of glyceraldehyde-3-phosphate dehydrogenase. Glyceraldehyde-3-phosphate dehydrogenase inhibition can also be provoked by incubation of membrane suspensions with O3-treated phospholipids. Semicarbazide prevented this effect by interaction with an inhibitory O3-phospholipid reaction product. Protoporphyrin-induced photodynamic cross-linking of membrane proteins is chemically distinct from O3-induced cross-linking. Photodynamic cross-linking is also inhibited by semicarbazide, in this case via reaction with a histidine photooxidation product.