Oxidative modification of proteins in chronic alcoholics.

Oxidative modification of proteins is of great importance because of their biological role in transport, enzyme activity, immune response and membrane fluidity. This study investigated the redox status of proteins in plasma, erythrocyte and erythrocyte ghosts of chronic alcoholics; a comparison with subjects affected by chronic viral hepatitis and healthy controls was also performed. Compared to the other groups, chronic active alcoholics showed significant increase of plasma, erythrocyte and erythrocyte ghost concentrations of carbonyl proteins, marker of protein oxidative damage. Also, a significant correlation was noted between daily alcohol intake and plasma levels of carbonyl proteins. The incubation of fresh human plasma with acetaldehyde, but not with ethanol, led to a significant increase of the carbonyl protein production. In conclusion, plasma, erythrocyte and membrane proteins are oxidatively modified in active chronic alcoholics; these changes seem to be related to acetaldehyde rather than ethanol toxicity.