Fig. 1.

Redox states of human serum albumin (HSA). Depending on its redox state, plasma HSA can be divided into reduced HSA (human mercaptoalbumin, HMA) and oxidized HSA (human nonmercaptoalbumin, HNA). Oxidized HSA (HNA) is a mixture of the reversibly and irreversibly oxidized forms. Reversibly oxidized HSA (HNA 1) has mixed disulfide bonds with a thiol compound such as cysteine, homocysteine, or glutathione in the blood. In irreversibly oxidized HSA (HNA 2), the free thiol group is more highly oxidized to sulfenic acid (–SOH), sulfinic acid (–SO₂H), and sulfonic acid (–SO₃H). Alb albumin, Cys cysteine, GSH glutathione GSSG oxidized glutathione, Hcy homocysteine