The role of ascorbic acid in cell metabolism: between gene-directed functions and unpredictable chemical reactions

Ascorbic acid (AA) acts in the cell as an electron donor in a number of catalysed and non-catalysed reactions. This accounts for its involvement in many different physiological phenomena. Much attention has been directed to the study of non-catalysed ≪unpredictable≫ chemical reactions, in which AA has the general role of ≪antioxidant molecule≫, but this is not sufficient to explain the apparent ≪pleiotropic action≫ of AA. An increasing amount of data supports the view that AA is specifically required for the activity of 2-oxoacid-dependent dioxygenases (2-0DDs), a class of enzymes including those regulating the synthesis of hydroxyproline-containing proteins and hormones in both plants and animals. Understanding that the role of AA in cell metabolism is much wider than generally assumed, will allow researchers to focus on its ≪gene-directed functions≫, leading to actual advances in many fields of biological research.