Homocysteine and Its Disulfide Derivatives

n recent years, there has been an upsurge of interest in elevation of the plasma concentration of homocysteine and closely related metabolites as an independent risk factor for cardiovascular disease (reviewed, for example, in References 1 through 3). Homocysteine itself is a thiol- (sulfhydryl-) containing amino acid, but in normal human plasma and other tissues, a variety of related disulfide derivatives may be present. Different authors have written about these compounds and their effects by using differing terminologies. To promote clarity of meaning and to mini- mize uncertainty, perhaps even confusion, it is important that each article discussing these compounds either defines ex- plicitly the terms and/or abbreviations used or cites a prior publication in which such definitions are provided. Opti- mally, a more uniform consensus terminology will be devel- oped and adopted by the field. This article describes very briefly the structures of the relevant compounds and sets forth terms and abbreviations that, it is hoped, may provide a basis