Chemistry and Biology of Copper-Chelatin
Several years ago Vallee and coworkers isolated and characterized metallothionein from equine kidney (l-3). The presence of cadmium in high levels and a cysteine content of about 30 percent were unusual characteristics of the protein which had a molecular weight of about 10,000. Similar Cd-containing proteins were subsequently isolated from human kidney (3) and equine liver (4). While Cd is either not detectable or present in low levels in tissues of other animals accumulation of the metal in the liver and kidney of a variety of animals could be demonstrated after exposure to the metal. As a result, metallothionein-like proteins containing Cd and characterized by high cysteine content were identified in rabbit liver (5), chicken liver (6) and rat liver (7–11). The existence of two major variants of metallothionein in rabbit liver was shown by Nordberg et al. (5). Polymorphism has also been reported for the equine hepatic and renal proteins (4), the human renal protein (3) and rat liver metallothionein (7, 9). Kimura et al. (10) have recently resolved rat kidney metallothioneins into two forms with identifiable differences in amino acid composition.
KeywordsAmino Acid Composition Rabbit Liver Performic Acid Cysteine Content High Cysteine Content
Unable to display preview. Download preview PDF.