抄録
Selenium, an essential trace element, is incorporated into the polypeptide chain of proteins in the form of a selenocysteine residue and demonstrates various physiological activities as selenoproteins. Both organic selenium (selenomethionine, selenocysteine, and selenium-containing proteins) and inorganic selenite serve as an effective selenium source for the biosynthesis of selenoproteins. However, molecular details of metabolism of such selenium sources in the cell are not clear. Because levels of free selenide in cells are extremely low, it is thought that there is a system that efficiently relays a selenium substrate to enzymes involved in selenoprotein biosynthesis. Selenocysteine lyase (SCL) decomposes L-selenocysteine to form an enzyme-bound perselenide (-S-SeH) on the active site cysteine residue and is proposed to function as a selenium delivery protein for selenophosphate synthetase. We revealed the mechanism for selenium-specific substrate recognition of SCL.
