Selenophosphate synthetase

Figure 28-12. Selenocysteine (top) and the reaction catalyzed by selenophosphate synthetase (bottom).

All selenium-containing proteins and enzymes in animals, microorganisms and plants incorporate selenocysteine non-specifically105 or as part of Se-dependent antioxidant enzymes such as glutathione peroxidase, (EC 1.11.1.9) which has a Se-cysteine residue in its active site.116 120 An active form of Se, selenophosphate, is produced by selenophosphate synthetase in several bacteria. This active form is required for the production of Secys-tRNA, a precursor for Se-cysteine.121 In a similar vein, a Se-containing modified-tRNA nucleoside, 5-methylaminomethyl-2-selenouridine, encodes a selenouridine synthase which replaces sulfur in tRNA with selenium.122... 

Figure 1 Overview of specific use of seienium in bioiogical systems. Selenium can be incorporated into macromolecules in at least three separate pathways. From the reduced form of selenide, selenium is activated to selenophosphate by the action of the enzyme selenophosphate synthetase (SPS or SelD). This activated form is then used as a substrate for pathway-specific enzymes that lead to (1) insertion as selenocysteine into proteins during translation (selenoproteins), (2) incorporation into tRNA molecules as mnm Se U or Se U, and (3) insertion into a unique class of molybdoenzymes as a labile, but required, cofactor. The need for activation to selenophosphate has been demonstrated in all cases at the genetic and biochemical level, with the exception of the labile selenoenzymes, where activation of selenium has only been proposed based on proximity of genes within an operon encoding SPS and a molybdoenzyme. ...

Selenophosphate synthetase Selenoprotein synthesis Escherichia coli 96-98... 

Deiodonase 1 Deiodonase 2 Deiodonase 3 Selenophosphate synthetase 2 Selenoprotein P Selenoprotein W Selenoprotein H Selenoprotein I Selenoprotein K Selenoprotein M Selenoprotein N Selenoprotein O Selenoprotein R (MsrB) Selenoprotein S Selenoprotein T Selenoprotein V Sept 5 (15kDa selenoprotein)... 

RNA POLYMERASES SELENOPHOSPHATE SYNTHETASE SHIKIMATE KINASE SULFATE ADENYLYLTRANSFERASE TUBULIN TYROSINE LIGASE UBIQUITIN-PROTEIN LIGASES d-XYLULOKINASE ATP-dependent protease La,... 

SELENOPHOSPHATE SYNTHETASE STARCH PHOSPHORYLASE SUCCINYL-CoA SYNTHETASE SUCROSE PHOSPHORYLASE TUBULIN.TYROSINE LIGASE ORTHOPHOSPHATE CONTINUOUS ASSAY Orthovanadate,... 

SELENOPHOSPHATE SYNTHETASE SELENOPHOSPHATE SYNTHETASE SELF-ABSORPTION Self-activating process,... 

Selenophosphate Synthetase. This enzyme is required for the intracellular synthesis of selenoproteins via a mono-selenium phosphate intermediate. 

Selenophosphate synthetase Required for biosynthesis of selenophosphate, the preoursor of selenooysteine, and therefore for selenoprotein synthesis... 

Selenophosphate synthetase Synthesizes selenophospate from selenide + ATP as first step in selenocysteine synthesis during Se incorporation into selenoproteins... 

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