Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:6.3.4.6 (
urease
)
7,490
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The product of the selA gene, selenocysteine synthase, is a pyridoxal 5-phosphate-containing enzyme which catalyzes the conversion of seryl-tRNA(Sec
UCA
) into selenocysteyl-tRNA(Sec
UCA
). Reduction of the aldimine group of pyridoxal 5-phosphate inactivates the enzyme. When reacted with seryl-tRNA(Sec
UCA
) as sole substrate, pyruvate (and possibly also ammonia) is released; in the presence of a high concentration of potassium borohydride, alanyl-tRNA(Sec
UCA
) is formed from seryl-tRNA(Sec
UCA
). These results support the notion that the formyl group of pyridoxal phosphate forms a Schiff base with the alpha-amino group of L-serine with the subsequent 2,3-elimination of a water molecule and the generation of an aminoacrylyl-tRNA(Sec
UCA
) intermediate. ATP is not required for this reaction step, but it is necessary for the conversion of aminoacrylyl-tRNA into selenocysteyl-tRNA(Sec
UCA
) which, in addition, requires the
SELD
protein and reduced selenium. Selenocysteine synthase forms a stable complex with seryl-tRNA(Sec
UCA
) with one tRNA molecule bound per two 50-kDa monomers. The enzyme does not interact with serine-inserting tRNA species. Taken together, the results show that biosynthesis of selenocysteine takes place in the enzyme-bound state and involves the dehydration of L-serine esterified to tRNA in a first step formally followed by the 2,3-addition of HSe- which is provided by the
SELD
protein in an ATP-dependent reaction in the form of a reactive selenium donor molecule.
...
PMID:Selenocysteine synthase from Escherichia coli. Analysis of the reaction sequence. 200 85
