Sulphur metabolism in Paracoccus denitrificans. Purification, properties and regulation of cysteinyl-and methionyl-tRNA synthetase.
Cysteinyl- and methionyl-tRNA synthetases (EC 6.11.-) were purified 1200- and 1000-fold, respectively, from sonic extracts of Paracoccus denitrificans strain 8944, and kinetics, substrate specificity and regulatory properties were determined using the ATP-PPi exchange reaction. Both enzymes had pH optima of approx. 8 and were inhibited by sulphydryl-group reagents. Cysteinyl-tRNA synthetase catalysed L-selenocysteine- and alpha-aminobutyric acid-dependent ATP-PPi exchange and methionyl-tRNA synthetase catalysed L-homocysteine-, L-selenomethionine- and norleucine-dependent ATP-PPi exchange. Both enzymes were inhibited by O-acetylserine. Cysteinyl-tRNA synthetase activity was stimulated by methionine and methionyl-tRNA synthetase activity was stimulated by sulphide, cysteine, and cysteic acid.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000302:isolation & purification / Q000378:metabolism*; D003545:Cysteine / Q000096:biosynthesis; D004492:Edetic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006877:Hydroxamic Acids / Q000378:metabolism; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D008718:Methionine-tRNA Ligase / Q000302:isolation & purification / Q000378:metabolism; D010231:Paracoccus denitrificans / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism
D006877:Hydroxamic Acids; D010710:Phosphates; D000255:Adenosine Triphosphate; D004492:Edetic Acid; D008715:Methionine; D000604:Amino Acyl-tRNA Synthetases; D008718:Methionine-tRNA Ligase; D003545:Cysteine