Seryl-tRNA synthetase from Bombyx mori. Purification and properties.
Seryl-tRNA synthetase has been purified from the middle silk glands of Bombyx mori by successive chromatography on DEAE-Sephacel, hydroxylapatite, and Bio-Rex 70. The high abundance of seryl-tRNA synthetase in the middle silk glands may result from an adaptation of this organ for the production of the serine-rich protein, sericin. The enzyme is a dimer of Mr = 124,000 consisting of similar or identical subunits and has an oligomeric structure similar to its procaryotic and eucaryotic counterparts. Seryl-tRNA synthetase can be cleaved with trypsin to generate a fragment of Mr = 45,000 on sodium dodecyl sulfate gels; the presence of tRNASer protects the enzyme from tryptic cleavage. Conversion to the Mr = 45,000 species is accompanied by a 90% loss in aminoacyl-tRNA synthetase activity, but only a 20% loss in ATP PPi exchange activity.
Viswanathan
S
S
Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505.
Dignam
J D
JD
D000596:Amino Acids / Q000032:analysis; D000604:Amino Acyl-tRNA Synthetases / Q000302:isolation & purification*; D000818:Animals; D012831:Bombyx / Q000201:enzymology*; D002845:Chromatography; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D017886:Durapatite; D006882:Hydroxyapatites; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D012714:Serine-tRNA Ligase / Q000302:isolation & purification* / Q000378:metabolism
D000596:Amino Acids; D006882:Hydroxyapatites; D046911:Macromolecular Substances; D017886:Durapatite; D000604:Amino Acyl-tRNA Synthetases; D012714:Serine-tRNA Ligase