Higher specific activity of the Escherichia coli glutamyl-tRNA synthetase purified to homogeneity by a six-hour procedure.
The glutamyl-tRNA synthetase (EC 6.1.1.17) of Escherichia coli was purified to homogeneity from the overproducing strain DH5 alpha(pLQ7612) by a two-step procedure that takes only about 6 h and yields 10 mg of enzyme per gram of wet cells. The process consists of a two-phase polyethylene glycol-dextran partition, the top phase of which is diluted and directly applied to an anion-exchange FPLC MonoQ column. The purified enzyme has a specific activity about twice that of the same enzyme purified to homogeneity by the lengthy conventional procedure from either a normal strain or this overproducing strain. This difference is discussed in relation to the generation of microheterogeneity in proteins during their purification.
Lin
S X
SX
Département de biochimie, Faculté des sciences et de génie, Université Laval, Québec, Canada.
Brisson
A
A
Liu
J
J
Roy
P H
PH
Lapointe
J
J
D001426:Bacterial Proteins / Q000302:isolation & purification*; D002498:Centrifugation; D002852:Chromatography, Ion Exchange; D003911:Dextrans; D004790:Enzyme Induction; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005975:Glutamate-tRNA Ligase / Q000302:isolation & purification*; D011092:Polyethylene Glycols; D013997:Time Factors
D001426:Bacterial Proteins; D003911:Dextrans; D011092:Polyethylene Glycols; D005975:Glutamate-tRNA Ligase