Labelling of l-Isoleucine tRNA Ligase from Escherichia coli with l-Isoleucyl-bromomethyl Ketone

Diauxie used as a microbiological assay for L-isoleucine or L-valine in Escherichia coli.

FIG. 1. Diauxic lag of cuiltures conitaining valine and isoleucine. All cultures were grown by shakinig (330 rev/ min) at 37 C in medium containing 2.0 g ofNaH2PO4 O H20, 7.0 g ofK2HP04, 2.0 g of (NH4)2SO4, 0.2 g of MgSO4 v 7H20 and I mg of thiamine hydrochloride in I liter of distilled water. Overnight cultures grown in 0.2%o glucose were harvested by centrifugation during exponential phase, r...

Homology of yeast mitochondrial leucyl-tRNA synthetase and isoleucyl- and methionyl-tRNA synthetases of Escherichia coli.

Respiratory deficient mutants of Saccharomyces cerevisiae previously assigned to complementation group G59 are pleiotropically deficient in respiratory chain components and in mitochondrial ATPase. This phenotype has been shown to be a consequence of mutations in a nuclear gene coding for mitochondrial leucyl-tRNA synthetase. The structural gene (MSL1) coding for the mitochondrial enzyme has be...

Isoleucyl-tRNA synthetase. A fluorescence study of the binding properties of the synthetase from Escherichia coli.

Interaction of pseudomonic acid A with Escherichia coli B isoleucyl-tRNA synthetase.

Sodium pseudomonate was shown to be a powerful competitive inhibitor of Escherichia coli B isoleucyl-tRNA synthetase (Ile-tRNA synthetase). The antibiotic competitively inhibits (Ki 6 nM; cf. Km 6.3 microM), with respect top isoleucine, the formation of the enzyme . Ile approximately AMP complex as measured by the pyrophosphate-exchange reaction, and has no effect on the transfer of [14C]isoleu...

Crystalline L-ribulokinase from Escherichia coli.

r.-Ribulokinase has been purified and crystallized from induced cultures of Escherichia coli B/r mutant araA-2, a hyperproducer of this enzyme. The enzyme appears homogeneous by Sephadex G-200 column chromatography and sedimentation pattern. Recrystallization does not increase its specific activity. Acrylamide gel disc electrophoresis at pH 8.3 shows a trace of a slower component, not exceeding...