The transport of glutamate, apparently a primary energy source for Coxiella burnetii, has been examined. C. burnetii is shown to possess a pH-dependent active transport system for L-glutamate with an apparent Kt of 61.1 microM and Vmax of 8.33 pmol/s per mg at pH 3.5. Both L-glutamine and L-asparagine competitively inhibited transport of glutamate, but D-glutamate, L-aspartate, L-glutamate-gamm...

Identification of physiological and environmental factors that limit efficient growth of hyperthermophiles is important for practical application of these organisms to the production of useful enzymes or metabolites. During fed-batch cultivation of Sulfolobus solfataricus in medium containing L-glutamate, we observed formation of L-pyroglutamic acid (PGA). PGA formed spontaneously from L-glutam...

The transport of L-cystine into cells of the mammalian brain is an essential step in the supply of cysteine for synthesis of the antioxidant glutathione. Uptake of L-cystine in rat brain synaptosomes occurs by three mechanisms that are distinguishable on the basis of their ionic dependence, kinetics of transport and specificity of inhibitors. Almost 90% of L-cystine transport is by a low-affini...

The amino acids L-glutamate and L-aspartate depolarize H1 horizontal cells in the perfused goldfish retina but only at millimolar concentrations. The effects of L-glutamate (but not of L-aspartate) are potentiated approximately 15-fold by exposure to D-aspartate. D-Aspartate blocks acidic amino acid uptake in goldfish retina, so that the potentiation of L-glutamate may be produced by an increas...

Stopped flow studies of the oxidative deamination of L-glutamate by TPN and beef liver glutamate dehydrogenase were performed at pH 6.5 and 7.6. At each pH value, the initial burst slopes obey an equation of the form: e/v = 40 + dd(TPN) + h/bglutamate) + &/(TPN)(L-glutamate). The agreement of dissociation constants for enzyme-TPN and enzyme-L-glutamate binary complexes obtained from the r#~ val...

Human erythrocytes have a low basal permeability to L-glutamate and are not known to have a functional glutamate transporter. Here, treatment of human erythrocytes with arsenite was shown to induce the uptake of L-glutamate and D-aspartate, but not that of D-glutamate or L-alanine. The majority of the arsenite-induced L-glutamate influx was via a high-affinity, Na(+)-dependent system showing ch...

Stopped flow studies of the oxidative deamination of L-glutamate by TPN and beef liver glutamate dehydrogenase were performed at pH 6.5 and 7.6. At each pH value, the initial burst slopes obey an equation of the form: e/v = 40 + dd(TPN) + h/bglutamate) + &/(TPN)(L-glutamate). The agreement of dissociation constants for enzyme-TPN and enzyme-L-glutamate binary complexes obtained from the r#~ val...

Human erythrocytes have a low basal permeability to L-glutamate and are not known to have a functional glutamate transporter. Here, treatment of human erythrocytes with arsenite was shown to induce the uptake of L-glutamate and D-aspartate, but not that of D-glutamate or L-alanine. The majority of the arseniteinduced L-glutamate influx was via a highaffinity, Na -dependent system showing charac...