Determination of phosphate-activated glutaminase activity and its kinetics in mouse tissues using metabolic mapping (quantitative enzyme histochemistry).
Bottom Line: PAG activity was decreased to 22% in the presence of 2 mM 6-diazo-5-oxo-L-norleucine.When compared with liver, kidney and brain, other tissues showed 3-fold to 6-fold less PAG activity.In conclusion, PAG is mainly active in mouse kidney, brain and liver, and shows different kinetics depending on which type of PAG is expressed.
Affiliation: Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands (DB, WT, CJFVN).Show MeSH
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Mentions: PAG showed two distinct patterns of enzyme kinetics (Fig. 7, Table 1). In liver sections, a sigmoidal curve of the reaction velocity versus glutamine concentration was obtained, indicating allosteric regulation of PAG activity. As compared with PAG kinetics in brain and kidney, L-PAG exhibited a relatively high Km of 11.6 mM and a low Vmax of 0.54 µmol/mL/min. PAG kinetics in the brain and kidney showed K-PAG characteristics with Michaelis-Menten kinetics, a relatively low Km for glutamine of 0.6 mM, and a high Vmax of 1.1 µmol/mL/min.
Affiliation: Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands (DB, WT, CJFVN).