Phosphoenolpyruvate carboxykinase. Mn2+ and Mn2+ substrate complexes.

Redox Interaction between Binuclear Mn2(III/IV) Complexes and Binuclear Mn2(II/II) Complexes

A dominant feature of the inorganic chemistry of manganese is the variety of complexes that can be made with different oxidation levels ( + 11+ IV) of the manganese, and living systems have utilized this property in that manganese-containing en­ zymes are involved in many diverse redox func­ tions [1]. The biological function that has generat­ ed most interest is the photosynthetic oxygen evolv...

A physiological role of Mn2+ in the regulation of cytosolic phosphoenolpyruvate carboxykinase from rat liver is unlikely.

A cytosolic cell-free system prepared from rat liver was used to study the effect of bivalent cations on the activity of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK). Steady-state concentrations of oxaloacetate in the range 5-50 microM were generated from increasing concentrations of malate+fumarate (10:1); 2 mM ITP and 3 mM Mg2+ were added as cofactors. Micromolar concent...

Mn2+ and substrate interactions with glutamine synthetase from Escherichia coli.

Loading of doxorubicin into liposomes by forming Mn2+-drug complexes.

A new procedure for loading doxorubicin into large unilamellar vesicles (LUVs) is characterized. It is shown that doxorubicin can be loaded into LUVs composed of sphingomyelin/cholesterol (55:45 mole/mole) in response to a transmembrane MnSO4 gradient in the absence of a transmembrane pH gradient. Complex formation between doxorubicin and Mn2+ is found to be a driving force for doxorubicin upta...

Thiol and Mn2+-mediated Oxidation

Horseradish peroxidase has been shown to catalyze the oxidation of veratryl alcohol (3,4-dimethoxybenzyl alcohol) and benzyl alcohol to the respective aldehydes in the presence of reduced glutathione, MnC12, and an organic acid metal chelator such as lactate. The oxidation is most likely the result of hydrogen abstraction from the benzylic carbon of the substrate alcohol leading to eventual dis...