401. Fructose 1,6-bisphosphatase: the role of lysosomal enzymes in the modification of catalytic and structural properties.
- Author
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Pontremoli S, Melloni E, Balestrero F, Franzi AT, De Flora A, and Horecker BL
- Subjects
- Animals, Catalysis, Electrophoresis, Polyacrylamide Gel, Fructose-Bisphosphatase analysis, Hydrogen-Ion Concentration, Liver cytology, Mice, Microsomes, Liver enzymology, Mitochondria, Liver enzymology, Molecular Conformation, Peptide Hydrolases metabolism, Periodicity, Rabbits, Seasons, Subtilisins metabolism, Subtilisins pharmacology, Fructose-Bisphosphatase metabolism, Liver enzymology, Lysosomes enzymology, Peptide Hydrolases physiology
- Abstract
Seasonal variations in the properties of rabbit-liver fructose 1,6-bisphosphatase have now been linked to corresponding changes in the levels of proteolytic activity in the liver extracts. Incubation of native fructose 1,6-bisphosphatase with purified liver lysosomes causes a 3-fold increase in catalytic activity at pH 9.2, with a smaller, and variable, decrease in activity tested at pH 7.5. These changes in catalytic properties are accompanied by the appearance of a smaller subunit, as was previously reported for the enzyme treated with subtilisin. AMP, a negative modulator of fructose bisphosphatase activity, protects against this action of lysosomes. This proteolytic modification of fructose bisphosphatase by lysosomal enzymes may play a role in the modulation of gluconeogenesis.
- Published
- 1973
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