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Inhibitory effect of polyelectrolytes on oligomeric enzymes.
E A Saburova1, M E Bobreshova, L I Elphimova
1Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142292, Russia. saburova@mail.ru
Biochemistry. Biokhimiia
|September 26, 2000
Summary
Negatively charged polyelectrolytes inactivate oligomeric enzymes like lactate dehydrogenase (LDH) and glutamate dehydrogenase (GDH) by disrupting their structure. This effect is more potent than with monomers, with inhibition reversed by excess substrate.
Area of Science:
- Biochemistry
- Enzyme kinetics
- Polymer science
Background:
- Oligomeric enzymes possess complex structures crucial for their function.
- Polyelectrolytes are polymers with charged groups, known to interact with biomolecules.
- Understanding these interactions is key to enzyme stability and drug development.
Purpose of the Study:
- To investigate the impact of polyelectrolytes on the stability and catalytic activity of oligomeric enzymes.
- To compare the effects of polyelectrolytes with their monomeric counterparts.
- To elucidate the mechanism of polyelectrolyte-enzyme interaction.
Main Methods:
- Fluorescent spectroscopy to assess enzyme structure.
- Steady-state kinetic assays to measure enzyme activity.
- Enzyme inhibition studies with varying polyelectrolyte concentrations.
Main Results:
- Negatively charged polyelectrolytes (polystyrene sulfonate, polymethacrylate, polyphosphate) induced structural damage (tertiary and secondary) in LDH and GDH.
- Complete enzyme inactivation occurred at pH < 7, with polyelectrolytes being significantly more potent inhibitors than monomers.
- Substrate (pyruvate) affinity remained unchanged, and inhibition was reversible with excess substrate.
Conclusions:
- The oligomeric structure of enzymes mediates a unique interaction with polyelectrolytes, distinct from their effect on monomeric enzymes.
- Polyelectrolytes disrupt the quaternary structure of oligomeric enzymes, leading to inactivation.
- The enzyme-disrupting effect increases with the hydrophobicity of the polyelectrolyte chain.