Interaction study of a lysozyme-binding aptamer with mono- and divalent cations by ACE
Marie Girardot1, Pierre Gareil, Anne Varenne
1Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences, Ecole Nationale Supérieure de Chimie de Paris (Chimie ParisTech), Paris, France.
Electrophoresis
|February 2, 2010
Summary
Cation interactions significantly influence aptamer conformation and binding. This study used capillary electrophoresis (CE) to investigate how monovalent and divalent cations affect a lysozyme-binding aptamer, revealing buffer-dependent binding constants.
Area of Science:
- Biophysical chemistry
- Analytical chemistry
- Molecular biology
Background:
- Aptamer-target binding is conformation-dependent, influenced by cations.
- Limited research exists on cation-aptamer interactions.
Purpose of the Study:
- Investigate monovalent (Na+, K+, Cs+) and divalent (Mg2+, Ca2+, Ba2+) cation interactions with a 30-mer lysozyme-binding aptamer.
- Utilize capillary electrophoresis (CE) in a mobility shift assay format.
- Examine the influence of buffer composition (phosphate, MOPS) and ionic strength.
Main Methods:
- Capillary electrophoresis (CE) mobility shift assay.
- Estimation of aptamer effective charges in different buffers.
- Corrections for ionic strength and counterion condensation.
- Calculation of apparent binding constants for divalent cations.
Main Results:
- Aptamer effective charges were estimated at 7.4 (phosphate) and 3.6 (MOPS) at 30 mM ionic strength.
- Mobility shifts were influenced by ionic strength, counterion condensation, buffer components, and aptamer conformational changes.
- Apparent binding constants for divalent cations varied depending on the background electrolyte (BGE).
Conclusions:
- Cation type and buffer composition critically affect aptamer behavior and binding.
- CE is a valuable tool for studying cation-aptamer interactions.
- Understanding these interactions is crucial for aptamer-based applications.
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