Ligand Discovery Using Competition Dialysis: A Comprehensive Review

This report discusses competition dialysis, a method used to discover ligands that bind to nucleic acids with structural selectivity. It explains the principles of dialysis, where solutes diffuse through a semi-permeable membrane, and how this process is applied to identify ligands with preferential binding to specific nucleic acid structures. The report also covers the types of ligands suitable for competition dialysis, emphasizing the importance of a convenient spectroscopic monitor for determining ligand concentrations. Specific examples, such as the use of Dispo Dialyzer units, are provided, along with a discussion of different ligands and their affinities to single-stranded DNA and RNA. The report references key studies, including the Chaires review, which highlights the limitations and potential illusions in determining affinity with other nucleic acid structures like double-stranded DNA and RNA. Desklib offers a variety of study tools and resources, including past papers and solved assignments, to further assist students in understanding complex scientific methodologies.

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Explain competition dialysis;
Competition dialysis refers to a new tool that is used in the discovery of the ligands that are
known to bind to the nucleic acids. These binding are restricted to those nucleic acids with
structural selective activity (Kumar 2012). In this particular method, a common test solution is
used as a reference standard point when a particular type of the structure of nucleic acid is to be
dialysed.After the process of equilibration is achieved,absorbence or fluorescence measurements
are used in the determination of the of the amount of ligand that is bound to each structure.
Sometimes the bounding is on the sequence.
Figure 1.Sample results of competition dialysis extracted from (Sannasi and Santoso 2016).
How can it be used?
The well-known process of dialysis involves flow of one or more solutes by diffusion through a
semi-permeable membrane. Those molecules that are smaller in size as compared to the size of
the pores of the membrane will definitely pass through. Inside the membrane are retained
particles of larger sizes. The process of dialysis is used in the basic science of impurity removal

from solutions or just changing the conditions of the solution that is normally common in the
purification process of the nucleic acids and proteins. Dialysis units are placed into a beaker that
that contains ligand solution. At the point of equilibrium, the concentration of the free ligand is
uniform throughout the system. Greater accumulation of the total binding within the dialysis unit
results from preferential binding of specific structures. Structural selectivity can then be obtained
by measuring the concentration of the ligand in each unit of dialysis.
Ligands choose; can we use any ligand for the competition dialysis?
The competition dialysis process is actually amenable to the study of both soluble and stable
ligands that falls within the chosen buffer. Preparation of concentration that is considered micro
molar can actually be possible with a number of ligands. In cases where the solubility is a
limiting factor, there is addition of DMSO of 1%.The most crucial requirement is that ligand has
a spectroscopic monitor that is convenient in the determination of the ligand concentrations
(Neijssen et al.2017).
Which ligand solution can be useful for that competition dialysis and why?
The ligand that was found useful was 0.5 or 1.0ml Dispo Dialyzer units. This particular ligand
provided 6.28mm2/ml of the area of membrane. The ligand was preferred since it was possible to
re-use the units by having the units removed by membrane after each step of experiment and
replacing it with snakeskin (Rixer 2014).
Examples for different ligands with different affinity and selectivity with their figures.
Single-stranded DNA has index1 with nucleic acid type called poly(dT).The possible size is
264nm.Index 2 is known as poly(dA) with possible size 257nm.Single stranded RNA of index 3

has nucleic acid type called Poly(rG),index 4 poly(rC),index5 poly(rA) and index 6 Poly(rU)
whose sizes are 253nm,269nm,258nm and 260nm respectively
.Check Chaires review for completion dialysis (some of which are nolonger on the market)?
In the Chaires review for 0ther types that include Double stranded DNA,DNA-RNA hybrid,
Double stranded RNA,Triplex DNA or RNA and Quadruplex DNA are not common in the
market.Results have shown affinity to be very illusionary with the displacement of the third
strand and binding to the form that is considered duplex.The samples of DNA and RNA both left
handed species-DNA was observed. Strong affinity exists in AT-rich duplex DNA and AT/AU
rich triplex( Elbourne and Tech 2016).

REFERENCES
Elbourne, M.P. and Tech, B. 2016, HUMAN SERUM ALBUMIN. Ann Arbor, 1050, pp.48106-
1346.
Neijssen, J.J., De Goeij, B., van den Brink, E.N., Labrijn, A.F., Hoet, R., Schuurman, J., Parren,
P. and van de Winkel, J., Genmab AS, 2017. Monoclonal antibodies against c-Met. U.S. Patent
9,657,107.
Rixer, Á., 2014. Health Law and Health Administration in Hungary. Patrocinium.
Kumar, A., Parkesh, R., Sznajder, L.J., Childs-Disney, J.L., Sobczak, K. and Disney, M.D.,
2012. Chemical correction of pre-mRNA splicing defects associated with sequestration of
muscleblind-like 1 protein by expanded r (CAG)-containing transcripts. ACS chemical
biology, 7(3), pp.496-505.
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