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Filter binding assay


                                                 
                                                    Filter binding assay
Ø The term filter is used in to describe a variety of different techniques in biochemistry, immunology, virology and molecular biology.
Ø The molecular biology a filter binding assay is used to characterized DNA protein interaction.
Ø This particular technique is also referred to as filter assay or a protein binding assay and it can be used to identify and characterised both DNA binding protein and the DNA sequence that can interact with these proteins.
Ø Nitro cellular filter have been used to decade to filter, sterilize solution.
Ø Filter binding assay discovered accidently that DNA can bind to such nitro cellular filter because they lost DNA preparation that`s why what is important is that nitro cellular filter can indeed bind. DNA but only under certain condition. Single stranded DNA binds radially to nitrocellulose filter, but double stranded DNA cannot bind.
Ø Protein does bind to nitrocellulose membrane so it a protein is bounded to a double stranded DNA, then protein DNA complex bind to nitrocellulose membrane.
Experiment – (Assay)
1.    Labelled double stranded DNA poured through a nitrocellulose filter. The amount of labelled DNA in the filter and filter bound material is measured which shows that all the labelled doble stranded DNA material has passed through filter into filtrate. This confirms that double stranded DNA does not bind to nitrocellulose.
2.    A solution of labelled protein is passed through nitrocellulose filter showing that all the protein bound to the filter. This demonstrated that protein can bind themselves to the filter.
3.    Now double stranded DNA binds to protein and mixed with protein, to which DNA bind to protein. Because of protein bind to filter the protein DNA-complex will also bind and the radioactive is found bound to the filter rather than the filtrate.
4.    These filters binding assay is direct measure of DNA protein interaction.
         



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