Fluorescent intensity assay for protein or peptide binding to nucleic acids

A method for assaying binding between at least one fluorophore-labeled compound and at least one unlabeled compound, said method comprising detecting a quenching effect on fluorescence emitted by said at least one fluorophore-labeled compound resulting from said binding, said quenching effect detecting comprising:

• providing a test medium comprising said at least one fluorophore-labeled compound and said at least one unlabeled compound;
• irradiating said test medium with radiation effective to cause said at least one fluorophore-labeled compound to emit fluorescent light;
• and
• comparing a fluorescent intensity of said fluorescent light with a reference fluorescent intensity of a reference medium, wherein said quenching effect and said specific binding are detected when said fluorescent intensity is less than said reference fluorescent intensity,
• wherein:
• (a) said binding is specific and other than nucleobase to nucleobase;
• (b) said method is conducted:
• (i) without separating complexes of said at least one fluorophore-labeled compound and said at least one unlabeled compound from said at least one fluorophore-labeled compound prior to said quenching effect detecting;
• and
• (ii) without providing a signal quenching agent to quench said emitted fluorescence;
• and
• (c) said at least one fluorophore-labeled compound is:
• (i) a labeled nucleic acid to which said fluorophore is covalently bound and said at least one unlabeled compound is an unlabeled protein;
• or
• (ii) a labeled protein and said at least one unlabeled compound is an unlabeled nucleic acid.