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We describe a new method for the assay of sequence-specific DNA-binding proteins in this paper. In this method, the sensitive fluorescence resonance energy transfer (FRET) technology is combined with the common DNA footprinting assay in order to develop a simple, rapid and high-throughput approach for quantitatively detecting the sequence-specific DNA-binding proteins. We named this method as exonuclease III (ExoIII) protection assay with FRET probe. The FRET probe used in this assay was a duplex DNA which was designed to contain one FRET pair in the center and two flanking protein-binding sites. During protein detection, if a target protein exists, it will bind to the two protein-binding sites of the FRET probe and thus protect the FRET pair from ExoIII digestion, resulting in high FRET. However, if the target protein does not exist, the FRET pair on the naked FRET probe will be degraded by ExoIII, resulting in low FRET. Three kinds of recombinant transcription factors including NF-κB, SP1 and p50, and the target protein of NF-κB in HeLa cell nuclear extracts, were successfully detected by the assay. This assay can be extensively used in biomedical research targeted at DNA-binding proteins.

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Genomic DNA polymorphisms are very useful for tracing genetic traits and studying biological diversity among species. Here, we present a method we call the "diversity suppression-subtractive hybridization array" for effectively profiling genomic DNA polymorphisms. The method first obtains the subtracted gDNA fragments between any two species by suppression subtraction hybridization (SSH) to establish a subtracted gDNA library, from which diversity SSH arrays are created with the selected subtracted clones. The diversity SSH array hybridizes with the DIG-labeled genomic DNA of the organism to be assayed. Six closely related Dendrobium species were studied as model samples. Four Dendrobium species as testers were used to perform SSH. A total of 617 subtracted positive clones were obtained from four Dendrobium species, and the average ratio of positive clones was 80.3%. We demonstrated that the average percentage of polymorphic fragments of pairwise comparisons of four Dendrobium species was up to 42.4%. A dendrogram of the relatedness of six Dendrobium species was produced according to their polymorphic profiles. The results revealed that the diversity SSH array is a highly effective platform for profiling genomic DNA polymorphisms and dendrograms.

Biocatalytic design of nanomaterials with enzyme-like activity has been considered as a reliable and promising toolkit for the generation of diagnostic agents in complex biological microenvironments. However, preparation of nanomaterials...

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