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Biomedical subjects

Yaxin Jiang

Publications and source records attributed to Yaxin Jiang.

8 recordsLinked to original sources
PubMed2006

Detection of oncoprotein platelet-derived growth factor using a fluorescent signaling complex of an aptamer and TOTO.

There have recently been advances in the application of aptamers, a new class of nucleic acids that bind specifically with target proteins, as protein recognition probes for biomedical study. The development of a signaling aptamer with the capability of simple and rapid real-time detection of disease-related proteins has attracted increasing interest. We have recently reported a new protein-detection strategy using a signaling aptamer based on a DNA molecular light-switching complex, [Ru(phen)2(dppz)]2+. In this work we have used the commercially available DNA-intercalating dye, TOTO, to replace [Ru(phen)2(dppz)]2+ for detection of oncoprotein platelet-derived growth factor BB (PDGF-BB), a potential cancer marker. Taking advantage of the high affinity of the aptamer to PDGF-BB and the sensitive fluorescence change of the aptamer-TOTO signaling complex on protein binding, PDGF-BB was detected in physiological buffer with high selectivity and sensitivity. The detection limit was 0.1 nmol L(-1), which was better than that of other reported aptamer-based methods for PDGF-BB, including that using [Ru(phen)2(dppz)]2+. The method is very simple with no need for covalent labeling of the aptamer or probe synthesis. It facilitates wide application of the signaling mechanism to the analysis and study of cancer markers and other proteins.

Aptamers, Nucleotide↗
PubMed2005

Aptamer-based ATP assay using a luminescent light switching complex.

With the increasing applications of nucleic acid aptamers as a new class of molecular recognition probes in bioanalysis and biosensor development, the development of general and simple signaling strategies to transduce aptamer-target binding events to detectable signals is demanding. We have developed a new signaling method based on aptamers and a DNA molecular light switching complex, [Ru(phen)2(dppz)]2+, for sensitive protein detection. In this work, we have demonstrated the applicability of this signaling mechanism to small-molecule detection using ATP as a model target. Our results have shown that upon ATP binding to the folded aptamer where [Ru(phen)2(dppz)]2+ intercalated, the conformational change or distortion of the aptamer is large enough to cause a significant luminescence change of [Ru(phen)2(dppz)]2+. By monitoring the ATP-dependent luminescence intensity change, we have achieved ATP detection with high selectivity and high sensitivity down to 1 nM in homogeneous solution. The method is very simple without the needs for covalently labeling aptamers or using costly enzymes and multistep analysis as other reported fluorescence/luminescence assays for ATP. The successful detection of ATP indicates that using the signaling aptamers with [Ru(phen)2(dppz)]2+ is expected to be a general method for aptamer-based target detection.

Adenosine Triphosphate↗
PubMed2005

Molecular signaling aptamers for real-time fluorescence analysis of protein.

Aptamers are a new class of nucleic acids that are selected in vitro for binding target molecules with high affinity and selectivity. They are promising protein-binding molecular probes that rival conventional antibodies for protein analysis. There have been recent advances in the development of molecular signaling aptamers that can transduce target protein binding to sensitive fluorescence signal changes. This facilitates the real time protein monitoring in homogenous solution as well as potentially in vivo. Different signaling strategies of using dual labeled aptamers based on fluorescence resonance energy transfer (FRET), one fluorophore labeled aptamers based on fluorescence anisotropy assay, or other label-free aptamers are reviewed.

Anisotropy↗
PubMed2004

Signaling aptamer/protein binding by a molecular light switch complex.

A novel method of signaling aptamer/protein binding for aptamer-based protein detection has been developed using a molecular light switch complex, [Ru(phen)2(dppz)]2+. The method takes advantage of the sensitive luminescence signal change of [Ru(phen)2(dppz)]2+ intercalating to the aptamer upon protein/aptamer binding. A 37-nt DNA aptamer against immunoglobulin E (IgE) was first tested as a model system. The luminescence of the [Ru(phen)2(dppz)]2+/IgE aptamer decreased with the increase of IgE. By monitoring the luminescence change, we were able to detect the binding events between the aptamer and IgE for IgE quantitation in homogeneous solutions as well as in serum. The assay was highly selective and sensitive with a detection limit of 100 pM for IgE. This new method is very simple and without the need for the covalent coupling of fluorophores to aptamers. The generalizability of the method was demonstrated by the direct detection of two other proteins, oncoprotein platelet derived growth factor-BB (PDGF-BB) using its DNA aptamer and alpha-thrombin using its RNA aptamer. This new approach is expected to promote the exploitation of aptamer-based biosensors for protein assays in biochemical and biomedical studies.

Aptamers, Nucleotide↗
PubMed2004

Measuring specific interaction of transcription factor ZmDREB1A with its DNA responsive element at the molecular level.

Specific interactions between transcription factors and DNA responsive elements are of fundamental importance in understanding how genetic regulatory proteins control gene transcription. Here we have developed a new method of using atomic force microscopy (AFM) to quantitatively study the single molecular specific interaction between ZmDREB1A, a transcription factor from maize, and its DNA responsive element, dehydration-responsive element (DRE) with core sequence A/GCCGAC. It was found that ZmDREB1A bound to both DRE ACCGAC and GCCGAC efficiently. The single molecular interaction forces of ZmDREB1A with DRE A/GCCGAC were determined to be 101 +/- 5 and 108 +/- 3 pN, respectively. The point mutation of ZmDREB1A in its DNA-binding domain or single base substitution of the DRE core sequence greatly reduced the binding affinity, demonstrating the high sensitivity of the AFM measurements. AFM is expected to be a simple, quick, sensitive and reliable method that offers valuable information for the characterization of transcription factors and the identification of their potential DNA responsive elements in functional genomics research.

Arabidopsis Proteins↗
PubMed2004

Study of the effect of metal ion on the specific interaction between protein and aptamer by atomic force microscopy.

We have studied the effect of metal ions on the specific interaction between a protein, immunoglobulin E (IgE), and its 37-nt DNA aptamer with atomic force microscopy (AFM). Protein aptamers are a new class of synthetic single-stranded DNA/RNA oligonucleotide generated from in vitro selection to selectively bind with target proteins. The IgE aptamers have been developed and are expected to be promising reagents in IgE detection and new anti-allergic drug development. It is known that the presence of metal ions in the buffer usually has a strong effect on the affinity of single-stranded DNA for protein. In this work, the effect of two representative monovalent ion and divalent ion on the binding of IgE and the aptamer has been studied at the single-molecule level. The results from the AFM force measurements show that the metal ions not only reduce the single-molecular rupture force but also reduce the number of bonds formed between IgE and the aptamer.

DNA↗
PubMed2003

Specific aptamer-protein interaction studied by atomic force microscopy.

Aptamers are a new class of synthetic DNA/RNA oligonucleotides generated from in vitro selection to selectively bind with various molecules. Due to their molecular recognition capability for proteins, aptamers are becoming promising reagents in protein detection and new drug development. In this study, the specific interaction between the protein immunoglobulin E (IgE) and its 37-nt aptamer has been measured directly by atomic force microscopy. The single-molecule unbinding force between IgE and the aptamer is determined using the Poisson statistical method. The individual unbinding force between IgE and its monoclonal antibody has also been obtained and compared to that between IgE and the aptamer. The results reveal the high affinity of the aptamer to protein, which could match or even surpass that of the antibody to its antigen.

Humans↗