Kenneth J Oh - Academia.edu (original) (raw)

Papers by Kenneth J Oh

Research paper thumbnail of Aberrant crosstalk between insulin signaling and mTOR in young Down syndrome individuals revealed by neuronal‐derived extracellular vesicles

Research paper thumbnail of Highly Sensitive Protein Quantification by Direct Kinetic Fingerprinting of Single Protein Molecules

Research paper thumbnail of Direct kinetic fingerprinting and digital counting of single protein molecules

Proceedings of the National Academy of Sciences

The sensitive and accurate quantification of protein biomarkers plays important roles in clinical... more The sensitive and accurate quantification of protein biomarkers plays important roles in clinical diagnostics and biomedical research. Sandwich ELISA and its variants accomplish the capture and detection of a target protein via two antibodies that tightly bind at least two distinct epitopes of the same antigen and have been the gold standard for sensitive protein quantitation for decades. However, existing antibody-based assays cannot distinguish between signal arising from specific binding to the protein of interest and nonspecific binding to assay surfaces or matrix components, resulting in significant background signal even in the absence of the analyte. As a result, they generally do not achieve single-molecule sensitivity, and they require two high-affinity antibodies as well as stringent washing to maximize sensitivity and reproducibility. Here, we show that surface capture with a high-affinity antibody combined with kinetic fingerprinting using a dynamically binding, low-affi...

Research paper thumbnail of Self-Assembling Nanoparticle Drug Delivery System

Research paper thumbnail of V3 Stain-free Workflow for a Practical, Convenient, and Reliable Total Protein Loading Control in Western Blotting

Journal of Visualized Experiments, 2013

The western blot is a very useful and widely adopted lab technique, but its execution is challeng... more The western blot is a very useful and widely adopted lab technique, but its execution is challenging. The workflow is often characterized as a "black box" because an experimentalist does not know if it has been performed successfully until the last of several steps. Moreover, the quality of western blot data is sometimes challenged due to a lack of effective quality control tools in place throughout the western blotting process. Here we describe the V3 western workflow, which applies stain-free technology to address the major concerns associated with the traditional western blot protocol. This workflow allows researchers: 1) to run a gel in about 20-30 min; 2) to visualize sample separation quality within 5 min after the gel run; 3) to transfer proteins in 3-10 min; 4) to verify transfer efficiency quantitatively; and most importantly 5) to validate changes in the level of the protein of interest using total protein loading control. This novel approach eliminates the need of stripping and reprobing the blot for housekeeping proteins such as β-actin, β-tubulin, GAPDH, etc. The V3 stain-free workflow makes the western blot process faster, transparent, more quantitative and reliable.

Research paper thumbnail of ChemInform Abstract: Beyond Molecular Beacons: Optical Sensors Based on the Binding-Induced Folding of Proteins and Polypeptides

ChemInform, 2009

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Research paper thumbnail of Excimer-Based Peptide Beacons:  A Convenient Experimental Approach for Monitoring Polypeptide−Protein and Polypeptide−Oligonucleotide Interactions

Journal of the American Chemical Society, 2006

While protein-polypeptide and nucleic acid-polypeptide interactions are of significant experiment... more While protein-polypeptide and nucleic acid-polypeptide interactions are of significant experimental interest, quantitative methods for the characterization of such interactions are often cumbersome. Here we described a relatively simple means of optically monitoring such interactions using excimer-based peptide beacons (PBs). The design of PBs is based on the observation that, whereas short peptides are almost invariably unfolded and highly dynamic, they become rigid when complexed with macromolecular targets. Using this binding-induced folding to segregate two pyrene moieties and therefore inhibit excimer formation, we have produced PBs directed against both anti-HIV antibodies and the retroviral transactive response (TAR) RNA hairpin. For both polypeptides, target recognition is accompanied by a roughly 2-fold decrease in excimer emission, thus allowing the detection of their respective targets at concentrations of a few nanomolar. Because excimer emission requires the formation of a tight, precisely oriented pyrene dimer, even relatively trivial binding-induced segregation reduces fluorescence significantly. This suggests that the PB approach will be suitable for monitoring a wide range of peptide-macromolecule recognition events. Moreover, the synthesis of excimer-based PBs utilizes commercially available modified pyrenes in a simple and well-established protocol, making the approach well suited for routine laboratory applications.

Research paper thumbnail of Beyond Molecular Beacons: Optical Sensors Based on the Binding-Induced Folding of Proteins and Polypeptides

Chemistry - A European Journal, 2009

Many polypeptides and small proteins can be readily engineered such that they only fold upon bind... more Many polypeptides and small proteins can be readily engineered such that they only fold upon binding a specific target ligand. This approach couples target recognition with a considerable change in polymer structure and dynamics. Recent years have seen the development of a number of biosensors that couple these large changes to readily measurable optical (fluorescent) outputs. These sensors afford the detection of a wide variety of macromolecular targets including proteins, polypeptides, and nucleic acids. Here we describe the design of such biosensors, from the first iterations as protein engineering experiments, to the development of biosensors targeting a range of protein and nucleic acid targets.

Research paper thumbnail of Chimeric peptide beacons: a direct polypeptide analog of DNA molecular beacons

Chemical Communications, 2007

We have developed a new biosensor architecture, which is comprised of a polypeptide-peptide nucle... more We have developed a new biosensor architecture, which is comprised of a polypeptide-peptide nucleic acid tri-block copolymer and which we have termed chimeric peptide beacons (CPB), that generates an optical output via a mechanism analogous to that employed in DNA-based molecular beacons. † Electronic supplementary information (ESI) available: Thermal melt of the 2bp CPB. Saturable binding of the 3bp CPB. See

Research paper thumbnail of Peptide Beacons:  A New Design for Polypeptide-Based Optical Biosensors

Bioconjugate Chemistry, 2007

Research paper thumbnail of Aberrant crosstalk between insulin signaling and mTOR in young Down syndrome individuals revealed by neuronal‐derived extracellular vesicles

Research paper thumbnail of Highly Sensitive Protein Quantification by Direct Kinetic Fingerprinting of Single Protein Molecules

Research paper thumbnail of Direct kinetic fingerprinting and digital counting of single protein molecules

Proceedings of the National Academy of Sciences

The sensitive and accurate quantification of protein biomarkers plays important roles in clinical... more The sensitive and accurate quantification of protein biomarkers plays important roles in clinical diagnostics and biomedical research. Sandwich ELISA and its variants accomplish the capture and detection of a target protein via two antibodies that tightly bind at least two distinct epitopes of the same antigen and have been the gold standard for sensitive protein quantitation for decades. However, existing antibody-based assays cannot distinguish between signal arising from specific binding to the protein of interest and nonspecific binding to assay surfaces or matrix components, resulting in significant background signal even in the absence of the analyte. As a result, they generally do not achieve single-molecule sensitivity, and they require two high-affinity antibodies as well as stringent washing to maximize sensitivity and reproducibility. Here, we show that surface capture with a high-affinity antibody combined with kinetic fingerprinting using a dynamically binding, low-affi...

Research paper thumbnail of Self-Assembling Nanoparticle Drug Delivery System

Research paper thumbnail of V3 Stain-free Workflow for a Practical, Convenient, and Reliable Total Protein Loading Control in Western Blotting

Journal of Visualized Experiments, 2013

The western blot is a very useful and widely adopted lab technique, but its execution is challeng... more The western blot is a very useful and widely adopted lab technique, but its execution is challenging. The workflow is often characterized as a "black box" because an experimentalist does not know if it has been performed successfully until the last of several steps. Moreover, the quality of western blot data is sometimes challenged due to a lack of effective quality control tools in place throughout the western blotting process. Here we describe the V3 western workflow, which applies stain-free technology to address the major concerns associated with the traditional western blot protocol. This workflow allows researchers: 1) to run a gel in about 20-30 min; 2) to visualize sample separation quality within 5 min after the gel run; 3) to transfer proteins in 3-10 min; 4) to verify transfer efficiency quantitatively; and most importantly 5) to validate changes in the level of the protein of interest using total protein loading control. This novel approach eliminates the need of stripping and reprobing the blot for housekeeping proteins such as β-actin, β-tubulin, GAPDH, etc. The V3 stain-free workflow makes the western blot process faster, transparent, more quantitative and reliable.

Research paper thumbnail of ChemInform Abstract: Beyond Molecular Beacons: Optical Sensors Based on the Binding-Induced Folding of Proteins and Polypeptides

ChemInform, 2009

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Research paper thumbnail of Excimer-Based Peptide Beacons:  A Convenient Experimental Approach for Monitoring Polypeptide−Protein and Polypeptide−Oligonucleotide Interactions

Journal of the American Chemical Society, 2006

While protein-polypeptide and nucleic acid-polypeptide interactions are of significant experiment... more While protein-polypeptide and nucleic acid-polypeptide interactions are of significant experimental interest, quantitative methods for the characterization of such interactions are often cumbersome. Here we described a relatively simple means of optically monitoring such interactions using excimer-based peptide beacons (PBs). The design of PBs is based on the observation that, whereas short peptides are almost invariably unfolded and highly dynamic, they become rigid when complexed with macromolecular targets. Using this binding-induced folding to segregate two pyrene moieties and therefore inhibit excimer formation, we have produced PBs directed against both anti-HIV antibodies and the retroviral transactive response (TAR) RNA hairpin. For both polypeptides, target recognition is accompanied by a roughly 2-fold decrease in excimer emission, thus allowing the detection of their respective targets at concentrations of a few nanomolar. Because excimer emission requires the formation of a tight, precisely oriented pyrene dimer, even relatively trivial binding-induced segregation reduces fluorescence significantly. This suggests that the PB approach will be suitable for monitoring a wide range of peptide-macromolecule recognition events. Moreover, the synthesis of excimer-based PBs utilizes commercially available modified pyrenes in a simple and well-established protocol, making the approach well suited for routine laboratory applications.

Research paper thumbnail of Beyond Molecular Beacons: Optical Sensors Based on the Binding-Induced Folding of Proteins and Polypeptides

Chemistry - A European Journal, 2009

Many polypeptides and small proteins can be readily engineered such that they only fold upon bind... more Many polypeptides and small proteins can be readily engineered such that they only fold upon binding a specific target ligand. This approach couples target recognition with a considerable change in polymer structure and dynamics. Recent years have seen the development of a number of biosensors that couple these large changes to readily measurable optical (fluorescent) outputs. These sensors afford the detection of a wide variety of macromolecular targets including proteins, polypeptides, and nucleic acids. Here we describe the design of such biosensors, from the first iterations as protein engineering experiments, to the development of biosensors targeting a range of protein and nucleic acid targets.

Research paper thumbnail of Chimeric peptide beacons: a direct polypeptide analog of DNA molecular beacons

Chemical Communications, 2007

We have developed a new biosensor architecture, which is comprised of a polypeptide-peptide nucle... more We have developed a new biosensor architecture, which is comprised of a polypeptide-peptide nucleic acid tri-block copolymer and which we have termed chimeric peptide beacons (CPB), that generates an optical output via a mechanism analogous to that employed in DNA-based molecular beacons. † Electronic supplementary information (ESI) available: Thermal melt of the 2bp CPB. Saturable binding of the 3bp CPB. See

Research paper thumbnail of Peptide Beacons:  A New Design for Polypeptide-Based Optical Biosensors

Bioconjugate Chemistry, 2007