Bio-Rad’s New ProteOn™ HTE Sensor Chip Suitable for Label-Free Analysis of Protein–Small Molecule Interactions

Comparison of mono-NTA and tris-NTA binding to His-tagged proteins
Comparison of mono-NTA and tris-NTA binding to polyhistidine-tagged proteins. A, Mono-NTA is the traditional method for capturing polyhistidine-tagged proteins but achieves weak binding and results in ligand drift, unstable baselines, distorted kinetic results, and inaccurate fitting to a kinetic model. B, ProteOn trivalent tris-NTA complexes improve binding stability and increase binding selectivity to polyhistidine-tagged molecules. Ni-NTA () binding to histidine () occurs after activation with Ni2+.

Demonstrates Better Performance, Lower Costs than Competing Chips

Hercules, CA — January 3, 2012 —Bio-Rad Laboratories, Inc.’s ProteOn™ HTE Sensor Chip provides a robust solution for pharmaceutical researchers studying the interaction of polyhistidine-tagged protein with small molecule drugs using surface plasmon resonance.

The chip’s innovative tris-NTA coated surface uses three NTA molecules instead of the traditional monomer version of the molecule. Tris-NTA yields a stronger binding interaction with the target, resulting in improved data quality compared to other biosensor solutions for capturing polyhistidine-tagged targets.

“In conversations with our customers and collaborators, we found that few satisfactory options exist today for scientists studying label-free histidine-tagged protein interactions,” said Jill Raymond, Bio-Rad Marketing Manager, Protein Interactions Technologies.

Other options that are available may result in the protein complex leaching off the surface, rendering the surface unsuitable for reuse. And data analysis may require intensive software corrections.

“The unfulfilled promises of other biosensor providers in this area were leaving our customers frustrated,” Raymond said. “This new chip, coupled with the previously launched HTG sensor chip for large molecule applications, means that Bio-Rad now provides a complete solution for customers wanting to work with polyhistidine-tag captured proteins in both small and large molecule applications.”

Better Performance
Used with Bio-Rad’s high-throughput ProteOn XPR36 system, the HTE sensor chip employs a tris-NTA complex on its surface to bind polyhistidine-tagged molecules. This allows researchers to improve binding stability, specificity, and data quality while reducing ligand decay. Bio-Rad has demonstrated that binding stability of polyhistidine-tagged proteins on the HTE sensor chip increased by up to 50% over mono-NTA chips and were approximately twice as selective.

“We’ve found that Bio-Rad’s new HTE sensor chips are capable of capturing high densities of many polyhistidine-tagged proteins, making it possible to characterize the binding of small molecules,” said Dr David Myszka, founder of Biosensor Tools, an SPR biosensor contract services and training provider.

Improved Reusability
Binding via polyhistidine tag is reversible. The HTE sensor chip performs better than anti-His capture surface solutions since it can be regenerated and does not require a change in the researcher's workflow.

This ability to reuse the HTE sensor chip multiple times eliminates chip-to-chip variability, enhances reproducibility, and decreases cost per data point by 90% compared to other commercially available chips, which have limited to no ability to be regenerated or reused.

“I love that the HTE sensor chips can be regenerated with a mixture of EDTA/SDS/NaOH and then still bind just about the same amount of target,” Myszka said.

The ProteOn HTE sensor chip also enables on-chip purification; i.e., capturing target proteins from crude media, thereby saving time, sample, and money required for purification. Earlier this year, Bio-Rad demonstrated a proof-of-concept SPR-MS workflow showing how the company’s SPR chips can be placed directly into a MALDI ionization chamber for mass spectrometry.

For more information on the ProteOn HTE sensor chip, visit To learn more about the ProteOn XPR36 system, visit

About Bio-Rad
Bio-Rad Laboratories, Inc. (NYSE: BIO and BIOb) has remained at the center of scientific discovery for more than 50 years, manufacturing and distributing a broad range of products for the life science research and clinical diagnostic markets. The company is renowned worldwide among hospitals, universities, and major research institutions, as well as biotechnology and pharmaceutical companies, for its commitment to quality and customer service. Founded in 1952, Bio-Rad is headquartered in Hercules, California, and serves more than 100,000 research and industry customers worldwide through its global network of operations. The company employs more than 6,800 people globally and had revenues exceeding $1.9 billion in 2010. For more information, please visit

For more information contact:
Laura Moriarty
Bio-Rad Laboratories, Inc.

Ken Li
Chempetitive Group
312-997-2436 x 109