Merck Millipore Direct Detect protein quantitation system

Merck Millipore has launched the Direct Detect system for rapid, simplified protein quantitation. The system enables infrared-based measurement of amide bonds in protein chains, an intrinsic component of every protein, without relying on amino acid composition, dye-binding properties or redox potential. Conventional assays based on UV-Vis spectroscopy rely on absorbance by a protein’s aromatic amino acids and therefore have limited utility.

In addition to its analytical powers, the system provides a departure from traditional sample prep requirements typical of biomolecular quantitation. After samples are spotted on assay cards, they can be stored in ambient conditions without appreciable change in readout.

Another advantage over conventional assays is that the Direct Detect calibration standard curve requires generation once, which provides additional time savings and ease of use.

The system employs a hydrophilic polytetrafluoroethylene (PTFE) membrane designed to be transparent in most of the infrared spectral region and enables application of biomolecule solutions directly onto the membrane. The system delivers more universally applicable and faster protein quantitation, requiring minimal sample consumption. System accuracy and precision are comparable with results obtained by amino acid analysis, an accurate standard for quantitation, yet can be time consuming and often costly.

Because the system relies on IR-based detection of biomolecules, users can obtain accurate and reproducible protein quantitation in presence of reducing agents and detergents. As a result, the system can measure protein concentrations from 0.2 to 5 mg/mL within seconds, without any bio- or immunochemical staining, directly from samples, including buffered solutions.

The system can also be used to provide information on non-protein sample components, such as lipids and nucleic acids.