Michal V. Wolkin

Enthalpy array analysis of enzymatic and binding reactions

Enthalpy arrays enable label-free, solution-based calorimetric detection of molecular interactions in a 96-detector array format. The combination of the small size of the detectors and the ability to perform measurements in parallel results in a significant reduction of sample volume and measurement time compared with conventional calorimetry. We have made significant improvements in the technology by reducing the temperature noise of the detectors and improving the fabrication materials and methods. In combination with an automated measurement system, the advances in device performance and data analysis have allowed us to develop basic enzyme assays for substrate specificity and inhibitor activity. We have also performed a full titration of 18-crown-6 with barium chloride. These results point to future applications for enthalpy array technology, including fragment-based screening, secondary assays, and thermodynamic characterization of leads in drug discovery.

MEMS-Based Enthalpy Arrays

Enthalpy arrays enable label-free detection of a variety of biomolecular interactions, such as protein-ligand binding and enzymatic turnover. Their fabrication using MEMS-technology enables calorimetric measurements at a substantially reduced scale that results in large decreases in the required sample volume compared to conventional microcalorimetry. At the same time, the array format enabled by this miniaturization allows parallel operation to achieve high throughput, making enthalpy arrays a promising tool for proteomics research and drug discovery. This paper focuses on the fabrication of the arrays and presents some recent sensitivity improvements and measurement data: we report an intrinsic noise equivalent temperature difference (NETD) of individual detectors of about 10 muK. Measurement of enzymatic turnover has been successfully demonstrated by phosphorylation of glucose by hexokinase.