Résumé
Equilibrium unfolding experiments provide access to protein thermodynamic stability revealing basic aspects of protein structure-function relationships. A limitation of these experiments stands on the availability of large amounts of protein samples. Here we present the use of the NanoDrop for monitoring guanidinium chloride-induced unfolding by Soret absorbance of monomeric heme proteins. Unfolding experiments using 2 mu l of reactant are validated by fluorescence and circular dichroism spectroscopy and supported with five heme proteins including neuroglobin, cytochrome b(5), and cyanoglobin. This work guarantees 2 orders of magnitude reduction in protein expense. Promising low-cost protein unfolding experiments following other chromophores and high-throughput screenings are discussed. (C) 2013 Elsevier Inc. All rights reserved.