Determination of pKa values in intrinsically disordered proteins

Abstract

Electrostatic interactions in intrinsically disordered proteins (IDPs) and regions (IDRs) can strongly influence their conformational sampling. Side chain pKa values provide information on the electrostatic interaction energies of individual side chains and are required to accurately determine the molecular net charge and charge distribution. Nuclear magnetic resonance (NMR) spectroscopy is the premier method for measuring side chain pKa values as it can detect the ionization states of individual side chains in an IDP or IDR simultaneously. In this section, we outline the use of NMR spectroscopy to determine side chain-specific pKas for each of the nine aspartates, five glutamates, and one histidine contained in a highly acidic 35-residue intrinsically disordered peptide.