Using 15N‐Ammonium to Characterise and Map Potassium Binding Sites in Proteins by NMR Spectroscopy |
| |
Authors: | Dr Nicolas D Werbeck Dr John Kirkpatrick Dr Jochen Reinstein Dr D Flemming Hansen |
| |
Affiliation: | 1. Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London, WC1E 6BT (UK);2. Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29 69120 Heidelberg (Germany) |
| |
Abstract: | A variety of enzymes are activated by the binding of potassium ions. The potassium binding sites of these enzymes are very specific, but ammonium ions can often replace potassium ions in vitro because of their similar ionic radii. In these cases, ammonium can be used as a proxy for potassium to characterise potassium binding sites in enzymes: the 1H,15N spin‐pair of enzyme‐bound 15NH4+ can be probed by 15N‐edited heteronuclear NMR experiments. Here, we demonstrate the use of NMR spectroscopy to characterise binding of ammonium ions to two different enzymes: human histone deacetylase 8 (HDAC8), which is activated allosterically by potassium, and the bacterial Hsp70 homologue DnaK, for which potassium is an integral part of the active site. Ammonium activates both enzymes in a similar way to potassium, thus supporting this non‐invasive approach. Furthermore, we present an approach to map the observed binding site onto the structure of HDAC8. Our method for mapping the binding site is general and does not require chemical shift assignment of the enzyme resonances. |
| |
Keywords: | ammonium enzyme catalysis HDAC Hsp70 NMR spectroscopy potassium binding |
|
|