Paramagnetic Relaxation Enhancement PRE

An expansion of the method can be found in second-site SLAPSTIC, where, in favorable cases, a second binding site close to the binding site of interest can be used to infer a spin label via a second ligand [116]. 

PRE is generally also present in etPCS experiments and the two approaches can be combined to obtain a defined structure of the ligand and its binding surface towards the receptor [35]. 

---

The magnitude of the paramagnetic relaxation enhancement (PRE) caused by dipolar interactions depends on the square of the gyromagnetic ratios of both involved spins, the inverse sixth power of the inter-spin distance, and the correlation time rc of the vector connecting the two spins. For the transverse relaxation rate enhancement, R2para of a spin I,... 

Paramagnetic relaxation enhancement (PRE) approach was introduced for identifying the asymmetric insertion depths of membrane proteins in lipid bilayers. By applying Mn2+ ions on the outer but not the inner leaflet of lipid bilayers, the sidedness of protein residues in the lipid bilayer was determined. Protein-free lipid membranes with one-side Mn2+ bound surfaces exhibit... 

Paramagnetic relaxation enhancement (PRE) is used approach for determining long-range distance constraints in biomolecular solution NMR spectroscopy. Maltsev et al. showed that P PRE solid-state NMR spectroscopy can be utilized to determine the immersion depth of spin-labeled membrane peptides and proteins. Changes in the P NMR PRE times coupled with modelling studies can be used to describe the spin-label position/amino acid within the lipid bilayer and the corresponding helical tilt and the alpha-helical nicotinic acetylcholine receptor nAChR M2 delta transmembrane is used to show this. This PRE ssNMR technique can be used as a molecular ruler to measure membrane immersion depth. ... 

Fig. 7 Trimer model of S26CR1 Anabaena sensory rhodopsin (ASR). The individual monomers are shown in different colors. R1 side chains are shown in blue. Side chains of residues experiencing large intermolecular paramagnetic relaxation enhancement (PRE) effects and therefore spatially close (< 15 A) to the nitroxide of a neighboring monomer are shown in magenta. Adapted with permission from [189]. Copyright (2012) American Chemical Society...

Paramagnetic relaxation enhancements. The presence of a paramagnetic center in a molecule causes an increase in nuclear spin-lattice relaxation rates R (= Jf ) and spin-spin relaxation rates R2 (= 2 ) of the nearby nuclei, often referred to as paramagnetic relaxation enhancement (PRE). 

---