Emerging applications of site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) to study food protein structure, dynamics, and interaction

Statistical modeling of in vitro pepsin specificity

“…Unfortunately, protein structural changes depending on pH are not yet determined for the six proteins studied here, making the physicochemical parameters and structural features impossible to adjust to the effective conditions of in vitro digestion. Another limitation of the study lies in that protein dynamics could not be considered due to a lack of available data, whereas it is a major parameter for protein properties and interactions with enzymes (Li, Pan, Yang, Rao, & Chen, 2021;Timmer et al, 2009). The "static" PDB structures used in the present study, that are "mean" structures, does not enable to reflect this dynamic dimension of protein features.…”

Accessing Properties of Molecular Compounds Involved in Cellular Metabolic Processes with Electron Paramagnetic Resonance, Raman Spectroscopy, and Differential Scanning Calorimetry

“…The SDSL-EPR technique involves introducing a paramagnetic probe (usually a nitroxide spin label) at a specific site in the biomolecule of interest, which can then be detected by EPR spectroscopy. By monitoring the EPR spectrum of spin labels, information about the local environment and mobility of the labelled site can be obtained and can be used to infer structural and dynamic changes in the biomolecule [99].…”

Is Cys(MTSL) the Best α-Amino Acid Residue to Electron Spin Labeling of Synthetically Accessible Peptide Molecules with Nitroxides?

“…They were utilized for seminal measurements of distances in isolated proteins 6−14 and within cells 15−17 for analyzing conformational transitions of the prion protein, 18 for unraveling DNA mechanisms, 19−21 for investigating conformation, aggregation, and membrane interactions of peptaibols, 22−27 for studying peptide distribution and mobility on solid supports, 28,29 for understanding host−guest interactions in supramolecular chemistry, 30 and more recently for examining proteins of interest to food science. 31 In any case, here it is fair to mention that in recent years, additional promising approaches different from nitro- xides have been utilized for assessing distances between free radical moieties in proteins [e.g., lanthanide (Gd 3+ ) tags, 32 double His-Cu 2+ -based labels, 33 and trityl (triarylmethyl)based labels 34,35 ]. Two very popular nitroxide probes in peptide/protein (including protein peptidic fragments) investigations are the C α -tetrasubstituted α-amino acid TOAC (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) 36−41 (Figure 1) and MTSL (methanethiosulfonate spin labels; 1-oxyl-2,2,5,5tetramethylpyrroline-3-methyl) nitroxide 42 selectively reacts with the side-chain thiol group of the coded Cys residue to generate Cys(MTSL) (Figure 1).…”

“…In this context, nitroxide electron spin labels are by far the most used probes. They were utilized for seminal measurements of distances in isolated proteins − and within cells − for analyzing conformational transitions of the prion protein, for unraveling DNA mechanisms, − for investigating conformation, aggregation, and membrane interactions of peptaibols, − for studying peptide distribution and mobility on solid supports, , for understanding host–guest interactions in supramolecular chemistry, and more recently for examining proteins of interest to food science . In any case, here it is fair to mention that in recent years, additional promising approaches different from nitroxides have been utilized for assessing distances between free radical moieties in proteins [e.g., lanthanide (Gd 3+ ) tags, double His-Cu 2+ -based labels, and trityl (triarylmethyl)-based labels , ].…”