Screening apo‐SOD1 conformation stabilizers from natural flavanones using native ion mobility mass spectrometry and fluorescence spectroscopy methods

Abstract

Rationale: A large number of studies have shown that the production of aberrant and deleterious copper zinc superoxide dismutase (SOD1) species is closely related to amyotrophic lateral sclerosis (ALS). Therefore, it is of great significance to screen effective inhibitors of misfolding and aggregation of SOD1 for treating ALS disease. Methods:The interaction between flavanone compounds with apo-SOD1was investigated using native electrospray ion mobility mass spectrometry (native ESI-IM-MS). Binding affinities of ligands were compared using native MS, ESI-MS/MS, collision-induced unfolding, and competitive experiments. The effect of ligands on apo-SOD1 aggregation was investigated using the fluorescence spectroscopy method.Results: The results of MS showed that the binding affinity of liquiritin apioside was the strongest, better than the corresponding monosaccharide and aglycone, indicating that the presence and the number of glycosyl group are beneficial to enhance ligand affinity to protein. The results of fluorescence spectroscopy for inhibiting protein aggregation in vitro were consistent with the binding affinity. In addition, the results of the collision-induced unfolding indicated that liquiritin apioside can slow down the unfolding of the protein. Meanwhile, the results of competition experiment suggested that liquiritin apiosides share different binding sites with naringin and 5-fluorouridine, which are significant for the structural stability of SOD1.Conclusions: This study revealed that the binding of liquiritin apioside can stabilize apo-SOD1 dimer and inhibit the aggregation of apo-SOD1, and illustrated that native ESI-IM-MS is a powerful tool for providing insight into investigating the structureactivity relationship between small molecules and protein, and screening protein conformation stabilizers.

Ion‐mobility tandem mass spectrometry combined with molecular docking to research the interaction between flavonoside isomers and metal‐free superoxide dismutase

“…Loss of metal ions is thought to be one of the causes of structural instability and aggregation of SOD1 6,7 . Therefore, studies pay much attention to screening small molecules that can effectively bind and stabilize SOD1 8–10 …”

“…6,7 Therefore, studies pay much attention to screening small molecules that can effectively bind and stabilize SOD1. [8][9][10] Electrospray ionization mass spectrometry (ESI-MS) has been widely used in analyzing proteins. 11,12 When coupled with ion mobility (IMS), more information on the protein structure can be obtained.…”

The Role of Ion Rotation in Ion Mobility: Ultrahigh-Precision Prediction of Ion Mobility Dependence on Ion Mass Distribution and Translational to Rotational Energy Transfer

“…Ion mobility spectrometry (IMS) separates gas phase ions as they move though a gas under the influence of an electric field. − IMS is often coupled to mass spectrometry (MS), allowing for ion mobility and mass-to-charge ( m/z ) measurements to be made simultaneously, and the combination has been employed in areas of physical and analytical chemistry, which include gas phase structural biology, − chemical kinetics, , isomer separations, − molecular class identifications, and broad “omics” measurements. , The mobility ( K ) of an ion under equilibrium subject to an electric field ( E ) is given by eq : where v d is the net ion relative velocity through the gas in a steady-state condition. The drift velocity of an ion is dependent on the experimental conditions such as the pressure, temperature, and gas identity .…”