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Covalent Labeling with Diethylpyrocarbonate for Studying Protein Higher-Order Structure by Mass Spectrometry

Characterizing a protein&#39;s higher-order structure is essential for understanding its function. Mass spectrometry (MS) has emerged as a powerful tool ...

University Of Massachusetts Amherst

Using a methylammonium selective membrane in conjunction with electrochemical impedance spectroscopy, we measured ion migration in methylammonium lead triiodide (MAPbI) with a millisecond (ms) time constant under illumination. These values were consistent with the reported values of ionic conduction in thin-film perovskite solar cells. We monitored an electrochemical impedance response arising from ionic conductivity through MAPbI and a methylammonium selective layer. We could fit this complex impedance response to an intuitive circuit model, which revealed an ionic species moving on a ms time scale. Electrospray ionization mass spectrometry (ESI-MS) revealed direct chemical evidence of methylammonium diffusion into the ion-selective layer. We found no experimental evidence indicating the mobility of lead ions or protons, suggesting that the mobile species observed under illumination is likely methylammonium.

The use of ion-selective membranes to study cation transport in hybrid organic-inorganic perovskites.

Correction for 'The use of ion-selective membranes to study cation transport in hybrid organic-inorganic perovskites' by Emily C. Smith et al., Phys. Chem. Chem. Phys., 2019, 21, 20720-20726.

Correction: The use of ion-selective membranes to study cation transport in hybrid organic-inorganic perovskites.

Obtaining kinetic and thermodynamic information for protein amyloid formation can yield new insight into the mechanistic details of this biomedically important process. The kinetics of the structural change that initiates the amyloid pathway, however, has been challenging to access for any amyloid protein system. Here, using the protein β-2-microglobulin (β2m) as a model, we measure the kinetics and energy barrier associated with an initial amyloidogenic structural change. Using covalent labeling and mass spectrometry, we measure the decrease in solvent accessibility of one of β2m's Trp residues, which is buried during the initial structural change, as a way to probe the kinetics of this structural change at different temperatures and under different amyloid forming conditions. Our results provide the first-ever measure of the activation barrier for a structural change that initiates the amyloid formation pathway. The results also yield new mechanistic insight into β2m's amyloidogenic structural change, especially the role of Pro32 isomerization in this reaction.

Blaise G. Arden

Department of Chemistry

University Of Massachusetts Amherst

Covalent Labeling with Diethylpyrocarbonate for Studying Protein Higher-Order Structure by Mass Spectrometry

Blaise G. Arden

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Chemistry

University Of Massachusetts Amherst

Covalent Labeling with Diethylpyrocarbonate for Studying Protein Higher-Order Structure by Mass Spectrometry

Department of Chemistry