What question did this study set out to answer?

This research aims to explore the utility of protein charge transfer spectra in detecting various molecular interactions and modifications.

February 21, 2026

BPS2026 – Protein CT spectra as a tool to reveal protein-protein, protein-nucleic acid, and post-translational events

Key Points

This research aims to explore the utility of protein charge transfer spectra in detecting various molecular interactions and modifications.
Employs ProCharTS to analyze protein-nucleic acid and protein-protein interactions.
Focuses on dephosphorylation and other post-translational modifications across multiple proteins.
Uses UV-visible absorption measurements in a specific wavelength range to characterize protein interactions.
Post-translational modifications, including acetylation and glycation, were detectable using ProCharTS.
Significant changes in charge transfer spectra were observed in response to dephosphorylation events in proteins.
Distinct responses were noted for protein-DNA binding interactions, suggesting specificity in the detection method.

Abstract

Protein charge transfer spectra (ProCharTS) refers to UV-visible absorption in the 250–800 nm region among proteins that teem with charged amino acids, having clusters of ionized headgroups that lie within a vicinity of 3–8 Å of each other owing to the protein 3D fold. TD-DFT calculations on structure snapshots obtained from MD simulations have revealed that ProCharTS arises by photoinduced electron transfer from donors like polypeptide backbone (PPB); carboxylate anions of Asp/Glu to acceptors like cationic groups of Lys/Arg/protonated His; and PPB (10.1039/c7sc00880e). The molar extinction coefficient of the ProCharTS absorption spectrum is dependent on the charge and spatial proximity among the charged amino acid headgroups in the protein (10.1021/acs.jpcb.9b10071). Consequently, owing to such sensitivity, ProCharTS is a useful label-free tool to detect protein-DNA complex formation as we demonstrate for single chain IHF protein; protein-protein oligomer formation as we show for human lysozyme and α-synuclein; and protein post-translational modifications like acetylation and succinylation of α 3 C, α 3 W, H2A, and HSA proteins; dephosphorylation of α/β-casein proteins; and glycation of HSA. Interestingly, titration of protein against DNA and vice-versa reveals a distinct bell-shaped pattern of fractional increase in ProCharTS intensity for consensus DNA, while a flat profile is observed for non-consensus DNA. Both α and β-casein displayed an increase in molar extinction coefficient in the 350–600 nm region with increasing dephosphorylation. The dephosphorylation of five phosphates in β-casein and eight phosphates in α-casein were clearly detectable using ProCharTS. Increase in ProCharTS absorption displayed a biphasic profile with time upon aggregation of α-synuclein. Further, ProCharTS was sensitive enough to detect addition of one succinyl group to the α 3 C protein in contrast to acetylation, where addition of five acetyl groups was necessary to see noticeable change.

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BPS2026 – Protein CT spectra as a tool to reveal protein-protein, protein-nucleic acid, and post-translational events

Key Points

Abstract

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