TY - JOUR

T1 - CIDNP study of photoinduced electron transfer in His-Glu-Tyr-Gly peptide and its conjugate His-Gln(BP)-Tyr-Gly

AU - Fishman, Natalya N.

AU - Herr, Kevin

AU - Morozova, Olga B.

AU - Zhukov, Ivan V.

AU - Geniman, Maksim P.

AU - Brodrecht, Martin

AU - Wissel, Till

AU - Buntkowsky, Gerd

AU - Yurkovskaya, Alexandra V.

N1 - This work was supported by the Russian Science Foundation (project #23-73-01101) and the German Research foundation under contract Bu-911/29-1. We thank the Ministry of Science and Higher Education of the Russian Federation for granting access to the NMR equipment.

PY - 2025/6/20

Y1 - 2025/6/20

N2 - Photoinduced intramolecular electron transfer (ET) is essential for understanding charge transport in biological and synthetic systems. This study examines ET in peptide His-Glu-Tyr-Gly (1) and the conjugate His-Gln(BP)-Tyr-Gly (2) with benzophenone (BP) as a photoactive electron acceptor and His or Tyr as donors. Time-resolved and field-dependent chemically induced dynamic nuclear polarization (CIDNP) techniques were employed to investigate ET mechanisms and kinetics. Peptide 1 with 3,3’,4,4’-tetracarboxy benzophenone as a photosensitizer initially forms two types of radical with radical center at either His or Tyr residue, the consequent intra- and intermolecular ET electron transfer from Tyr residue to the His radical takes place with rate constants ke(intra)=(1.5±0.5)×105 s− 1 and ke(inter)=(1.3±0.4)×107 M− 1s− 1 at pH 8.8. Conjugate 2 forms two types of biradicals under irradiation: with radical centers at Tyr and BP across the entire pH range, and with radical centers at His and BP at slightly basic pH. Field-dependent CIDNP revealed nonzero electronic exchange interaction (2Jex = − 8.78 mT) at acidic pH, indicating proximity between BP and Tyr radicals. Low-field CIDNP spectra showed strong emissive polarization patterns, with pH-dependent exchange interaction and biradical geometry. Notably, no electron transfer from tyrosine to histidine radicals was observed in the conjugate 2, distinguishing its behavior from peptide 1.

AB - Photoinduced intramolecular electron transfer (ET) is essential for understanding charge transport in biological and synthetic systems. This study examines ET in peptide His-Glu-Tyr-Gly (1) and the conjugate His-Gln(BP)-Tyr-Gly (2) with benzophenone (BP) as a photoactive electron acceptor and His or Tyr as donors. Time-resolved and field-dependent chemically induced dynamic nuclear polarization (CIDNP) techniques were employed to investigate ET mechanisms and kinetics. Peptide 1 with 3,3’,4,4’-tetracarboxy benzophenone as a photosensitizer initially forms two types of radical with radical center at either His or Tyr residue, the consequent intra- and intermolecular ET electron transfer from Tyr residue to the His radical takes place with rate constants ke(intra)=(1.5±0.5)×105 s− 1 and ke(inter)=(1.3±0.4)×107 M− 1s− 1 at pH 8.8. Conjugate 2 forms two types of biradicals under irradiation: with radical centers at Tyr and BP across the entire pH range, and with radical centers at His and BP at slightly basic pH. Field-dependent CIDNP revealed nonzero electronic exchange interaction (2Jex = − 8.78 mT) at acidic pH, indicating proximity between BP and Tyr radicals. Low-field CIDNP spectra showed strong emissive polarization patterns, with pH-dependent exchange interaction and biradical geometry. Notably, no electron transfer from tyrosine to histidine radicals was observed in the conjugate 2, distinguishing its behavior from peptide 1.

UR - https://www.mendeley.com/catalogue/241f2ff7-8350-357c-bd42-1ee04e0f193e/

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-105008530125&origin=inward&txGid=bd6c50aea16a2dc1b245493e8185f09e

U2 - 10.1038/s41598-025-04831-6

DO - 10.1038/s41598-025-04831-6

M3 - Article

C2 - 40542027

VL - 15

JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

IS - 1

M1 - 20135

ER -