TY - JOUR

T1 - Aggregation of α-crystallins in kynurenic acid-sensitized UVA photolysis under anaerobic conditions

AU - Sherin, P. S.

AU - Zelentsova, E. A.

AU - Sormacheva, E. D.

AU - Yanshole, V. V.

AU - Duzhak, T. G.

AU - Tsentalovich, Yu P.

N1 - Funding Information: This work was supported by the Russian Scientific Foundation (grant no. 14-14-00056). The MS measurements were performed with the financial support from the Russian Foundation for Basic Research (Project no. 14-03-31189 and 14-03-00027) and the grant from the President of Russian Federation (Project MK-5367.2015.3). The authors thank Dr Sergey V. Kulemzin (Institute of Molecular and Cell Biology, Novosibirsk, Russia) for help with the crystallin separation. Publisher Copyright: © the Owner Societies 2016.

PY - 2016/4/7

Y1 - 2016/4/7

N2 - The reactions of photoexcited kynurenic acid (KNA) with bovine α-crystallins under anaerobic conditions proceed via the electron transfer from tryptophan (Trp) and tyrosine (Tyr) residues to the triplet KNA molecules. The subsequent radical reactions lead to the protein aggregation and insolubilization. The absorption of the photolyzed proteins at 335 nm as well as their total fluorescence significantly increases, while the tryptophan-related fluorescence decreases. It has been established that the alterations of the protein optical properties are related to the modifications of Trp residues. Intrinsic lens antioxidants ascorbate (Asc) and glutathione (GSH) that are present in the human lens at the millimolar level effectively block the formation of the observed light-induced protein modifications. The protective effect of Asc was attributed to its ability to quench highly reactive triplet states, while the role of GSH, most likely, corresponds to the reduction of photochemically formed radicals into a diamagnetic state. The results obtained disclose the possible mechanism of UVA-induced modifications of the lens crystallins, leading to the formation of cataract, and the role of major lens antioxidants Asc and GSH in the protection of the lens proteins.

AB - The reactions of photoexcited kynurenic acid (KNA) with bovine α-crystallins under anaerobic conditions proceed via the electron transfer from tryptophan (Trp) and tyrosine (Tyr) residues to the triplet KNA molecules. The subsequent radical reactions lead to the protein aggregation and insolubilization. The absorption of the photolyzed proteins at 335 nm as well as their total fluorescence significantly increases, while the tryptophan-related fluorescence decreases. It has been established that the alterations of the protein optical properties are related to the modifications of Trp residues. Intrinsic lens antioxidants ascorbate (Asc) and glutathione (GSH) that are present in the human lens at the millimolar level effectively block the formation of the observed light-induced protein modifications. The protective effect of Asc was attributed to its ability to quench highly reactive triplet states, while the role of GSH, most likely, corresponds to the reduction of photochemically formed radicals into a diamagnetic state. The results obtained disclose the possible mechanism of UVA-induced modifications of the lens crystallins, leading to the formation of cataract, and the role of major lens antioxidants Asc and GSH in the protection of the lens proteins.

UR - http://www.scopus.com/inward/record.url?scp=84962116006&partnerID=8YFLogxK

U2 - 10.1039/c5cp06693j

DO - 10.1039/c5cp06693j

M3 - Article

C2 - 26750082

AN - SCOPUS:84962116006

VL - 18

SP - 8827

EP - 8839

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 13

ER -