Mechanistic Study of ROS-photogeneration by Pterin

Pteridines ◽  
2011 ◽  
Vol 22 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Hong-Fang Ji ◽  
Liang Shen
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Transfer Reaction ◽  
Direct Electron Transfer ◽  
Density Functional Theory Calculations ◽  
Electron Transfer Reaction ◽  
Mechanistic Study ◽  
Functional Theory ◽  
Direct Energy ◽  
Electronic Parameters

Abstract Pterins are widespread in biological systems and possess photosensitizing activities. In the present study, the photosensitization mechanism of acid form of pterin (PTA) and basic form of pterin (PTB) is investigated by means of density functional theory calculations. The reactive oxygen species-photogenerating pathways of the lowest triplet excited (T1) state PTA and PTB are proposed as follows. Through direct energy transfer, both T1 state PTA and PTB can photogenerate 1O2. Two possible O2 .−-generating pathways are proposed according to the electronic parameters of PTA and PTB: i) direct electron transfer from T1 state PTA and PTB to 3O2 and the electron transfer reaction is more favorable energetically for PTB in comparison with PTA; and ii) electron transfer from anion radical of PTA and PTB to 3O2.

A density functional theory based study of the electron transfer reaction at the cathode–electrolyte interface in lithium–air batteries

2015 ◽  
Vol 17 (17) ◽  
pp. 11740-11751 ◽  
Author(s):  
Saeed Kazemiabnavi ◽  
Prashanta Dutta ◽  
Soumik Banerjee
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Transfer Reaction ◽  
Reaction Rates ◽  
Electron Transfer Reaction ◽  
Oxygen Molecule ◽  
Functional Theory ◽  
Electrolyte Interface ◽  
Air Battery ◽  
Lithium Air Batteries

Electron transfer reaction at the cathode–electrolyte interface in a lithium–air battery, whereby the oxygen molecule is reduced, is modeled and the reaction rates are correlated with the structure of the cation.

scholarly journals Spectroscopic evidence for direct flavin-flavin contact in a bifurcating electron transfer flavoprotein

2020 ◽  
Vol 295 (36) ◽  
pp. 12618-12634
Author(s):  
H. Diessel Duan ◽  
Nishya Mohamed-Raseek ◽  
Anne-Frances Miller
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Protein Denaturation ◽  
Rhodopseudomonas Palustris ◽  
Density Functional Theory Calculations ◽  
Site Directed Mutagenesis ◽  
Functional Theory ◽  
Electron Transfer Flavoprotein ◽  
Midpoint Potential ◽  
Ct Complex

A remarkable charge transfer (CT) band is described in the bifurcating electron transfer flavoprotein (Bf-ETF) from Rhodopseudomonas palustris (RpaETF). RpaETF contains two FADs that play contrasting roles in electron bifurcation. The Bf-FAD accepts electrons pairwise from NADH, directs one to a lower-reduction midpoint potential (E°) carrier, and the other to the higher-E° electron transfer FAD (ET-FAD). Previous work noted that a CT band at 726 nm formed when ET-FAD was reduced and Bf-FAD was oxidized, suggesting that both flavins participate. However, existing crystal structures place them too far apart to interact directly. We present biochemical experiments addressing this conundrum and elucidating the nature of this CT species. We observed that RpaETF missing either FAD lacked the 726 nm band. Site-directed mutagenesis near either FAD produced altered yields of the CT species, supporting involvement of both flavins. The residue substitutions did not alter the absorption maximum of the signal, ruling out contributions from residue orbitals. Instead, we propose that the residue identities modulate the population of a protein conformation that brings the ET-flavin and Bf-flavin into direct contact, explaining the 726 nm band based on a CT complex of reduced ET-FAD and oxidized Bf-FAD. This is corroborated by persistence of the 726 nm species during gentle protein denaturation and simple density functional theory calculations of flavin dimers. Although such a CT complex has been demonstrated for free flavins, this is the first observation of such, to our knowledge, in an enzyme. Thus, Bf-ETFs may optimize electron transfer efficiency by enabling direct flavin-flavin contact.

Luminescence Mechanistic Study of BaLaGa3O7:Nd Using Density Functional Theory Calculations

2016 ◽  
Vol 55 (6) ◽  
pp. 2855-2863 ◽  
Author(s):  
Junling Meng ◽  
Xiaojuan Liu ◽  
Congting Sun ◽  
Chuangang Yao ◽  
Lifang Zhang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Mechanistic Study ◽  
Functional Theory

Metal carbonyl complexes of potentially ambidentate 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole acceptors

2017 ◽  
Vol 72 (11) ◽  
pp. 839-846
Author(s):  
Sebastian Plebst ◽  
Martina Bubrin ◽  
David Schweinfurth ◽  
Stanislav Záliš ◽  
Wolfgang Kaim
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Electron Transfer ◽  
Density Functional ◽  
Metal Carbonyl ◽  
Density Functional Theory Calculations ◽  
Carbonyl Complexes ◽  
Functional Theory ◽  
Metal Carbonyl Complexes ◽  
Reduced Forms

AbstractThe compounds [W(CO)5(btd)], [W(CO)5(bsd] and [Re(CO)3(bpy)(bsd)](BF4), btd=2,1,3-benzothiadiazole and bsd=2,1,3-benzoselenadiazole were isolated and characterized experimentally (crystal structure, spectroscopy, spectroelectrochemistry) and by density functional theory calculations. The results confirm single N-coordination in all cases, binding to Se was calculated to be less favorable. Studies of one-electron reduced forms indicate that the N-coordination is maintained during electron transfer.

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