Dioxygen Activation by Nonheme Diiron Enzymes: Diverse Dioxygen Adducts, High-Valent Intermediates, and Related Model Complexes

Chemical Reviews, Journal Year: 2018, Volume and Issue: 118(5), P. 2554 - 2592

Published: Feb. 5, 2018

A growing subset of metalloenzymes activates dioxygen with nonheme diiron active sites to effect substrate oxidations that range from the hydroxylation methane and desaturation fatty acids deformylation aldehydes produce alkanes six-electron oxidation aminoarenes nitroarenes in biosynthesis antibiotics. common feature their reaction mechanisms is formation O2 adducts evolve into more reactive derivatives such as diiron(II,III)-superoxo, diiron(III)-peroxo, diiron(III,IV)-oxo, diiron(IV)-oxo species, which carry out particular tasks. In this review, we survey various enzymes belonging unique by carried out. We examine nature intermediates, revealed X-ray crystallography application spectroscopic methods associated reactivity. also discuss structural electronic properties model complexes have been found mimic salient aspects these enzyme sites. Much has learned past 25 years, but key questions remain be answered.

Language: Английский

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Electronic Design Criteria for O−O Bond Formation via Metal−Oxo Complexes

Inorganic Chemistry, Journal Year: 2008, Volume and Issue: 47(6), P. 1849 - 1861

Published: March 1, 2008

Metal−oxos are critical intermediates for the management of oxygen and its activation. The reactivity metal−oxo is central to formation O−O bonds, which essential step generation. Two basic strategies bonds at active sites presented. acid–base (AB) strategy involves attack a nucleophilic species (e.g., hydroxide) on an electrophilic metal−oxo. Here, active-site designs must incorporate assembly hydroxide (or water) proximate high-valent even d electron count. For radical coupling (RC) strategy, two metal−oxos odd count needed drive coupling. This Forum Article focuses different electronic structures terminal that support AB RC design ligand scaffolds engender these structures.

Language: Английский

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Tryptophan-Accelerated Electron Flow Through Proteins

Science, Journal Year: 2008, Volume and Issue: 320(5884), P. 1760 - 1762

Published: June 26, 2008

Energy flow in biological structures often requires submillisecond charge transport over long molecular distances. Kinetics modeling suggests that charge-transfer rates can be greatly enhanced by multistep electron tunneling which redox-active amino acid side chains act as intermediate donors or acceptors. We report transient optical and infrared spectroscopic experiments quantify the extent to an intervening tryptophan residue facilitate transfer between distant metal redox centers a mutant Pseudomonas aeruginosa azurin. Cu(I) oxidation photoexcited Re(I)-diimine at position 124 on histidine(124)-glycine(123)-tryptophan(122)-methionine(121) beta strand occurs few nanoseconds, fully two orders of magnitude faster than documented for single-step 19 angstrom donor-acceptor distance.

Language: Английский

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Proton-Coupled Electron Transfer in Solution, Proteins, and Electrochemistry

The Journal of Physical Chemistry B, Journal Year: 2008, Volume and Issue: 112(45), P. 14108 - 14123

Published: Oct. 9, 2008

Recent advances in the theoretical treatment of proton-coupled electron transfer (PCET) reactions are reviewed. These play an important role a wide range biological processes, as well fuel cells, solar chemical sensors, and electrochemical devices. A unified framework has been developed to describe both sequential concerted PCET, hydrogen atom (HAT). quantitative diagnostic proposed differentiate between HAT PCET terms degree electronic nonadiabaticity, where corresponds electronically adiabatic proton nonadiabatic transfer. In cases, overall reaction is typically vibronically nonadiabatic. series rate constant expressions have derived various limits by describing transitions electron−proton vibronic states. account for solvent response effects donor−acceptor vibrational motion. The protein environment can be represented dielectric continuum or described with explicit molecular dynamics. treatments applied numerous solution proteins. Expressions heterogeneous constants current densities also model systems.

Language: Английский

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Chemistry of Personalized Solar Energy

Inorganic Chemistry, Journal Year: 2009, Volume and Issue: 48(21), P. 10001 - 10017

Published: Sept. 23, 2009

Personalized energy (PE) is a transformative idea that provides new modality for the planet's future. By providing solar to individual, an supply becomes secure and available people of both legacy nonlegacy worlds minimally contributes increase in anthropogenic level carbon dioxide. Because PE will be possible only if 24 h day, 7 days week, key enabler inexpensive storage mechanism. HY (Y = halide or OH−) splitting fuel-forming reaction sufficient density large-scale storage, but relies on chemical transformations are not understood at most basic science level. Critical among these multielectron transfers proton-coupled involve activation bonds energy-poor substrates. The chemistry three italicized areas developed, from this platform, discovery paths leading hydrohalic acid- water-splitting catalysts delineated. latter catalyst captures many functional elements photosynthesis. In doing so, highly manufacturable method has been discovered.

Language: Английский

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