Dataset Information

Identifying electron transfer coordinates in donor-bridge-acceptor systems using mode projection analysis.

ABSTRACT: We report upon an analysis of the vibrational modes that couple and drive the state-to-state electronic transfer branching ratios in a model donor-bridge-acceptor system consisting of a phenothiazine-based donor linked to a naphthalene-monoimide acceptor via a platinum-acetylide bridging unit. Our analysis is based upon an iterative Lanczos search algorithm that finds superpositions of vibronic modes that optimize the electron/nuclear coupling using input from excited-state quantum chemical methods. Our results indicate that the electron transfer reaction coordinates between a triplet charge-transfer state and lower lying charge-separated and localized excitonic states are dominated by asymmetric and symmetric modes of the acetylene groups on either side of the central atom in this system. In particular, we find that while a nearly symmetric mode couples both the charge-separation and charge-recombination transitions more or less equally, the coupling along an asymmetric mode is far greater suggesting that IR excitation of the acetylene modes preferentially enhances charge-recombination transition relative to charge-separation.

SUBMITTER: Yang X

PROVIDER: S-EPMC5333094 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Microbially-mediated uranium bioremediation has been demonstrated in uranium contaminated aquifers when acetate was artificially supplied and growth of the natural population of Geobacteraceae was stimulated. In order to mimic the environmental response to acetate, steady-state cells of G. sulfureducens were cultured in chemostats under conditions of either 1) acetate as the sole electron donor and limiting factor and fumarate as the sole electron acceptor or 2) acetate was supplied in excess with fumarate as sole electron acceptor and limiting factor. In silico fluxome modeling and transcriptome analysis were used as tools for investigating the cell response to the acetate availability. For global gene expression profiling, a DNA microarray of the complete G. sulfurreducens genome was used. Statistically significant results were obtained from two-color, dye swap hybridizations produced from a total of three biological replicates. Eight technical replicates were tested from two of the biological replicates and six technical replicates were tested from the third biological replicate. Major findings from this study are given as follows. The in silico model successfully predicted a higher TCA-cycle flux (ca. 2-fold) under acetate-excess conditions, suggesting that catabolism of acetate is favored with respect to anabolism, and thus more electrons are available for metal reduction. Transcriptome analyses offered a comprehensive picture of the regulation points subjected to the acetate availability. Under acetate-excess conditions, acetate transporters in the G. sulfurreducens genome were down-regulated. In addition the oxidation-related acetyl-CoA transferase was up-regulated approximately three-fold and the assimilatory-related acetate kinase was down-regulated approximately two-fold, respectively, indicating that the transcriptional regulation of acetate activation may be the key point for coping with the excess of acetate and increasing the TCA flux. The level of transcription for 10 c-type cytochromes was significantly increased in cells cultured with an excess of acetate. OmcS, an outer-membrane cytochrome which actively participates in electron transfer to Fe(III)-oxides and graphite electrodes from fuel cells, showed one of the highest fold increases in transcription. The integration of in silico modeling and genome-wide analysis shows for first time how G. sulffureducens adapts its metabolic flux and transcriptional network for optimizing the use of acetate as an electron donor for exocellular respiration instead of for use as a carbon source for biomass production. Keywords: Geobacter, gene expression, acetate limitation, fumarate limitation

Dataset Information

Identifying electron transfer coordinates in donor-bridge-acceptor systems using mode projection analysis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure