Use of Evolutionary Factor Analysis in the Spectroelectrochemistry of Escherichia coli Sulfite Reductase Hemoprotein and a Mo/Fe/S Cluster

Authors

Robert L. Keesey, Marquette University
Michael D. Ryan, Marquette UniversityFollow

Document Type

Article

Language

eng

Format of Original

9 p.

Publication Date

5-1-1999

Publisher

American Chemical Society

Source Publication

Analytical Chemistry

Source ISSN

0003-2700

Original Item ID

doi: 10.1021/ac981079h

Abstract

The deconvolution of spectroelectrochemical data is often quite difficult if the spectra of intermediates are not known. Factor analysis, however, has been shown to be a powerful technique which can make it possible to deconvolute overlapping spectra. In this work, evolving factor analysis will be used to determine the number of intermediates and the spectra of those species for two typical spectroelectrochemical experiments:  linear scan voltammetry and chronoabsorptometry in a thin-layer cell. The first system was the reduction of E. coli sulfite reductase hemoprotein (SiR-HP). Principal factor analysis indicated that three species were present. By using evolving factor analysis, the potential regions where each of the species were present were identified, and their concentrations and spectra were determined by the use of the mass balance equation. The spectra of the one-electron (SiR-HP^1-) and two-electron (SiR-HP^2-) reduced product were compared with previous work. The second experiment was the chronoabsorptometry of Cl₂FeS₂MoS₂FeCl₂^2- in methylene chloride. This experiment indicated that five species were present during the experiment. The entire set of 61 spectra were fit by assuming that there were 4 species present during the electrolysis. The rate constant for the appearance of subsequent species fit quite well with the rate constant for the disappearance of previous species. The spectra of the intermediates and final product were obtained using evolving factor analysis and a mass balance equation. Identification of the fifth species, which was probably the initial reduction product, Cl₂FeS₂MoS₂FeCl₂^3-, was difficult due to its low concentration and the fact that it was present in the same time region as the starting material.

Comments

Accepted version. Analytical Chemistry, Vol. 71, No. 9 (May 1999): 1744–1752. DOI. © 1999 American Chemical Society. Used with permission.

Recommended Citation

Keesey, Robert L. and Ryan, Michael D., "Use of Evolutionary Factor Analysis in the Spectroelectrochemistry of Escherichia coli Sulfite Reductase Hemoprotein and a Mo/Fe/S Cluster" (1999). Chemistry Faculty Research and Publications. 475.
https://epublications.marquette.edu/chem_fac/475