Publications by authors named "Michael Aaron"

4 Publications

  • Page 1 of 1

The Truth: An Uncomfortable Book About Relationships.

Authors:
Michael Aaron

J Sex Marital Ther 2016 Nov;42(8):749-751

a Private Practice New York , New York , USA.

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http://dx.doi.org/10.1080/0092623X.2016.1234291DOI Listing
November 2016

Catalytic reduction of dioxygen with modified Thermus thermophilus cytochrome c552.

J Inorg Biochem 2016 Apr 20;157:8-14. Epub 2016 Jan 20.

Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. Electronic address:

Efficient catalysis of the oxygen reduction reaction (ORR) is of central importance to function in fuel cells. Metalloproteins, such as laccase (Cu) or cytochrome c oxidase (Cu/Fe-heme) carry out the 4H(+)/4e(-) reduction quite efficiently, but using large, complex protein frameworks. Smaller heme proteins also can carry out ORR, but less efficiently. To gain greater insight into features that promote efficient ORR, we expressed, characterized, and investigated the electrochemical behavior of six new mutants of cytochrome c552 from Thermus thermophilus: V49S/M69A, V49T/M69A, L29D/V49S/M69A, P27A/P28A/L29D/V49S/M69A, and P27A/P28A/L29D/V49T/M69A. Mutation to V49 causes only minor shifts to Fe(III/II) reduction potentials (E°'), but introduction of Ser provides a hydrogen bond donor that slightly enhances oxygen reduction activity. Mutation of L29 to D induces small shifts in heme optical spectra, but not to E°' (within experimental error). Replacement of P27 and P28 with A in both positions induces a -50 mV shift in E°', again with small changes to the optical spectra. Both the optical spectra and reduction potentials have signatures consistent with peroxidase enzymes. The V49S and V49T mutations have the largest impact of ORR catalysis, suggesting that increased electron density at the Fe site does not improve O2 reduction chemistry.
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http://dx.doi.org/10.1016/j.jinorgbio.2016.01.023DOI Listing
April 2016

Electrocatalytic Dioxygen Reduction by Carbon Electrodes Noncovalently Modified with Iron Porphyrin Complexes: Enhancements from a Single Proton Relay.

Chemistry 2015 Dec 28;21(50):18072-5. Epub 2015 Oct 28.

Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby BC V5A1S6 (Canada).

Oxygen reduction in acidic aqueous solution mediated by a series of asymmetric iron (III)-tetra(aryl)porphyrins adsorbed to basal- and edge- plane graphite electrodes is investigated. The asymmetric iron porphyrin systems bear phenyl groups at three meso positions and either a 2-pyridyl, a 2-benzoic acid, or a 2-hydroxyphenyl group at the remaining meso position. The presence of the three unmodified phenyl groups makes the compounds insoluble in water, enabling catalyst retention during electrochemical experiments. Resonance Raman data demonstrate that catalyst layers are maintained, but can undergo modification after prolonged catalysis in the presence of O2 . The introduction of a single proton relay group at the fourth meso position makes the asymmetric iron porphyrins markedly more robust catalysts; these molecules support higher sustained current densities than the parent iron tetraphenylporphyrin. Iron porphyrins bearing a 2-pyridyl group are the most active catalysts and operate at stable current densities ≥1 mA cm(-2) for over 5 h. Comparative analysis of the catalysts with different proton relays also is reported.
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http://dx.doi.org/10.1002/chem.201502618DOI Listing
December 2015

The Emperor's New Groove.

Authors:
Michael Aaron

J Okla State Med Assoc 2004 Apr;97(4):169

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April 2004
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