PRELIMINARY STUDIES OF A METALLOPROTEIN MODEL SYSTEM.
Item
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Title
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PRELIMINARY STUDIES OF A METALLOPROTEIN MODEL SYSTEM.
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Identifier
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AAI8222971
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identifier
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8222971
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Creator
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ONADY, GARY MICHAEL.
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Contributor
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David K. Lavallee
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Date
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1982
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Inorganic
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Abstract
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Important oxidation-reduction reactions in living systems involve a series of metalloproteins which undergo electron transfer in a highly specific manner. Prosthetic group alignment with the formation of an electron transfer complex is thought to be crucial in determining electron transfer between such proteins. The distances separating prosthetic groups are therefore expected to play an important role in such electron transfer processes.;Two kinetic theories may apply to such systems: the adiabatic Marcus theory, or the nonadiabatic Hopfield theory. Both theories show distance dependence on electron transfer rates. Marcus theory, applied to systems having fixed geometry, predicts an increase in rate with separation of redox centers of the same sign of charge due to favorable electrostatic effects on the outer-sphere activation energy. Hopfield theory predicts an opposite effect for distance dependence on electron transfer rates due to decreased value of the overlap integral between the two wave functions of the redox centers.;The purpose of this project is to investigate electron transfer.;properties of systems where redox centers are separated by.;known distances. Androstane and cholestane derivatives were.;used to separate Ru('2+) and Co('3+) reaction centers. Complexes.;investigated were {lcub}(pic)(NH(,3))(,4)Ru(3,7dac)Co(NH(,3))(,4)(H(,2)O){rcub}('5+) and.;{lcub}(pic)(NH(,3))(,4)Ru(3,7daa)Co(NH(,3))(,4)(H(,2)O){rcub}('5+) in which metal centers are separated by 7.47 and 13.36 A respectively. Electron transfer rates were observed as identical for both cases with k = 1.4 x 10('-4) s('-1). Activation parameters are nearly identical where (DELTA)H= = 22 kcal/mole and (DELTA)S= = -5 cal/mole K. Further experiments will be necessary to verify the mechanism of electron transfer observed in the androstane and cholestane derivatives.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
