Date of Award:

5-1995

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Chemistry and Biochemistry

Committee Chair(s)

Linda S. Powers (Committee Chair)

Committee

Linda S. Powers

Committee

Kay Baker

Committee

Danny Blubaugh

Abstract

Heme-substituted horseradish peroxidases and myoglobins were reconstituted from the apoenzyme using mesoheme and diacetyldeuteroheme. X-ray absorption spectroscopy was used to determine the dimensions of the active sites of these heme-substituted proteins, and were compared with those of the proto-hemeproteins. The change in the active-site structure corresponded with the electron withdrawing and donating effects of the different side chains. The oxidation-reduction potentials of Fe4+/Fe3+ couples of the heme-substituted proteins were measured at pH 7 with K2IrCl6. The oxidation-reduction potential sequence for compound I/compound II was diacetyldeutero- > proto- > meso- in horseradish peroxidase. The oxidation-reduction potential sequence for compound II/ferric was meso- > proto- > diacetyldeutero- in both HRP and myoglobin. These results indicate that the oxidation of ferric to ferryl form may be related to a radical mechanism. A net charge theory was also proposed to explain these results.

Checksum

71a51a0183e891f396d7ef185f1687b3

Share

COinS