Author

Daniel Pambi

Date of Award

12-1988

Degree Type

Thesis

University or Center

Atlanta University (AU)

Degree Name

M.S.

Department

Chemistry

Abstract

The purpose of this study was to determine the protonation sites in guanosine-5'-monophosphate (5'-GMP), and to correlate the ease of protonation with the chemical nature and composition of substituent groups. The laser Raman spectra of 5'-GMP, 7-methyl-guanosine-5'-monophosphate (m7-GMP), and 8-bromoguanosine-5'-monophosphate (8-Br-GMP) at various pH and pD values were recorded with a Spex Ramalog-6 spectrometer. Based on the spectral changes observed in these studies, the preferred order of protonation sites for 5'-GMP and 8-Br-GMP is N7, 06 and N3. In the case of m7-GMP, the preferred sites are 06 and N3. The opening of the imidazole ring in m7-GMP is observed at pH value of about 9.4. It appears that the presence of the methyl group has a stabilizing effect on the protonated (keto) species. As expected, the vibrational modes of the phosphate group are unaffected by substituents on the guanine part of 5'-GMP. The complete spectra and vibrational assignments for 5'-GMP, m7- GMP and 8-Br-GMP are presented in this thesis.

Comments

Signature pages are on the file with the graduate school. An archival copy of the document is available in the Archives Research Center

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