Abstract:
:Normal coordinate analyses and vibrational assignments are presented for the dimethyl phosphate anion [(CH3O)2PO2-] and its deuteriomethyl [(CD3O)2PO2-] and carbon-13 [(13CH3O)2PO2-] derivatives in the gauche-gauche conformation. The dimethyl phosphate anion, which is the simplest model for the nucleic acid phosphodiester moiety, exhibits many of the spectral complexities of DNA and RNA and has previously resisted a complete and consistent vibrational analysis. In the present study we make use of new experimental data on the dimethyl phosphate isotopomers, including Raman depolarization measurements, to develop a consistent valence force field for normal modes of the C--O--P--O--C phosphodiester network and its hydrogenic substituents, as well as for stretching and bending modes of the O--P--O network of the anionic phosphodioxy group (PO2-). The force field established for dimethyl phosphate incorporates one significant nonbonded force constant, introduced from ab initio calculations, to account for interaction between the two ester C--O bonds. This study resolves previous problematic assignments for conformation-sensitive symmetric (in-phase) and asymmetric (out-of-phase) skeletal stretching modes of the ester linkages and demonstrates substantial anharmonicity in the hydrogen-stretching vibrations of the methyl substituents. New assignments are proposed for Raman bands of the phosphodioxy group, which may serve as potential indicators of structure and interaction of the DNA phosphates.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Guan Y,Wurrey CJ,Thomas GJ Jrdoi
10.1016/S0006-3495(94)80767-2subject
Has Abstractpub_date
1994-01-01 00:00:00pages
225-35issue
1eissn
0006-3495issn
1542-0086pii
S0006-3495(94)80767-2journal_volume
66pub_type
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