Contrary to a previous report, S-adenosyl-L-methionine (SAM) affords stable solutions in D2O and the 1H NMR spectrum can be determined. Comparison with the spectra of the model compounds adenosine, L-methionine and L-methionine-S-methyl sulfonium iodide allows complete assignment of the proton resonances. Coupling constants were determined by homonuclear decoupling and graphical analysis and were confined by computer simulation.
Details of the molecular conformation were determined by application of the Karplus equation and calculation of relative rotational isomer populations. Evidence indicates that the ribose ring is puckered preferentially in the C3'-exo conformation and that the C4'-C5' bond is constrained to a rotamer in which the sulfonium center is gauche to H4'. No conformational constraints were detected for the Cα-Cβ and Cβ-Cα bonds of the methionine side chain. The purine ring was shown to be oriented preferentially anti by intermolecular association studies with adenosine 5'-phosphate in the presence of MN(II).
Spectra of samples of (-)S-adenosyl-L-methionine of biological origin, differing in activity, counter ion and commercial source, have consistently revealed the presence of a small amount of the (+) sulfonium diastereomer. Arguments are presented to explain the failure of previous workers to detect (+)S-adenosyl-L-methionine in biological preparations.
| Identifer | oai:union.ndltd.org:pacific.edu/oai:scholarlycommons.pacific.edu:uop_etds-1450 |
| Date | 01 January 1979 |
| Creators | Stolowitz, Mark Lewis |
| Publisher | Scholarly Commons |
| Source Sets | University of the Pacific |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | University of the Pacific Theses and Dissertations |
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