| Autor: |
Hardy, Robert E., Dill, Kilian |
| Zdroj: |
FEBS Letters; July 1982, Vol. 143 Issue: 2 p327-331, 5p |
| Abstrakt: |
Methionine‐81 and/or ‐8 of the transmembrane sialoglycoprotein, glycophorin A, have been specifically alkylated with 13CH3I to produce the sulfonium ion derivatives [S‐[13C]methylmethionine‐8]glycophorin A and [S‐[13C]methylmethionine‐8 and ‐81]glycophorin A. 13C NMR spectra of these species show that the resonances of the methyl groups of the modified glycophorins occur at 26.1 ppm downfield from Me4Si. A spin‐lattice relaxation time of 0.4 was observed for the 13C‐enriched methyl resonances of the sulfonium ion derivatives of Met‐8 and ‐81, which corresponds to an effective correlation time of < 2× 10−10s. Demethylation of the 2 glycophorin A sulfonium ion species with 2‐mercaptoethanol produces native glycophorin A which now has the ε‐carbon of the methionine residue(s) 45% isotopically enriched. The ε‐carbon of Met‐8 was found to occur at 15.7 ppm downfield from Me4Si whereas the ε‐carbon of Met‐81 exhibited an unusual chemical shift of 2.0 ppm downfield from Me4Si. The spin‐lattice relaxation time of both resonances was found to be ∼0.3 s. |
| Databáze: |
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