| Autor: |
M. G. Kopczynski, William H. Orme-Johnson, William W. Bachovchin, Swee Lian Tan, B. M. Babior |
| Rok vydání: |
1986 |
| Předmět: |
|
| Zdroj: |
Journal of Biological Chemistry. 261:3483-3485 |
| ISSN: |
0021-9258 |
| DOI: |
10.1016/s0021-9258(17)35673-9 |
| Popis: |
During the deamination of S-2-aminopropanol by the AdoCbl-dependent ethanolamine ammonia-lyase of Clostridia sp., a catalytic intermediate accumulates whose active site contains two paramagnetic species: cob(II)alamin and a free radical derived from the substrate molecule. Spin-echo spectroscopy has revealed that the unpaired electron on the substrate-derived radical is delocalized over a nitrogen atom that from its quadrupole splittings is probably a component of a secondary amide group. Experiments with 15N- and deuterium-labeled propanolamine gave no evidence of an interaction between this unpaired electron and the nitrogen originally attached to the substrate molecule. These results strongly suggest that the substrate-derived radical in this intermediate has already lost its nitrogen, and that this radical is stabilized by delocalization of the unpaired electron onto a nitrogen most likely situated in one of the peptide bonds of the enzyme backbone. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
