| Autor: |
Krouwer JS, Holmquist B, Kipnes RS, Babior BM |
| Jazyk: |
angličtina |
| Zdroj: |
Biochimica et biophysica acta [Biochim Biophys Acta] 1980 Mar 14; Vol. 612 (1), pp. 153-9. |
| DOI: |
10.1016/0005-2744(80)90288-0 |
| Abstrakt: |
Previous work has shown that the interaction between ethanolamine ammonia-lyase (ethanolamine ammonia-lyase, EC 4.3.1.7) and adenosylcobalamin weakens the C-Co bond of the cofactor with respect to homolytic cleavage. To obtain information concerning the mechanism by which this is accomplished, a study was conducted in which optical and circular dichroism spectroscopy were used to explore the interaction between ethanoloamine ammonia-lyase and a series of adenosylcobalamin analogs composed of an adenyl residue attached to the cobalt atom of cobalamin by a methylene chain whose length varies from 2 to 6 carbons. These studies indicated that the binding of a cobalamin to the active site activates forces which tend to alter the conformation of the enzyme, and with it that of the corrin ring, but that these conformational changes are blocked by bulky Co-beta substituents which restrict corrin ring flexibility. We postulate that at least one element of the force which weakens the C-Co bond of the enzyme-bound cofactor is the relief of conformational strain which occurs when C-Co bond cleavage, by releasing the interfering adenosyl group, permits the enzyme and the corrin ring to assume the energetically favored conformation. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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