| Autor: |
Tan, G O, Ensign, S A, Ciurli, S, Scott, M J, Hedman, B, Holm, R H, Ludden, P W, Korszun, Z R, Stephens, P J, Hodgson, K O |
| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; May 1992, Vol. 89 Issue: 10 p4427-4431, 5p |
| Abstrakt: |
The nickel/iron/sulfur center of the carbon monoxide dehydrogenase (carbon monoxide:(acceptor)oxidoreductase; EC 1.2.99.2) enzyme from Rhodospirillum rubrum (Rr-CODH) was studied by x-ray absorption spectroscopy at the Ni K edge. Extended x-ray absorption fine structure data show that the first Ni coordination shell consists of 2 S atoms at 2.23 A and 2-3 N/O atoms at 1.87 A. The edge structure indicates a distorted tetrahedral or five-coordinate Ni environment in both oxidized and reduced Rr-CODH. By comparing second-shell extended x-ray absorption fine structure data of Rr-CODH to that of (Et4N)3[NiFe3S4(SEt)4], a cubane-type cluster, it was clearly established that Ni in the Rr-CODH center is not involved in the core of a NiFe3S4 cubane cluster. One model consistent with the results is a mononuclear Ni2+ site, bridged by S-Cys or sulfide to one or both of the Fe4S4 clusters of the enzyme, with the remaining coordination sites occupied by additional S-Cys or N/O-liganding amino acid residues. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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