| Autor: |
Steen IH; Department of Microbiology, University of Bergen, P. O. Box 7800, Jahnebakken 5, N-5020 Bergen, Norway., Madern D, Karlström M, Lien T, Ladenstein R, Birkeland NK |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of biological chemistry [J Biol Chem] 2001 Nov 23; Vol. 276 (47), pp. 43924-31. Date of Electronic Publication: 2001 Aug 31. |
| DOI: |
10.1074/jbc.M105999200 |
| Abstrakt: |
With the aim of gaining insight into the molecular and phylogenetic relationships of isocitrate dehydrogenase (IDH) from hyperthermophiles, we carried out a comparative study of putative IDHs identified in the genomes of the eubacterium Thermotoga maritima and the archaea Aeropyrum pernix and Pyrococcus furiosus. An optimum for activity at 90 degrees C or above was found for each IDH. PfIDH and ApIDH were the most thermostable with a melting temperature of 103.7 and 109.9 degrees C, respectively, compared with 98.3 and 98.5 degrees C for TmIDH and AfIDH, respectively. Analytical ultracentrifugation revealed a tetrameric oligomeric state for TmIDH and a homodimeric state for ApIDH and PfIDH. TmIDH and ApIDH were NADP-dependent (K(m)((NADP)) of 55.2 and 44.4 microm, respectively) whereas PfIDH was NAD-dependent (K(m)((NAD)) of 68.3 microm). These data document that TmIDH represents a novel tetrameric NADP-dependent form of IDH and that PfIDH is a homodimeric NAD-dependent IDH not previously found among the archaea. The homodimeric NADP-IDH present in A. pernix is the most common form of IDH known so far. The evolutionary relationships of ApIDH, PfIDH, and TmIDH with all of the available amino acid sequences of di- and multimeric IDHs are described and discussed. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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