ISSN:
1433-4909
Keywords:
Key words Thermophilic enzymes
;
3-Isopropylmalate dehydrogenase
;
Thermostability
;
Thermus thermophilus
;
Chimeric proteins
;
Interdomain interaction
;
Differential scanning calorimetry
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract In our previous study, we showed that a chimeric isopropylmalate dehydrogenase, 2T2M6T, between an extreme thermophile, Thermus thermophilus, and a mesophile, Bacillus subtilis, isopropylmalate dehydrogenases (the name roughly denotes the primary structure; the first 20% from the N-terminal is coded by the thermophile leuB gene, next 20% by mesophile, and the rest by the thermophile gene) denatured in two steps with a stable intermediate, suggesting that in the chimera some of the interdomain interaction was lost by amino acid substitutions in the "2M" part. To identify the residues involved in the interdomain interactions, the first and the second halves of the 2M part of the chimera were substituted with the corresponding sequence of the thermophile enzyme. Both chimeras, 3T1M6T and 2T1M7T, apparently showed one transition in the thermal denaturation without any stable intermediate state, suggesting that the cooperativity of the conformational stability was at least partly restored by the substitutions. The present study also suggested involvement of one or more basic residues in the unusual stability of the thermophile enzyme.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007920050125
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