Comparison in physicochemical and biochemical characteristics between the recombinant proteins which we made from fragmented subdomains and wild-type protein, acetate-CoA ligase in a hyperthermophilic archaeon, consisting of two distinct subunits (α1-2-3 and βa-b-c) provided a clue to the mystery of its molecular evolutionary passage.  Although solubility and thermostability of each fragmented subdomain turned out to be lower than that of wild-type, mixture of the three synthetic subunits of α1-2, α3, and βa-b-c had quaternary structure, thermostability, and enzymatic activity comparable to those of the wild-type.  This suggests that substantial independence and mobility of subdomain 3 have enabled rearrangement of the subdomains; and thermostability of the subdomains has constrained the composition of the subunits.
THERM