Stepwise reconstitution of

Tertiary and quaternary structure of FqFj 2.4.1. Stepwise reconstitution of FgFj 

The proton motive ATPase activity of FqF, was restored only after its quaternary structure was reconstituted [38]. A tripartite structure of F F, was found electron microscopically [51,85,86] (Fig. 5.7). The spheric portion (cf.. Fig. 5.2) of this structure was lost on removal of F, from FqF, by urea [51,58, and was restored on adsorption of [ Hjacetyl F, to F [85]. At the same time, the proton channel activity of Fq was converted into the proton motive ATPase activity [3]. Thus, the structure of FqF, is interpreted as that shown in Figs. 5.1 and 5.2. The Fq seems smaller than F, (Fig. 5.7) [3,51], but in some preparations, F(, is much larger than Fj [86]. Perhaps owing to the hydrophobicity of F, some lipid components may be adsorbed on F,. In fact, the aggregation of FqFj always takes place at the Fq portion (Fig. 5.7). 

Further reconstitution of F, from its subunit was possible only in TF, [38,39] and EF, [40,41]. The a/3y or afiS complexes are the essential portion of the ATPase activity [40,41,87]. The recovery of the activity was 46% of the original TF, [87]. The formation of hybrid F, s from subunits of EF, and TF, [88] suggests that subunits of the different bacteria have similar roles and structural homologies. The stability of TF, was shared in the following hybrid F, s (a) complex of a and of TF, and y of 

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