Association of the 17-kDa extrinsic protein with photosystem II in higher plants.

The structural association of the spinach 17-kDa extrinsic protein of photosystem II with other extrinsic and membrane-bound components of the photosystem was investigated by labeling the 17-kDa extrinsic protein with the amino-group-specific reagent N-hydroxysuccinimidobiotin both on intact photosystem II membranes or as a free protein in solution. After isolation of the biotinylated molecules, the modified 17-kDa proteins were allowed to rebind to photosystem II membranes which were depleted of the 17-kDa component. Differential binding of the protein biotinylated in solution compared to unmodified 17-kDa protein or 17-kDa protein modified on PS II membranes was observed.

Lethal mutagens: broad-spectrum antivirals with limited potential for development of resistance?

RNA virus populations display extreme sequence variation. It is thought that this heterogeneity is advantageous to the population, permitting adaptation to rapidly changing environments that present varying types and degrees of selective pressure. A consequence of this efficient evolution of RNA viruses is the susceptibility of these viruses to compounds that further increase sequence variation as these agents force the virus into error catastrophe.