shape-shifting antibodies? - (Dec/10/2007 )
Look into Catalytic antibodies. They change shape upon binding...
if u r asking for adaptable antibodies, that means u need far sofisticated immnune system which ignore affinity maturation. In that case, the antigen selection criteria includes only the antibodies which possess a range of affinities with a range of changing charges in the Fab fragment (for example like a buffer, so i wud name them as BUFFER ANTIBODIES). if vertibrates are evolved to generate so called buffering antibodies then they must demonstrate a super immune system (assumption) where self antigens could escape the adaptive antibody (buffer Ab) attack. That kind of system may not be feasible in the body as evidenced by the evolution.
Moreover, in my opinion buffer antibody system does not explain completely the evolution of animal kingdom from a single cell.
i was thinking about this assumption in agreement with medfenko and ceri.
welcome for comments