Complement assembly of two fragments of the streptococcal protein G B1 domain in aqueous solution

We examined the complementation of various pairs of fragments derived from the streptococcal protein G B1 domain by NMR and CD. Most were not associated; however, one pair of fragments (1-40) and (41-56) interacted sufficiently enough to regenerated a stable 1:1 complex, Kd = 9 x 10(-6) M. A 2D-NMR analysis showed that the structure of the complex resembled that of native domain. Here we discuss the complementation from the viewpoint of the folding pathway of the protein.