FLEXIBILITY AND RIGIDITY OF PROTEINS AND PROTEIN-PIGMENT COMPLEXES

Proteins may be rigid or flexible to various degrees as required for optimal function. Flexibility of large parts of a protein, which rearrange or move are discussed. The author differentiates between several categories, although the boundaries between them are diffuse: flexibility of peptide segments, order-disorder transitions of spatially contiguous regions, and domain motions. The domains may be flexibly linked to allow rather unrestricted motions or the motions may be constrained to certain modes. The various categories of large-scale flexibility are illustrated with examples. (Edited author abstact)