Journal article

Itzhaki LS, Lowe AR

153, 166

747

Ankyrins/ chemistry/metabolism Antibodies/ chemistry/metabolism Humans Kinetics Models, Molecular Nanowires/ chemistry Protein Engineering Protein Folding Protein Stability Protein Structure, Tertiary Thermodynamics

Itzhaki, Laura S Lowe, Alan R Review United States Adv Exp Med Biol. 2012;747:153-66. doi: 10.1007/978-1-4614-3229-6_10. In this chapter we review recent studies of repeat proteins, a class of proteins consisting of tandem arrays of small structural motifs that stack approximately linearly to produce elongated structures. We discuss the observation that, despite lacking the long-range tertiary interactions that are thought to be the hallmark of globular protein stability, repeat proteins can be as stable and as co-orperatively folded as their globular counterparts. The symmetry inherent in the structures of repeat arrays, however, means there can be many partly folded species (whether it be intermediates or transition states) that have similar stabilities. Consequently they do have distinct folding properties compared with globular proteins and these are manifest in their behaviour both at equilibrium and under kinetic conditions. Thus, when studying repeat proteins one appears to be probing a moving target: a relatively small perturbation, by mutation for example, can result in a shift to a different intermediate or transition state. The growing literature on these proteins illustrates how their modular architecture can be adapted to a remarkable array of biological and physical roles, both in vivo and in vitro. Further, their simple architecture makes them uniquely amenable to redesign-of their stability, folding and function-promising exciting possibilities for future research.