Convenient Asymmetric Unit for Construction of Multi-subunit Models

Abstract

THE striking symmetry of the arrangement of protein subunits in multi-subunit enzymes and in viruses has been amply demonstrated in recent years¹. Caspar^2,3 pointed out that symmetry is to be expected in any self-assembling system stabilized by multiple weak interactions (that is, where the final structure is thermodynamically determined) and that it merely ensures the formation of the maximum number of stable bonds between identical units. The possible functional significance of such symmetrical arrangements has been considered in detail by Monod, Wyman and Changeux⁴ in their provocative interpretation of allosteric effects and cooperative binding.