Mutation of interfaces in domain-swapped human betaB2-crystallin.

The superfamily of eye lens betagamma-crystallins is highly modularized, with Greek key motifs being used to form symmetric domains. Sequences of monomeric gamma-crystallins and oligomeric beta-crystallins fold into two domains that pair about a further conserved symmetric interface. Conservation of this assembly interface by domain swapping is the device adopted by family member betaB2-crystallin to form a solution dimer.

Ageing and vision: structure, stability and function of lens crystallins.

The alpha-, beta- and gamma-crystallins are the major protein components of the vertebrate eye lens, alpha-crystallin as a molecular chaperone as well as a structural protein, beta- and gamma-crystallins as structural proteins. For the lens to be able to retain life-long transparency in the absence of protein turnover, the crystallins must meet not only the requirement of solubility associated with high cellular concentration but that of longevity as well. For proteins, longevity is commonly assumed to be correlated with long-term retention of native structure, which in turn can be due to inherent thermodynamic stability, efficient capture and refolding of non-native protein by chaperones, or a combination of both.

Thermodynamic analysis of the dissociation of the aldolase tetramer substituted at one or both of the subunit interfaces.

The fructose-1,6-bis(phosphate) aldolase isologous tetramer tightly associates through two different subunit interfaces defined by its 222 symmetry. Both single- and double-interfacial mutant aldolases have a destabilized quaternary structure, but there is little effect on the catalytic activity. These enzymes are however thermolabile.

Role of entropy in protein thermostability: folding kinetics of a hyperthermophilic cold shock protein at high temperatures using 19F NMR.

We used (19)F NMR to extend the temperature range accessible to detailed kinetic and equilibrium studies of a hyperthermophilic protein. Employing an optimized incorporation strategy, the small cold shock protein from the bacterium Thermotoga maritima (TmCsp) was labeled with 5-fluorotryptophan. Although chaotropically induced unfolding transitions revealed a significant decrease in the stabilization free energy upon fluorine labeling, the protein's kinetic folding mechanism is conserved.