Solvent Perturbation of Protein Structures - A Review Study with Lectins.

Use of organic molecules as co-solvent with water, the ubiquitous biological solvent, to perturb the structure of proteins is popular in the research area of protein structure and folding. These organic co-solvents are believed to somehow mimic the environment near the cell membrane. Apart from that they induce non-native states which can be present in the protein folding pathway or those states also may be representative of the off pathway structures leading to amyloid formation, responsible for various fatal diseases.

Denaturation of bovine spleen galectin-1 in guanidine hydrochloride and fluoroalcohols: structural characterization and implications for protein folding.

Guanidine hydrochloride (GdnHCl)-induced unfolding of bovine spleen galectin-1 (Gal-1) exhibits three-state mechanism involving exclusive, structured tertiary monomer in 0.5 M GdnHCl. Gal-1 has one tryptophan residue (Trp 68) per subunit.

Localization and environment of tryptophans in different structural states of concanavalin A.

We have investigated the localization and environment of tryptophan residues in different quaternary and conformational states (tetrameric, dimeric, monomeric and unfolded) of metallized and demetallized concanavalin A (ConA) by selective chemical modification, fluorescence, and phosphorescence. ConA has four tryptophan residues (Trp 40, Trp 88, Trp 109 and Trp 182) per subunit. The pattern of oxidation by N-bromosuccinimide (NBS) shows that NBS modifies, in dimer, only Trp 182 which remains inaccessible in tetramer, two (Trp 88 along with Trp 182) in monomer, all four in unfolded form in presence of EDTA, and three (possibly Trp 40 along with Trp 88 and Trp 182) in unfolded form from native or remetallized ConA.