title: Guanidine hydrochloride induced reversible dissociation and denaturation of duck delta2-crystallin.
abstract: The tetrameric delta2-crystallin from duck lens exhibits a reversible dissociation-denaturation process in solutions containing guanidine hydrochloride (GdnHCl). Sigmoidal or biphasic curves for the dissociation/denaturation processes, obtained using different methods of structural analysis, as a function of GdnHCl concentration were not coincidental with each other. delta2-crystallin in 0.91 M GdnHCl existed primarily as a monomer, which had no endogenous argininosuccinate lyase activity. After dilution of the GdnHCl-treated protein, the monomers reassociated into tetramers with concomitant recovery of enzyme activity. The sigmoidal recovery of enzyme activity demonstrates a cooperative hysteretic reactivation process. When the concentration of GdnHCl was higher than 1.2 M, various partially unfolded soluble forms of delta2-crystallin were produced from the dissociated monomers as shown by size-exclusion chromatography. The formation of a partially unfolded intermediate during the dissociation-denaturation process is proposed.
authors.affiliation: Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan. hjlee@ndmctsgh.edu.tw
authors.forename: H J
authors.initials: HJ
authors.lastname: Lee
authors.forename: G G
authors.initials: GG
authors.lastname: Chang
mesh_terms: D000818:Animals; D001123:Argininosuccinate Lyase / Q000378:metabolism; D002942:Circular Dichroism; D003459:Crystallins / Q000737:chemistry*; D004372:Ducks; D005453:Fluorescence; D019791:Guanidine / Q000494:pharmacology*; D008970:Molecular Weight; D011189:Potassium Chloride / Q000494:pharmacology; D011487:Protein Conformation; D011489:Protein Denaturation
chemical_list: D003459:Crystallins; D011189:Potassium Chloride; D001123:Argininosuccinate Lyase; D019791:Guanidine