title: Reversible association of the equilibrium unfolding intermediate of lambda Cro repressor.
abstract: An extended differentiated scanning calorimetry study of the wild-type Cro repressor and of its V55C mutant has revealed a significant concentration dependence of the melting profiles, even though the two polypeptide chains forming the active repressor molecule are covalently bound within the mutant. An analysis of the temperature dependencies of the partial molar heat capacity suggests that in both cases equilibrium unfolding occurs via a highly-populated intermediate state corresponding to polypeptide tetramers. The results of thermodynamic analysis are confirmed by direct glutaraldehyde cross-linking experiments. Judging by heat effects and circular dichroism data, this intermediate state regains about 50% of the ordered structure and melts co-operatively.
authors.affiliation: Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
authors.forename: V V
authors.initials: VV
authors.lastname: Filimonov
authors.forename: V V
authors.initials: VV
authors.lastname: Rogov
mesh_terms: D010582:Bacteriophage lambda / Q000378:metabolism; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D004268:DNA-Binding Proteins; D005976:Glutaral; D007700:Kinetics; D046911:Macromolecular Substances; D008433:Mathematics; D008961:Models, Structural; D008962:Models, Theoretical; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism; D012984:Software; D013816:Thermodynamics; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D005976:Glutaral