[Carbonic anhydrase B interactions with water and urea].
Carbonic anhydrase B unfolding with urea (pH 5.7, T = 298 K) was studied by high-resolution NMR spectroscopy. The effectiveness of spin-diffusion influencing compactness of the protein molecule can be described with the rigidity parameter G. Parameter G displays sigma-like characteristic behavior when concentration increases. The ratio between integral intensities of urea and protein signals in spin-diffusion and normal 1D spectra are the same. This suggests that there is no predominant urea-protein molecular interaction. The concentration of large protein-solvent associates increases rapidly at urea levels of 4.2-6.2 M implying that protein molecule shifts to a molten globule state. Protein-solvent associates are dissipating with urea concentration increase to above 6.6 M when carbonic anhydrase B polypeptide chain is completely unfolded.
D A
DA
Prokhorov
V P
VP
Kutyshenko
V S
VS
Khristoforov
D000818:Animals; D024401:Carbonic Anhydrase I / Q000737:chemistry*; D002417:Cattle; D011489:Protein Denaturation; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D014867:Water; D014508:Urea; D024401:Carbonic Anhydrase I