Effect of physiological concentration of urea on the conformation of human serum albumin.
We report that the presence of very low concentrations (<0.1 M) of urea, a widely used chemical denaturant, induces structure formation in the water-soluble globular protein human serum albumin (HSA) at pH 7. We have presented results suggesting an almost 8% and 5% increase in alpha-helix in the presence of 10 mM urea (U) and 20 mM monomethylurea (MMU), respectively. Far and near-UV circular dichroism studies along with tryptophan fluorescence and 1-anilino-8-naphthalenesulphonicacid (ANS) binding support our view. We hypothesize that both U and MMU, at such low concentrations, modify the solvent structure, increase the dielectric constant and consequently increase hydrophobic forces resulting in enhanced alpha-helical content. The implications of these results of the lower urea regime are significant because the physiological blood urea ranges from 2.5 to 7.5 mM.
Gull
Nuzhat
N
Department of Chemistry, Aligarh Muslim University, Aligarh-202002, India.
Sen
Priyankar
P
Kabir-Ud-Din
Khan
Rizwan Hasan
RH
D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D002942:Circular Dichroism; D005453:Fluorescence; D006801:Humans; D008782:Methylurea Compounds / Q000494:pharmacology*; D011487:Protein Conformation / Q000187:drug effects; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000187:drug effects; D012709:Serum Albumin / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D014508:Urea / Q000494:pharmacology*
D000817:Anilino Naphthalenesulfonates; D008782:Methylurea Compounds; D012709:Serum Albumin; D012997:Solvents; C027132:1-anilino-8-naphthalenesulfonate; D014508:Urea; C002352:methylurea