Fatty acid binding to bovine serum albumin prevents formation of intermediate during denaturation.
Urea-induced denaturation of defatted BSA and BSA containing six mol palmitic acid/mol protein (fatted BSA) has been studied by the techniques of UV difference spectroscopy and fluorescence spectroscopy. The notable differences between the two transitions are a shift in the transition of fatted BSA to a higher urea concentration and a three-state denaturation transition in defatted BSA compared to an apparent two-state denaturation transition in fatted BSA. The stable denaturation intermediate in defatted BSA occurs at 4.5-5.0 M urea, a urea concentration at which denaturation in fatted BSA has not yet started. These results are further supported by the difference spectral results obtained at 4.5 M urea in the two albumin preparations. The occurrence of denaturation intermediate only in defatted BSA and the presence of the two strong fatty-acid-binding sites in domain III lead us to conclude that this domain is relatively unstable in the absence of fatty acids and is responsible for the formation of intermediate.
Department of Biochemistry, Faculty of Medicine, AMU, Aligarh, India.
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Ahmad
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Qasim
D005227:Fatty Acids / Q000378:metabolism*; D011485:Protein Binding; D011489:Protein Denaturation; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D014508:Urea
D005227:Fatty Acids; D012710:Serum Albumin, Bovine; D014508:Urea