Re-formation of the Helical Structure of Human Serum Albumin by the Addition of Small Amounts of Sodium Dodecyl Sulfate after the Disruption of the Structure by Urea. A Comparison with Bovine Serum Albumin

Abstract

Upon the addition of small amounts of sodium dodecyl sulfate (SDS), the helicity of human serum albumin (HSA), lost in the urea denaturation, was mostly recovered. The profile of the recovery differed depending on the urea concentration. Then the urea concentrations were divided into three ranges: [1] a range below 3 M where the helicity only decreased as in the absence of urea (the helicity decreased down to 49% in the SDS solution); [2] a range between 4 and 8 M where the helicity initially increased up to 66% (this was the same as in the native state) and then sharply decreased; [3] a range above 9 M where the helicity only increased with an increase in added SDS concentration. When SDS was added prior to the urea denaturation, the same helicity was obtained at each surfactant concentration. Thus the SDS denaturation finally predominates over the urea denaturation. In the middle range, profiles of the structural change were rather complicated. The increase and decrease of helicity were accomplished below 3 mM SDS. It is worth noting that the helicity is recovered upon the addition of SDS less than 300 µM in the second range except for 8 M urea ([HSA] ) 10 µM). The helicity-recovery profile of HSA differs from that of a homologous protein, bovine serum albumin, the helicity of which recovers to some degree, but not completely. This difference might be attributed to the fact that the C-terminal helical-rod of HSA is amphiphilic, while that of bovine serum albumin is hydrophobic as a whole.

Effect of sodium dodecyl sulfate on folding and thermal stability of acid‐denatured cytochrome c: A spectroscopic approach

“…The above results suggest that the protein-surfactant structure with a high [SDS]/[cyt] ratio and high [SDS] are similar, regardless of the difference in pH. Adding SDS to urea-denatured serum albumin has been shown to disrupt the structure of BSA to an extent favorable for the interactions with surfactant ion independent of urea (Moriyama and Takeda 1999). This parallels our result for acid-denatured cyt c.…”

“…SDS is known to be a strong denaturant for many proteins even at the millimolar level (Turro et al 1995;Gelamo and Tabak 2000). However, its ability to counteract the effect of other denaturants was first reported by Duggan and Luck (1948) by addition of SDS to BSA in urea to reduce the viscosity of the solution, and addressed more recently by the thermal denaturation experiments of Moriyama (Moriyama and Takeda 1999).…”

Binding Properties of Hydrophobic Molecules to Human Serum Albumin Studied by Fluorescence Titration

“…27 However, attention should be paid to the small differences in their structures in discussing the correlation between structure and binding properties. 10,28,29 Binding of CnX to HSA Figure 2 shows the effects of CnX on the fluorescence intensity of ANS-HSA solution, in which the fluorescence intensity was plotted as a function of the total concentration of CnX, [CnX]total.…”

Anisotropy resolved multidimensional emission spectroscopy (ARMES): A new tool for protein analysis

“…This agreed with the three-step model with the expanded form being generated up to ~40 °C, the second step between 50-60 °C with the unfolding of domain II, . Page 12 of 26 followed by complete, irreversible unfolding at temperatures above ~60 °C [17,18,[48][49][50]. Comp1/2 displayed similar yet non-identical changes in normalized MCR scores, signifying the different locations of the Tyr residues contributing to each signal.…”