Influence of Binding of Sodium Dodecyl Sulfate, All-trans-retinol, and 8-Anilino-1-naphthalenesulfonate on the High-Pressure-Induced Unfolding and Aggregation of β-Lactoglobulin B

Abstract

Bovine beta-lactoglobulin B (beta-LG) is susceptible to pressure treatment, which unfolds it, allowing thiol-catalyzed disulfide bond interchange to occur, facilitating intermolecular bonding (both noncovalent and disulfide). In the present study, beta-LG was mixed with sodium dodecyl sulfate (SDS), all-trans-retinol (retinol), or 8-anilino-1-naphthalenesulfonate (ANS) on a 1:1.1 molar basis, and aliquots were held at pressures between 50 and 800 MPa for 30 min at pH 7.2 and 20 degrees C. Polyacrylamide gel electrophoresis (PAGE) showed that beta-LG alone (control) was converted into a non-native monomer and a series of dimers, trimers, etc., at pressures beyond 100 MPa; SDS inhibited the formation of non-native species up to 200 MPa, and neither retinol nor ANS inhibited the formation of the non-native species as effectively as SDS. At pressures beyond 350 MPa, SDS ceased to have any inhibitory effect, but both ANS and retinol showed significant inhibition. The near- and far-UV CD patterns and the ANS fluorescent data were consistent with the PAGE data, but the retinol fluorescent data did not show sufficient change to interpret. The results suggested that there were three discernible structural stages. In Stage I (0.1-150 MPa), the native structure is stable; in Stage II (200-450 MPa), the native monomer is reversibly interchanging with non-native monomers and disulfide-bonded dimers; and in Stage III (>500 MPa), the free CysH in non-native monomer and dimer interacts with -S-S- bonds to produce high molecular weight aggregates of beta-LG. SDS inhibited the Stage I to Stage II transition at 200 MPa, and ANS and retinol inhibited the Stage II to Stage III transition at 600 MPa.

Pressure-Induced Unfolding and Aggregation of the Proteins in Whey Protein Concentrate Solutions

“…On the basis of earlier studies (16,17) and as discussed by Considine et al (56), it appears that, at neutral pH, -LG progressively unfolds as the pressure increases to about 300 MPa. At this pressure, there are only transient structural elements (helices, strands, and sheets) and almost no extensive structure.…”

Interactions of Milk Proteins and Volatile Flavor Compounds: Implications in the Development of Protein Foods

“…It is known that high‐pressure treatment changes the structure of milk proteins, and is thus likely to affect the protein–flavor interactions. In particular, β‐lg has been shown to be very sensitive towards pressure‐induced denaturation, and the process of pressure denaturation appears to be similar but not identical to that of heat denaturation (Huppertz and others 2004; Considine and others 2005b). α‐La is more resistant to pressure than β‐lg (Huppertz and others 2004; Liu and others 2005a).…”

“…The studies by Yang and others (2003) and Liu and others (2005a) are the only ones dealing with the influence of high‐pressure treatment on protein–flavor interactions. Nonflavor ligands, when added prior to high‐pressure treatment, have been found to inhibit the formation of intermediate, non‐native protein species (Considine and others 2005b). The same effect may exist with flavor ligands but has not been studied yet.…”

Solid–liquid equilibrium of ternary system sodium 1-naphthalenesulfonate + sodium 2-naphthalenesulfonate + water at (283.15, 303.15 and 323.15) K

“…130-14-3) is a valuable regent which is widely used in the functionalized reduced graphene oxide stabilization of silver nanoparticles [1]. Meanwhile, this is an intermediate in the manufacturing of 8-Anilino-1-naphthalenesulfonate [2] and 8-p-toluidino-1-naphthalenesulfonate [3], and in many other applications. While sodium 2-naphthalenesulfonate (CAS registry no.…”