GdnHCl

The gel-filtration step has a twofold purpose, first, to replace GdnHCl (which is not compatible with SDS-PAGE) with urea and, second, to raise the pH to 9 0 for the subsequent cleavage step... 

Koepf, E.K., Petrassi, H.M., Sudol, M., and Kelly, J.W. 1999. WW An isolated three-stranded antiparallel P-sheet domain that unfolds and refolds reversibly evidence for a structured hydrophobic cluster in urea and GdnHCl and a disordered thermal unfolded state. Protein Sci. 8 841-853. 

The sequences of synthetic peptides used to form two-stranded a-helical coiled coils with an interchain disulfide bond are shown above. The positions of the cysteine residues are indicated by the solid circles above the sequences. The peptide with a cysteine at position 2 (position a) is designated as C2a. b Line plots (a) A plot of [Gdn HCl]1/2, the transition midpoint of the denaturation profiles in the presence of Gdn HC1 (guanidinium chloride), versus the position of an interhelical disulfide bond at positions 2, 5, 9,12, 16,19,23,26,30, or 33. Open triangles denote the coiled coils with a terminal disulfide bond at either position 2 or position 33. Open squares denote the coiled coils with nonterminal disulfide bonds at position d (5,12,19, or 26). Open circles denote the coiled coils with nonterminal disulfide bonds at position a (9, 16, 23, or 30). Closed symbols denote the coiled coils without a disulfide bridge (reduced cysteine residues). The broken line indicates the [GdnHCl]1/2 of the native coiled coil. 

Another reagent used to unmask epitopes by denaturing antigens is guanidine hydrochloride (GdnHCl) (CH3N3.HCI), which is freely soluble in water and alcohol its... 

Fig. 18. (A) Schematic drawing of an antibody binding onto a patterned biotin SAM surface. (B) Diffraction scans obtained on the patterned surface (functional strip width = 42 pm, A = 100 pm, with functional lines containing 10% biotin, nonfunctional lines exposing 100% -OH groups) before (1), after (2) the anti-biotin antibody binding and after (3) the regeneration of the sensor surface by treatment with 4M GdnHCl. (C) Diffraction intensities of the 1st diffraction order versus the corresponding SPR minimum angles.

On the basis of the equilibrium unfolding curves of authentic and recombinant a-lactalbumin, the recombinant protein is remarkably less stable than the authentic one (Fig. 2.2) [22]. The transition midpoints were 3.2 and 2.7 M guanidine hydrochloride (GdnHCl) for the authentic and recombinant proteins, respectively and the difference in the stabilization free energy AAGnu,... 

Fig. 2.2. GdnHCl-induced unfolding transition curves for authentic and recombinant goat a-lactalbumin [22], The filled diamonds indicate the unfolding transition of the methionine-free recombinant protein produced by CNBr cleavage. The unfolding was carried out at 25° C in the presence of 1 mM CaCB, 50 mM NaCl, and 50 mM sodium cacodylate (pH 7.0). The transitions were monitored by CD measurements at 222 nm (circles and diamonds) and at 270 nm (triangles), and the transition curves were normalized between the native and fully unfolded baselines. The black line with symbols represents the authentic form, and the gray line with symbols represents the recombinant form. Reproduced with permission from [22]...

We therefore studied the unfolding and refolding kinetics of authentic and recombinant goat a-lactalbumin, induced by GdnHCl concentration jumps,... 

B.-L. and King, J., unpublished results). Tailspike also unfolds in cold SDS solution (4°C) and converts to an intermediate species similar to the thermal unfolding intermediate with a half time of 10 days. However the mechanism of unfolding induced by urea and GdnHCl are still unclear and currently under investigation. 

---