Myeloperoxidase and eosinophil peroxidase have been isolated from outdated human blood. Peroxidase activity was extracted from washed leucocytes using 0.5 M-CaCl2 and the extract further purified by chromatography on concanavalin A--Sepharose, phenyl-Sepharose and finally by gel filtration. The final enzyme preparations were highly purified according to spectral and gel-electrophoretic criteria...

sis usually involve chaotropic agents such as guanidinium chloride and (or) detergents for the dissociation of iron at an acidic pH from transferrin. Reduction is achieved with various reducing compounds such as ascorbic acid, hydroxylamine, thioglycolic acid, and others. Among these, ascorbic acid is unique in its property not only to reduce but also to chelate iron. This property appears to b...

Excimer-forming cysteines in tubulin are detected by the presence of excimer fluorescence in N-(1-pyrenyl)maleimide-labeled tubulin. The ratio of excimer/monomer fluorescence of labeled protein remained unchanged upon its dilution. These results indicating that both partner of each pair(s) of cysteine are located in the same subunit. The excimer fluorescence is insensitive to prior treatment of...

By using CsCl-density-gradient ultracentrifugation, two high-Mr mucin species were isolated from human whole saliva, having buoyant densities in 0.2 M-guanidinium chloride of approx. 1.56 g/ml (pool IA) and 1.48 g/ml (pool IIA). Analytical density-gradient centrifugation of submandibular, sublingual, labial and palatal saliva, followed by immunochemical analysis with anti-mucin monoclonal antib...

Protein stability often is studied in vitro through the use of urea and guanidinium chloride, chemical cosolvents that disrupt protein native structure. Much controversy still surrounds the underlying mechanism by which these molecules denature proteins. Here we review current thinking on various aspects of chemical denaturation. We begin by discussing classic models of protein folding and how ...

The protein-keratan sulfate core of bovine nasal cartilage proteoglycan was purified by affinity chromatography on a column of immobilized hyaluronic acid. The hyaluronic acid was immobilized by reaction with a hydrazido-alkyl derivative of Sepharose in the presence of borohydride. Proteoglycan was digested with chondroitinase ABC and the entire mixture was passed over a column of the Sepharose...

For the first time, the enzyme rhodanese has been refolded after denaturation in guanidinium chloride (GdmHCl). Renaturation was by either (a) direct dilution into the assay, (b) intermediate dilution into buffer, or (c) dialysis followed by concentration and centrifugation. Method (c) preferentially retained active enzyme whose specific activity was 1140 IU/mg, which fell to 898 IU/mg after 6 ...

Urea and GdmCl are widely used to denature proteins at high concentrations. Here, we used MD simulations to study the denaturation mechanisms of helical peptide in different concentrations of GdmCl and urea. It was found that the helical structure of the peptide in water simulation is disappeared after 5 ns while the helicity of the peptide is disappeared after 70 ns in 2 M urea and 25 ns in 1 ...

Viscosity measurements in 6 M guanidinium chloride (Gdm.Cl) (pH 5.2, 25”) suggest that Kunitz soybean trypsin inhibitor (STI) undergoes a slow unfolding which requires over 2 weeks to reach completion. The reduced viscosity increased during this time from an initial value of 3.5 ml/g to a final value of 16 to 17 ml/g. At pH 7 and 25”, over 4 weeks were required to reach the same final state. Ge...

The effects of chloride and sulfate salts of tetrapropylammonium (TPA(+)) and guanidinium (Gdm(+)) on the conformational stabilities of tryptophan zipper (trpzip) and α-helical (alahel) peptides were measured by circular dichroism spectroscopy. Like Gdm(+), TPA(+) interacts with the planar tryptophan indole group, perturbing the conformational stability of trpzip peptides. TPA(+) effects are la...