The mechanism by which the aqueous cosolvents guanidinium chloride and urea denature proteins is a matter of controversy. Here, we use all-atom molecular dynamics simulations to study the effect of both denaturants on the dewetting of water confined between nanoseparated hydrophobic plates. It is found that the denaturants inhibit the onset of dewetting, so that it occurs at shorter interplate ...

The affinities of a series of biologically relevant ions for a hydrated phospholipid membrane were investigated using molecular dynamics simulation. Interactions of molecular ions, such as guanidinium, tetramethylammonium, and thiocyanate with the bilayer were computationally characterized for the first time. Simulations reveal strong ion specificity. On one hand, ions like guanidinium and thio...

The effects of guanidinium salts in decreasing the renaturation rate and lowering the thermal stability of acid-soluble calf-skin collagen have been compared with those of formamide and urea. With the exception of guanidinium sulphate at higher concentrations, no qualitative differences were apparent in the effects of these perturbants, which thus differed only in molar activity. Activity varia...

Aggregated proteoglycans (70% aggregated), isolated from the Swarm rat chondrosarcoma by extraction with 4 M guanidinium chloride in the presence of protease inhibitors and purified by centrifugation in an associative cesium chloride gradient, were separated into the component parts by centrifugation in a dissociative cesium chloride gradient. The gradient was cut into five equal fractions. The...

1. Apo-superoxide dismutase was more labile toward a variety of inactivating stresses than was the holoenzyme. 2. cu++ restored catalytic activity to the apoenzyme and markedly enhanced its thermal stability but Cu++ plus Zn++ were needed to attain the stability of the native enzyme. 3. Co’-+ or Hgii were able to replace Zn++ in increasing the thermal stability of the Cu+f-repleted apoenzyme. I...

Eighty per cent of the proteoglycan of bovine nasal cartilage can be recovered in a purified preparation known as proteoglycan subunit; the preparation contains 87% chondroitin sulfate, 6% keratan sulfate, and 7% protein. The physical properties of proteoglycan subunit are not affected by exposure to 4 M guanidinium chloride, to reducing agents, or to pH 2.7. Proteoglycan subunit contains a sin...

Extracts from bovine nasal cartilage with 1 M-guanidinium chloride were fractionated by ultrafiltration. Gel chromatography of the low-molecular-weight material resolved three distinct fractions with inhibitory activity against (a) collagenases (22000 mol.wt.), (b) thiol proteinases cathepsin B and papain (13000 mol.wt.), and (c) trypsin and other serine proteinases (7000 mol.wt.).