Membrane-induced changes in the holomyoglobin tertiary structure: interplay with function.

The effect of anionic phospholipid membranes on holomyoglobin (holoMb) conformation and deoxygenation was studied. HoloMb structural changes and behavior in the presence of membranes were monitored by a variety of techniques including far UV and near UV circular dichroism, tryptophan (Trp) fluorescence, absorbance in the Soret region, differential scanning calorimetry, (1)H-NMR spectroscopy, size exclusion chromatography, and macroscopic diffusion. Kinetics of deoxygenation was monitored by absorption at 581 nm.

[Changes in rigidity of the polymeric chain of the lambda-phage DNA in aqueous solutions with low ionic strength over the pH range 4-9.5].

It was shown that the decrease in the rigidity (persistent length) of phage lambda DNA, revealed previously by laser correlation spectroscopy, occurs in an aqueous solution at concentrations of sodium salts less than 10(-2) M in the pH range 4-9.5. DNA coils of anomalously small size (approximately twofold less than the size reported by other authors) are formed.

Molten globule-like state of cytochrome c under conditions simulating those near the membrane surface.

Methanol-induced conformational transitions in cytochrome c have been studied by near- and far-UV circular dichroism, Trp fluorescence, microcalorimetry, and diffusion measurements. The existence of at least two cooperative stages of transition has been shown. At the first stage, the native protein is transformed into an intermediate which has only traces of tertiary structure, but has a native-like secondary structure content and is relatively compact; i.

Study of the structure of streptokinase conjugates with a hydrophilic vinylpyrrolidone copolymer.

The modification of streptokinase by a synthetic N-vinylpyrrolidone copolymer leads to formation of conjugates varying in structures according to the proportions of the components in the reaction medium. Based on data obtained from spectrophotometry, as well as sedimentation and diffusion analyses, it is shown that in the presence of excess protein in the reaction medium, formation of the main chain takes place via the copolymer associated with several protein globules. Under conditions of excess modifier copolymer, either single-site and/or multiple-site bonding is possible for the protein backbone, depending on the molecular weight of the copolymer.