scholarly journals The Conformation of a Soluble Wool Keratin Derivative

1963 ◽  
Vol 16 (1) ◽  
pp. 231 ◽  
Author(s):  
BS Harrap
Keyword(s):  
Aqueous Solution ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Random Coil ◽  
Optical Rotatory ◽  
Upper Limit ◽  
Helical Content ◽  
Degree Of Severity ◽  
Wool Keratin

The conformation of a low-sulphur soluble wool keratin derivative (SCMKA) has been studied by optical rotatory dispersion. On the assumption that the overall conformation consists of a mixture of a-helical and random-coil regions, this protein has a helical content of about 50% in aqueous solution at pH 9�1; this helical content does not vary with the degree of severity of the preparative procedure. The protein may be reversibly converted to the random-coil form by heating to 70�0, or by treatment with urea at concentrations exceeding 6r.r. An increase in pH to 12�5 causes very little change in conformation, such change as does occur being reversible. The maximum helical content which has been induced by solvents into the protein is about 62% in 2-chloroethanol. This probably represents the upper limit of the helical content of this protein as it occurs in the fibre. The changes in the conforma. tion of the protein which occur in several other solvents are briefly discussed.

An optical rotatory dispersion study on fibrinogen and some of its derivatives

1968 ◽  
Vol 46 (6) ◽  
pp. 617-620 ◽  
Author(s):  
William D. McCubbin ◽  
Cyril M. Kay
Keyword(s):  
Tertiary Structure ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Tryptic Digestion ◽  
Optical Rotatory ◽  
Molecular Rearrangement ◽  
The Core ◽  
Helical Content ◽  
Cotton Effects ◽  
Fibrinogen Molecule

Visible and ultraviolet optical rotatory dispersion measurements were carried out on native fibrinogen and some of its derivatives. The latter include: (1) desialicized fibrinogen, (2) a large fragment of the fibrinogen molecule produced by short tryptic digestion, (3) fibrin monomer, and (4) intermediate fibrin polymers produced by the controlled thrombin proteolysis of fibrinogen. The α-helical content of native fibrinogen was deduced as 32%, and empirical calculations suggest that there is about 14% β-structure in the molecule. Sialic acid plays no significant role in the maintenance of the secondary and tertiary structure of the native molecule. No major conformational change is associated with the thrombin proteolysis of fibrinogen, although a small increase in helical content (~5%) accompanies the staggered overlap association of fibrin monomers. The "core" resulting from the controlled tryptic digestion of fibrinogen undergoes a molecular rearrangement relative to the native molecule, such that it possesses a lower α-helical content (24%) and a higher β-form value (23%). In addition, some of the additional tyrosines in the core become encompassed in regions of greater asymmetry to give rise to small aromatic Cotton effects centered around 285 mμ.

The effect of ligand binding and acid splitting on the optical rotatory dispersion of ferric horseradish peroxidase

1968 ◽  
Vol 46 (10) ◽  
pp. 1231-1235 ◽  
Author(s):  
William D. Ellis ◽  
H. Brian Dunford
Keyword(s):  
Horseradish Peroxidase ◽  
Ligand Binding ◽  
Protein Conformation ◽  
Spectral Region ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory ◽  
Helical Content ◽  
Protein Moiety ◽  
Soret Region

The optical rotatory dispersion of horseradish peroxidase and its cyanide, fluoride, and hydroxide complexes was studied in the spectral region 215–450 mμ, and that of the azide complex at 350–450 mμ. The effect that splitting the heme from the protein of peroxidase has on the optical rotatory dispersion in the 215–450 mμ region was also studied. Results of measurements of the reduced mean residue rotation at 233 mμ, lead to the conclusion that there are no significant changes in gross protein conformation upon the binding of ligands to peroxidase, but that the splitting of the heme causes a reduction of the helical content of the protein. Pure peroxidase was estimated to have 43% α-helical content, which was reduced to 33% when the heme was split from the protein. Results of studies in the Soret region indicate that the binding of various ligands does not cause an alteration of the geometry of the heme with respect to the protein moiety.

A combined experimental and theoretical study of optical rotatory dispersion for (R)-glycidyl methyl ether in aqueous solution

2019 ◽  
Vol 21 (7) ◽  
pp. 3644-3655 ◽  
Author(s):  
Franco Egidi ◽  
Tommaso Giovannini ◽  
Gianluca Del Frate ◽  
Paul M. Lemler ◽  
Patrick H. Vaccaro ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Experimental Study ◽  
Methyl Ether ◽  
Solvent Effects ◽  
Theoretical Study ◽  
Optical Rotation ◽  
Classical Model ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory

We present a theoretical-experimental study of the optical rotation of (R)-glycidylmethylether using a mixed quantum-classical model for solvent effects.

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