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.

Some features of the optical rotatory dispersion spectrum of the α-lytic protease of Sorangium sp.

1969 ◽  
Vol 47 (3) ◽  
pp. 317-321 ◽  
Author(s):  
G. M. Paterson ◽  
D. R. Whitaker
Keyword(s):  
Optical Rotation ◽  
Substrate Binding ◽  
Cotton Effect ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Kinetic Properties ◽  
Optical Rotatory ◽  
Cotton Effects ◽  
Ph Dependent

A study of the kinetic properties of the α-lytic protease of Sorangium sp. indicated that substrate-binding by the enzyme was not pH dependent. In agreement with this indication of a pH-insensitive conformation, the optical rotation of the enzyme between pH 5 and 10.5 is not pH dependent. The optical rotatory dispersion spectrum above 220 mμ shows a main Cotton effect with a trough at 230 mμ and small but well-marked Cotton effects between 260 and 300 mμ. The reduced, mean residue rotation at the trough of the main Cotton effect was estimated to be −1650 ± 80° cm2/dmole; the Moffitt–Yang parameter b0 for rotations above 325 mμ is approximately zero. These values suggest that the enzyme has virtually no α-helices.

CONFORMATIONAL STUDIES ON SYNTHETIC POLY-α-AMINO ACIDS: THE HELICAL SENSE OF POLY-L-TRYPTOPHAN: OPTICAL ROTATORY DISPERSION STUDIES

1965 ◽  
Vol 43 (5) ◽  
pp. 1588-1598 ◽  
Author(s):  
Gerald D. Fasman ◽  
Margarete Landsberg ◽  
Manuel Buchwald
Keyword(s):  
Wavelength Range ◽  
Cotton Effect ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Helical Conformation ◽  
Optical Rotatory ◽  
Negative Cotton Effect ◽  
Cotton Effects ◽  
The Right ◽  
Tryptophanyl Residue

The synthesis of high molecular weight (100 000 to 200 000) polymers and copolymers of L-tryptophan and γ-benzyl-L-glutamate is reported. The optical rotatory dispersion (o.r.d.) of these polypeptides is recorded in the wavelength range 540–320 mμ and the b0 values of the Moffitt equation, using λ0 = 212ν, are listed. Poly-L-tryptophan has a b0 value of +570 in dimethylformamide (DMF). A linear relationship exists between this value, b0 values of copolymers of various ratios of L-tryptophan and γ-benzyl-L-glutamate, and the value of− 670 found for poly-γ-benzyl-L-glutamate. The o.r.d. curve of a poly-L-tryptophan film, in the 330–200 mμ wavelength range, reveals two positive Cotton effects in the 270–290 mμ region and a large negative Cotton effect at 233 mμ. Thus, despite the positive b0 value, these data prove that poly-L-tryptophan, in DMF, has the right-handed helical conformation. Hypochromicity was found for the tryptophanyl residue in the helical polypeptide. The rotatory contribution of chromophores, such as tryptophan or coenzymes, when bound asymmetrically to a protein, can be very significant, and caution is advised in the interpretation of such o.r.d. curves.

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.

A Study of the Pfeiffer Effect in Systems containing Trisoxalatometallate(III) Complexes and Cinchonine Hydrochloride

1971 ◽  
Vol 49 (12) ◽  
pp. 2161-2165 ◽  
Author(s):  
K. T. Kan ◽  
D. G. Brewer
Keyword(s):  
Dispersion Curves ◽  
Active Species ◽  
Optically Active ◽  
The Other ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory ◽  
Cotton Effects ◽  
Equilibrium Shift ◽  
Complex Ion

The Pfeiffer effect was studied in systems containing cinchonine hydrochloride and trisoxalatometallate(III) complexes of Al, Fe, Cr, Co, and Ir. The Pfeiffer rotatory dispersion curves of the Cr and Co complexes show Cotton effects analogous to that observed in the optical rotatory dispersion (o.r.d.) curves of the respective complexes. The source of the Pfeiffer effect in all these systems is attributed either to an association between the complex ion and the optically active species in solution alone, as in the case of the Ir(lII) complex, or to a combination of this association and an "equilibrium shift" between the two enantiomers in solution in favor of one of them, as in the case of the other complexes under investigation.

Ultraviolet Absorption and Optical Rotatory Dispersion Studies of Deoxyribonucleic Acid and Nucleohistone

1972 ◽  
Vol 27 (12) ◽  
pp. 1516-1528 ◽  
Author(s):  
S. Basu
Keyword(s):  
Complete Removal ◽  
Ultraviolet Absorption ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory ◽  
Absorption Region ◽  
Similar Information ◽  
Cotton Effects ◽  
Dna Protein Interaction ◽  
Second Peak

This report concerns the ultraviolet absorption and optical rotatory dispersion (ORD) of DNA and of nucleotides down to 185 mμ. An absorption band (y) at about 195 mμ occurs for all these compounds. Similar studies have been made on histones and nucleohistone. These indicate a strong absorption below 200 mμ due to protein. Consequently, if any native DNA is associated with some amount (2 - 12%) of protein (e.g., histones), the molecular absorption of DNA in the said region becomes masked, and no clear y-maximum due to DNA occurs in the absorption spectrum. The absorption of DNA in the y-band region (ca. 190 mμ) seems to be decreased as a result of DNA-protein interaction. No significant change is observed in the absorption region of DNA at longer wavelengths (250-290 mμ). The y-peak of DNA appears at about 190 mμ on complete removal of proteins. This peak is sharper than the conventional one (x) at 260 mμ and is hyperchromic on denaturation, and involves multiple Cotton effects to any degrees similar to that observed at the second peak (260 mμ).The absorption (also ORD) features of nucleohistone at the x and y wavelengths do not provide similar information (e.g., denaturation artefacts) regarding the structure of the nucleohistone contained DNA which is apparently distinct from the structures of native and partially denatured (denaturation 10%) DNA. The weaker π-π* transition (190 mμ) in the DNA bases is very susceptible to nucleoprotein interaction. This result has been used to explain the influence of nucleoprotein interaction on the configuration of DNA in nucleohistone

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