Optical Rotatory Dispersion, Circular Dichroism, and the Pfeiffer Effect in Coordination Compounds

Optical rotatory dispersion and circular dichroism properties of yeast mitochondrial DNA's

Etude comparative de la dispersion rotatoire optique et du dichroïsme circulaire en chimie organique

An analysis of optical rotatory dispersion and circular dichroism of RNA is described which leads to an estimate of the degree of base pairing. By the use of new standards for the double‐helical parts of the molecule, based on data for two‐stranded viral RNA species, a good fit between calculated and observed curves can be achieved. Where data are available the results of analyses of optical rotatory dispersion and circular dichroism in general show satisfactory consistency.

At neutral pH, the circular dichroism (CD) and optical rotatory dispersion (ORD) of α-crystallin between 200 and 590 mµ are characteristic of the β conformation. The Moffitt parameter b0 value obtained from the ORD between 313 and 589 mµ also indicates the absence of α-helix. Most of the data suggest that the β form may represent from 35 to 63% of the protein polypeptide chain with the remainder in random conformation. α-Crystallin deaggregates to an Mw of approximately 7 x 104 when the pH is raised from 8 to 11.7 (1). The corresponding CD and ORD indicate an increase in random structure as well as the appearance of approximately 5% α-helix. Reaggregation occurs when the pH is returned to pH 8.0 (1). The 216 mµ CD negative band of the β structure reappears and the ORD spectra are also similar to the original preparations although certain small irreversible changes were noted.

Inhibition of polymerization of tobacco mosaic virus protein by modification of carboxyl groups

3 - Optical Rotatory Dispersion and Circular Dichroism in Organic Chemistry

For a small peptide, bradykinin has an unusually large percentage of proline residues in its primary structure. The occurrence of proline in a peptide chain tends to restrict the conformational flexibility of the peptide (1). Bradykinin would therefore be expected to show some degree of ordered structure in solution. Early optical rotatory dispersion (ORD) and circular dichroism (CD) results (2,3), however, suggested that the structure was freely flexible in aqueous solution. Later CD measurements on bradykinin and some of its homologs in aqueous and non-aqueous solvents (4) were interpreted as showing partial intramolecular hydrogenbonding. An 8 → 6 hydrogen-bond across proline7 was postulated for bradykinin in aqueous solution, while additional 9 → 7 and 4 → 2 hydrogen-bonds across phenylalanine8 and proline3 respectively were postulated in dioxane solution. The model on which Cann’s conclusions are based is an intramolecularly hydrogen-bonded proline derivative in non-aqueous solvents. In non-aqueous solvents the possibility of other intramolecular interactions and solvent interaction with the peptide is minimized. It seems likely therefore, that the model for bradykinin in aqueous solution would be complicated by the possible interactions described above.

Conformation-directing interactions between poly(L- or poly(D-glutamic acid)) (PLG or PDG) and poly-L-lysine (PLL) in aqueous media were investigated as functions of pH by using the optical rotatory dispersion and circular dichroism spectroscopies. The results indicate that at pH <4 PLL molecules surround the core of the right-handed α-helix of PLG, and at pH about 7, the polyelectrolyte complex formed may be in a scramble-salt form, whereas at pH >8, complexes of PLG—PLL are in a form close to β-structure. On the other hand, with PDG—PLL systems, in the low pH region, the left-handed α-helical structure of PDG is markedly disrupted by the presence of PLL, and in the high pH region, the complexes may be in a form of a scramble-salt aggregate composed of β-structures.

P. M. Scopes, Annu. Rep. Prog. Chem., Sect. B: Org. Chem., 1969, 66, 34 DOI: 10.1039/OC9696600034

A brief survey of some recent work in protein chemistry

Surveys of many of the techniques in nucleic acid chemistry are found in some recent review articles (1–6). A new book by Haschemeyer and Haschemeyer (7) is an excellent text for nearly all the biophysical techniques. In this chapter, we deal briefly with four techniques that have found rather widespread use in recent years: 1. Optical activity [optical rotatory dispersion (ORD) and circular dichroism (CD)] 2. Nuclear magnetic resonance (NMR) 3. Ultracentrifugation 4. Fiber X-ray diffraction

C.d. and o.r.d. data are reported for biotin, biotin methyl ester, and thiobiotin. The results can be analysed in terms of the c.d. and o.r.d. curves of related compounds containing the thioether and ureide (or thioureide) chromophores only.

The Molecular Basis of Optical Activity: Optical Rotatory Dispersion and Circular Dichroism. By E. Charney. Pp.376. (Wiley: New york and chichester, UK, 1979.) £18.30, $39.90.

On the isolation and conformation of bovine β-casein A 1

The conformational change of the 11S component of soybean proteins in acid was measured by ultraviolet difference spectra, optical rotatory dispersion and circular dichroism. Below pH 4, the change of tertiary structure that the tyrosine residues were exposed and the tryptophan residues were barried into the molecule was recognized, and, between pH 2 and 0.64, the change was attained to maximum. The secondary structure, β-structure, of the 11S component was almost stable at pH 1.22.