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.

Synthesis, resolution, and absolute configuration of 1-phenyl-1-methyl-1-silacyclohexanone-2

1970 ◽  
Vol 48 (5) ◽  
pp. 818-823 ◽  
Author(s):  
A. G. Brook ◽  
H. W. Kucera ◽  
D. M. MacRae
Keyword(s):  
Absolute Configuration ◽  
Active Form ◽  
Dispersion Curves ◽  
Convincing Evidence ◽  
Optically Active ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Asymmetric Center ◽  
Optical Rotatory ◽  
Subsequent Oxidation

The synthesis and resolution of 1-phenyl-1-methyl-1-silacyclohexanone-2 by oxidative hydroboration of the related silacyclohexene to the silacyclohexanol, resolution of this via the strychnine salt of the phthalate half-ester, and subsequent oxidation of the silacyclohexanol to the silacyclohexanone is described. The carbon analog 1-phenyl-1-methylcyclohexanone-2 was also synthesized in optically active form. The (+)-enantiomers of the two ketones had similar optical rotatory dispersion curves, presenting convincing evidence for the identity of their configurations, and the carbon compound could be degraded without affecting the asymmetric center to (−)-(R)-2-phenyl-2-methylhexandioic acid, thereby establishing the absolute configurations of both compounds.

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 Application of Optical Rotatory Dispersion Techniques to the Determination of Coordination of Optically Active Ligands

1964 ◽  
Vol 3 (9) ◽  
pp. 1256-1258 ◽  
Author(s):  
Dinesh C. Bhatnagar ◽  
Stanley Kirschner
Keyword(s):  
Optically Active ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory

THE EFFECTS OF OPTICALLY INACTIVE IONS ON THE ROTATORY DISPERSION OF ASYMMETRIC COMPLEX IONS

1961 ◽  
Vol 39 (11) ◽  
pp. 2360-2370 ◽  
Author(s):  
Marvin J. Albinak ◽  
Dinesh C. Bhatnagar ◽  
Stanley Kirschner ◽  
Anthony J. Sonnessa
Keyword(s):  
Water Solution ◽  
Inorganic Compounds ◽  
Optically Active ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Optical Rotatory ◽  
Complex Ions ◽  
Ionic Charge ◽  
Sodium Potassium ◽  
Active Anion

Considerable interest in the optical rotatory dispersion of asymmetric organic and inorganic compounds and its application to the elucidation of their structures has arisen in recent years. In order to study the effects of optically inactive ions on the rotatory dispersion of asymmetric complex ions, a series of salts was prepared of two active cations: levo cis-oxalato-bis(ethylenediamine)cobalt(III) and levo tris(ethylenediamine)chromium(III). Salts prepared included the fluoride, chloride, bromide, iodide, tetrafluoroborate, perchlorate, sulphate, and phosphate. In order to study this effect on an optically active anion, the lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, and barium salts of dextro and levo tris(oxalato)rhodate(III) were also prepared. Rotatory dispersion curves and absorption spectra were obtained for all salts in water solution. A comparison of the curves within a series showed definite trends in changes of wavelength and intensity of maxima of rotation and absorption with changes in both the ionic charge/size ratio (ionic potential) and polarizability of the optically inactive ions.

scholarly journals Ligand-apomyoglobin interactions. Configurational adaptability of the haem-binding site

1976 ◽  
Vol 155 (3) ◽  
pp. 669-678 ◽  
Author(s):  
K E Lind ◽  
J V Møller
Keyword(s):  
Serum Albumin ◽  
Protoporphyrin Ix ◽  
Association Constants ◽  
The Other ◽  
Optical Rotatory Dispersion ◽  
Rotatory Dispersion ◽  
Bromophenol Blue ◽  
Optical Rotatory ◽  
Binding Studies ◽  
High Affinity

1. The interaction of the haem-binding region of apomyoglobin with different ligands was examined by ultrafiltration, equilibrium dialysis and spectrophotometry, to study unspecific features of protein-ligand interactions such as they occur in, for example, serum albumin binding. 2. Apomyoglobin, in contrast with metmyoglobin, binds at pH 7, with a high affinity, one molecule of Bromophenol Blue, bilirubin and protoporphyrin IX, two molecules of n-dodecanoate and n-decyl sulphate and four molecules of n-dodecyl sulphate and n-tetradecyl sulphate. 3. The number of high-affinity sites and/or association constants for the alkyl sulphates are enhanced by an increase of hydrocarbon length, indicating hydrophobic interactions with the protein. 4. Measurements of the temperature-dependence of the association constants of the high-affinity sites imply that the binding processes are largely entropy-driven. 5. Binding studies in the presence of two ligands show that bilirubin plus Bromophenol Blue and dodecanoate plus Bromophenol Blue can be simultaneously bound by apomyoglobin, but with decreased affinities. By contrast, the apomyoglobin-protoporphyrin IX complex does not react with Bromophenol Blue. 6. Optical-rotatory-dispersion measurements show that the laevorotation of apomyoglobin is increased towards that of metmyglobin in the presence of haemin and protoporphyrin IX. Small changes in the optical-rotatory-dispersion spectrum of apomyoglobin are observed in the presence of the other ligands. 7. It is concluded that the binding sites on apomyoglobin probably do not pre-exist but appear to be moulded from predominantly non-polar amino acid residues by reaction with hydrophobic ligands. 8. Comparison with data in the literature indicates that apomyoglobin on a weight basis has a larger hydrophobic area avaialble for binding of ligands than has human serum albumin. On the other hand, the association constants of serum for the ligands used in this study are generally somewhat larger than those of apomyoglobin.

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