scholarly journals The nature of the circular-dichoric spectra of complexes between ribonuclease A and nucleotides

1977 ◽  
Vol 167 (3) ◽  
pp. 749-757 ◽  
Author(s):  
S M Dudkin ◽  
L V Karabashyan ◽  
M Y Karpeisky ◽  
S N Mikhailov ◽  
N S Padyukova ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Ribonuclease A ◽  
Circular Dichroic Spectrum ◽  
Nucleotide Conformation ◽  
Anti Conformation ◽  
Two Factors ◽  
Wavelength Absorption ◽  
Comparison Of The Results ◽  
Circular Dichroïsm ◽  
Circular Dichroic

The circular-dichroism and proton-magnetic-resonance spectra of complexes of ribonuclease A with dihydrouridine 3′-phosphate, 2′- and 3′-CMP, arabinosyl-3′-CMP, 1-(2-hydroxyethyl)cytosine 2′-phosphate and 1-(3-hydroxypropyl)cytosine 3′-phosphate were studied. Comparison of the results shows that non-additivity of the circular-dichroic spectrum of an enzyme-nucleotide complex may be due to: (a), alteration of the circular dichroic spectrum of the nucleotide under the influence of the asymmetric protein matrix (induced dichroism), and (b) a change in the nucleotide conformation. The contribution of each of the two factors was estimated to calculate the circular-dichoroic spectra of 2′-CMP and 3′-CMP in complex with ribonuclease A. 3′-CMP in this complex was characterized by negative circular dichroism in the long-wavelength absorption band of the nucleotide, whereas 2′-CMP was characterized by positive circular dichroism. Since both nucleotides in the complex are known to be in an anti conformation, it follows that even small changes in the conformation considerably modify the circular-dichroic spectrum of the nucleotide in complex with the enzyme.

Linear oligopeptides. XXVII. Contribution to the circular dichroism of internal peptide chromophores

1976 ◽  
Vol 54 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Claudio Toniolo ◽  
Gian Maria Bonora
Keyword(s):  
Circular Dichroism ◽  
Solvent Polarity ◽  
Guanidinium Chloride ◽  
Negative Band ◽  
Circular Dichroic Spectrum ◽  
Internal Peptide ◽  
Circular Dichroïsm ◽  
Sulfur Containing ◽  
Circular Dichroic ◽  
Molar Ellipticity

The contribution to the circular dichroism of L-Ala-L-Ala, L-Nva-L-Nva, L-Val-L-Val, L-Leu-L-Leu, L-Ile-L-Ile, L-Cys(Me)-L-Cys(Me), L-Met-L-Met, and L-Phe-L-Phe internal peptide chromophores in 1,1,1,3,3,3-hexafluoropropan-2-ol were calculated by subtracting the total molar ellipticity values of N- and C-protected homo-trimers from those of the pertinent protected homo-tetramers.The circular dichroism of the internal peptide chromophore of aliphatic hydrocarbon- and sulfur-containing peptides, each of the L-configuration, show a negative band at 2l5–230 nm accompanied by a more intense negative band near 200 nm. A structured weak and negative band near 260 nm along with bands at 240 nm (negative), 222 nm (positive), and 210.5 nm (negative) of progressively increasing intensity are apparent in the circular dichroic spectrum of L-Phe-L-Phe internal peptide chromophore. The effect of solvent polarity is discussed in the case of L-Val-L-Val and L-Ala-L-Ala internal peptide chromophores.Among the protected homo-trimers and tetramers only those of L-alanine are soluble in aqueous solution; consequently, the effect of water as a function of temperature, urea, and guanidinium chloride on the L-Ala-L-Ala internal peptide chromophore circular dichroism was established.

Organic photodiodes from homochiral l-proline derived squaraine compounds with strong circular dichroism

2017 ◽  
Vol 19 (10) ◽  
pp. 6996-7008 ◽  
Author(s):  
Matthias Schulz ◽  
Majvor Mack ◽  
Oliver Kolloge ◽  
Arne Lützen ◽  
Manuela Schiek
Keyword(s):  
Circular Dichroism ◽  
Polarized Light ◽  
Active Layers ◽  
Circular Dichroïsm ◽  
Circular Dichroic ◽  
Circular Polarized Light

We demonstrate the feasibility of inserting highly circular dichroic active layers into an organic photodiode as a potential detector for circular polarized light.

scholarly journals Bis-Lactam Peptide [i, i+4]-Stapling with α-Methylated Thialysines

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4506
Author(s):  
Bo Wu ◽  
Weiping Zheng
Keyword(s):  
Circular Dichroism ◽  
Ribonuclease A ◽  
Rnase A ◽  
Peptide Sequence ◽  
Stability Assessment ◽  
Model Peptide ◽  
Stapled Peptides ◽  
Stapled Peptide ◽  
Proteolytic Stability ◽  
Circular Dichroïsm

Four bis-lactam [i, i+4]-stapled peptides with d- or l-α-methyl-thialysines were constructed on a model peptide sequence derived from p110α[E545K] and subjected to circular dichroism (CD) and proteolytic stability assessment, alongside the corresponding bis-lactam [i, i+4]-stapled peptide with l-thialysine. The % α-helicity values of these four stapled peptides were found to be largely comparable to each other yet greater than that of the stapled peptide with l-thialysine. An l-α-methyl-thialysine-stapled peptide built on a model peptide sequence derived from ribonuclease A (RNase A) was also found to exhibit a greater % α-helicity than its l-thialysine-stapled counterpart. Moreover, a greater proteolytic stability was demonstrated for the l-α-methyl-thialysine-stapled p110α[E545K] and RNase A peptides than that of their respective l-thialysine-stapled counterparts.

Circular dichroism of helical polynucleotide chains

1967 ◽  
Vol 297 (1448) ◽  
pp. 150-162 ◽  
Keyword(s):  
Circular Dichroism ◽  
Nucleic Acids ◽  
Helical Structure ◽  
Optical Rotatory Dispersion ◽  
Random Coil ◽  
Helical Conformation ◽  
Polyadenylic Acid ◽  
V Region ◽  
Circular Dichroïsm ◽  
Circular Dichroic

In contrast to relatively well developed experimental and theoretical studies on polypeptides and proteins (see Gratzer 1967 and McLachlan 1967, this volume) the investigation of optical activity of polynucleotides and nucleic acids were very restricted. The optical rotatory dispersion curves of polynucleotides examined in the visible and near u. v. fit one-term Drude equation regardless of the conformation (Fresco 1961; Levedahl & James 1957; Ts’o, Helmkamp & Sander 1962). Recent circular dichroism (c. d.) measurements of several polynucleotides and nucleic acids (figure 1) indicated clearly the presence of dichroic bands in the u. v. region of base absorption which can be related to the dissymmetrical helical conformation (Brahms 1963). The intensity of circular dichroic bands decreases strongly under the conditions in which the helical structure is unstable and goes to random coil form (Brahms 1964; Brahms & Mommaerts 1964). Thus polyadenylic acid (poly A ) is known according to X-ray data to exist at acid pH in a helical two strand and right handed conformation (Rich, Davies, Crick & Watson 1961). In acid solution the same polyadenylic acid exhibits strong circular dichroic bands which disappear at high temperature (figure 2).

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