scholarly journals CD investigations on conformation of H-X-(Pro)n-Y-OH peptides (X = Trp, Tyr; Y = Tyr, Met); models for intramolecular long range electron transfer.

1995 ◽  
Vol 42 (2) ◽  
pp. 259-268 ◽  
Author(s):  
K L Wierzchowski ◽  
K Majcher ◽  
J Poznański
Keyword(s):  
Electron Transfer ◽  
Long Range ◽  
Peptide Bond ◽  
Cd Spectroscopy ◽  
Helical Conformation ◽  
Large Temperature ◽  
Cd Spectra ◽  
Negative Band ◽  
Left Handed ◽  
In Trans

Conformations of three series of peptides: H-Trp-(Pro)n-Tyr-OH (n = 1-5), H-Trp-(Pro)n-Met-OH (n = 1-3) and H-Tyr-(Pro)n-Met-OH (n = 1-3), used as models in studies on long range electron transfer through protein matrix, were investigated by CD spectroscopy in aqueous solution at pH 5.2 in the temperature range of 10 degrees C-90 degrees C. CD spectra of their component N- and C-terminal dipeptide and oligoproline fragments were also measured under similar conditions. In interpretation of the spectra the cistrans equilibrium about X-Pro bonds was taken into account and CD spectra of Trp-Pro and Tyr-Pro chromophores in trans and cis configuration of the peptide bond were evaluated. The spectra of n = 3-5 peptides from the first series and those with n = 2-3 from the other two series exhibit a strong negative band in the 202-207 nm region, the strength of which is proportional to the number of Pro residues in the (Pro)n bridge, and characterized by a large temperature decrement. In view of close similarity between characteristics of this band and the 206 nm band of aqueous oligoproline peptides (n > or = 3), known to attain a left handed helical conformation similar to that of 3(1) helix of the all-trans poly-L-proline II, this band was attributed to a conformation of the latter type. H-Trp-(Pro)2-Tyr-OH does not form this conformation due to sterical interaction between the two bulky aromatic side chains. Conclusions drawn from analysis of the CD spectra are supported by 1H and 13CNMR data reported elsewhere.

Interaction of Organophosphorus Insecticide Methylparathion with Calf Thymus DNA and a Synthetic DNA Duplex

1995 ◽  
Vol 50 (11-12) ◽  
pp. 820-823 ◽  
Author(s):  
Janusz Blasiak ◽  
Vladimír Kleinwächter ◽  
Zofia Walter ◽  
Renata Žaludová
Keyword(s):  
Cd Spectroscopy ◽  
Organophosphorus Insecticide ◽  
Calf Thymus Dna ◽  
Molar Ratio ◽  
Cd Spectra ◽  
Transition Range ◽  
Synthetic Dna ◽  
Negative Band ◽  
Calf Thymus ◽  
Ct Dna

Abstract The interaction of an organophosphorus insecticide methylparathion (O.O-dimethyl 0-4-nitrophenyl phosphorothioate) with double-stranded DNA was characterized by UV and circular dichroism (CD) spectroscopy. Two kinds of DNA were employed: calf thymus DNA (CT DNA) and a synthetic two-stranded oligomer of sequence 5′-d(TTGGATCCGAATT-CAAGCTT)-3′ Melting curves and CD spectra were taken for the DNAs in the presence of the insecticide at methylparathion/DNA base pair molar ratio of 0.5. The insecticide evoked a decrease of the melting temperature and a broadening of the transition range for CT DNA. Similar effects were observed for the synthetic oligomer but they were less pronounced than in the case of CT DNA. Methylparathion evoked a slight shift and an increase in the amplitude of the negative band in the CD spectra of both DNAs. Obtained results indicate that methylparathion may perturb the thermal stability and conformation of DNA, which is an evidence that the insecticide has an ability to interact directly with DNA.

Sequential oligopeptides containing lysene: Synthesis, circular dichroism, conformation and complexes with DNA

1988 ◽  
Vol 53 (2) ◽  
pp. 389-410 ◽  
Author(s):  
Hana Votavová ◽  
Jana Pírková ◽  
Vladimír Gut ◽  
Karel Bláha
Keyword(s):  
Conformational Changes ◽  
Double Helix ◽  
Cd Spectroscopy ◽  
Helical Conformation ◽  
Cd Spectra ◽  
Polymeric Carrier ◽  
Aqueous Methanol ◽  
Helix Formation ◽  
Fragment Condensation ◽  
Α Helix

Oligomeric (Lys-Ala-Ala)1-5 and (Lys-Leu-Ala)1-4 were synthesized by fragment condensation in solution, (Lys-Ala-Ala)10Ape was obtained by stepwise synthesis from the tripeptide monomer on a polymeric carrier. Conformation of the compounds in water, aqueous methanol and trifluoroethanol was studied by CD spectroscopy. The dimer and trimer in both the structural series show no signs of α-helix formation. The higher oligopeptides exist in random conformation in aqueous solutions, whereas in the presence of alcohols they are partly in the α-helical conformation, depending on the chain length and the character and concentration of the alcohol. However, the ability of α-helix formation is substantially lower even for the studied decamer than for polytripeptides of DP ~30 and higher. According to the CD spectra, the conformational changes resulting from interaction of the oligopeptides with DNA are generally small for both components. The changes of DNA structure may be interpreted as winding of the double helix. The oligopeptide conformation is very little affected by the complexation and is invariably random, contrary to that of the corresponding polypeptides which in complexes with DNA are at least partially α-helical.

Intramolecular long-range electron transfer in the .alpha.-hemoglobin subunit

1988 ◽  
Vol 110 (17) ◽  
pp. 5753-5756 ◽  
Author(s):  
M. Faraggi ◽  
Michael H. Klapper
Keyword(s):  
Electron Transfer ◽  
Long Range

Oxidative DNA damage through long-range electron transfer

Nature ◽  
1996 ◽  
Vol 382 (6593) ◽  
pp. 731-735 ◽  
Author(s):  
Daniel B. Hall ◽  
R. Erik Holmlin ◽  
Jacqueline K. Barton
Keyword(s):  
Dna Damage ◽  
Electron Transfer ◽  
Long Range ◽  
Oxidative Dna Damage
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