English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

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 cis<-->trans 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.

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.