Electrospray Ionization Tandem Mass Spectrometric Study of Protonated and Alkali-Cationized α/ε-Hybrid Peptides: Differentiation of a Pair of Dipeptide Positional Isomers
is totally absent for its positional isomer Boc-NH-ε-Caa-L-Ala-OCH3 (6), which instead shows significant loss of t-butanol. The formation of the [M + Cat – C4H8]+ ion is totally absent and [M + Cat – Boc + H]+ is prominent in the CID of the [M + Cat]+ ion of Boc-NH-L-Ala-ε-Caa-OCH3 (1), whereas the former is highly abundant and the latter is of low abundance for its positional isomer Boc-NH-ε-Caa-L-Ala-OCH3
Theoretical and Experimental Studies on α/ε-Hybrid Peptides: Design of a 14/12-Helix from Peptides with Alternating (<i>S</i>)-C-Linked Carbo-ε-amino Acid [(<i>S</i>)-ε-Caa<sub>(x)</sub>] and <scp>l</scp>-Ala
作者:Gangavaram V. M. Sharma、Bommagani Shoban Babu、Deepak Chatterjee、Kallaganti V. S. Ramakrishna、Ajit C. Kunwar、Peter Schramm、Hans-Jörg Hofmann
DOI:10.1021/jo901277a
日期:2009.9.4
give novelα/ε-hybrid peptides in 1:1 alternation. Conformational analysis on penta- and hexapeptides by NMR (in CDCl3), CD, and MD studies led to the identification of robust 14/12-mixed helices. This is in agreement with the data from a theoretical conformational analysis on the basis of ab initio MO theory providing a complete overview on all formally possible hydrogen-bonded helixpatterns of α/ε-hybrid