Hintergrund: Lungenzellen sind während Atmung und Beatmung zyklischer Dehnung ausgesetzt. Es wurde bereits gezeigt, dass Dehnung mit hoher Amplitude zu Apoptose von alveolären Typ II (ATII) – Zellen in vitro führen kann. Der PI3K/Akt-Signalweg stellt einen wichtigen Mechanismus dar, Zellüberleben zu vermitteln. In dieser Studie wurde der Einfluss von zyklischer Dehnung auf den PI3K/Akt-Signalweg untersucht.

A newly designed host–guest approach is introduced as a experimental tool to explore the relationship between the sequence of peptides and their secondary structure. From the CD spectra of the host–guest peptides studied, a tentative scale for the α‐helix potential in 2,2,2‐trifluorethanol of guest amino acids is delineated. The conformational preferences are also examined in β‐structure supporting media (solid state, CH 2 Cl 2 , CH 3 OH, H 2 O) using ir‐absorption and CD techniques. Scales for the β‐forming tendency of guest amino acid residues in the different media are delineated. It is shown that the preferred conformation of the host–guest peptides is a function of the medium, the chain length, and the protecting groups. Given the fact that conformational effects are important in peptide synthesis, the tentative scales may serve as a guideline to predict secondary structures of side‐chain‐protected or ‐deprotected peptides in a given solvent, complementing the well‐known empirical conformational prediction parameters.

Chemischer InformationsdienstVolume 16, Issue 34 Reviews ChemInform Abstract: CONFORMATIONAL STUDIES ON MODEL PEPTIDES. THEIR CONTRIBUTION TO SYNTHETIC, STRUCTURAL AND FUNCTIONAL INNOVATIONS ON PROTEINS F. MASER, F. MASERSearch for more papers by this authorK. BODE, K. BODESearch for more papers by this authorV. N. R. PILLAI, V. N. R. PILLAISearch for more papers by this authorM. MUTTER, M. MUTTERSearch for more papers by this author F. MASER, F. MASERSearch for more papers by this authorK. BODE, K. BODESearch for more papers by this authorV. N. R. PILLAI, V. N. R. PILLAISearch for more papers by this authorM. MUTTER, M. MUTTERSearch for more papers by this author First published: August 27, 1985 https://doi.org/10.1002/chin.198534384AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue34August 27, 1985 RelatedInformation

The disruption of the sparingly soluble, self-associated species (β-structure) of the polymer-bound, N-protected peptides Boc-L-Ala-Gly-L-lle-(L-Ala)2-NHPEG and Boc-(L-Ala)2-Gly-L-lle-(L-Ala)2-NHPEG [PEG = poly(ethylene glycol)] in methylene chloride by increasing amounts of N,N-dimethylformamide or dimethyl sulphoxide has been monitored by following the disappearance of the intense amide I or A i.r. bands of the strongly intermolecularly hydrogen-bonded molecules; this suggests the use of this method for the quantitative titration of the extent of self-association in PEG-bound peptides.

Using the host‐guest technique, tentative scales for the helix‐inducing power and the β‐structure‐forming potential of various side‐chain protected amino acid residues in trifluoro‐ethanol are established mainly by CD measurements. The generally lower tendency for β‐structure formation of the host–guest peptides compared to that of the host peptide is discussed. The influence of these conformational features on the solubility of the peptides is also pointed out.

Primary and tertiary amine‐initiated polymerizations of L ‐alanine‐ N ‐carboxyanhydride ( L ‐Ala‐NCA) were conducted at 20 or 100°C in a variety of solvents. The 75.5‐MHz 13 C‐nmr CP/MAS spectra of the resulting poly( L ‐alanines) revealed that all samples contain both α‐helix and pleated‐sheet structures. Depending on the reaction conditions the α‐helix content varied between ca. 1 and 99%. Reprecipitation from aprotic nonsolvents does not change the α‐helix/β‐sheet ratio, indicating that this ratio is thermodynamically controlled. Since relatively large amounts of oligopeptides of degree of polymerization ( DP ) 4–6 can be extracted by means of acetic acid, it is concluded that (a) most poly( L ‐alanines) possess a bimodal molecular weight distribution, (b) the oligopeptide fraction with DP ⩽ 11 is responsible for the β‐sheet fraction of all samples, and (c) the two‐stage crystal growth proposed by Komoto and Kawai is not correct. Solubilizing initiators such as poly(ethylene oxide) NH 2 prevent the precipitation of oligoalanine and, thus, the formation of a β‐sheet structure. 13 C‐nmr CP/MAS measurements also show that tri‐ and tetra‐ L ‐alanines form insoluble β‐sheet structures.