Helix, length stability

There are a number of small peptide-forming channels. One of the most studied is gramicidin. Gramicidin is a mixture of similar pentadecapeptides containing alternating D- and L-amino acids. These peptides can form a helix with an internal diameter of around 4 A. The helix length is approximately half of the membrane width and, upon being dimerization stabilized by tail to tail interactions, they form... 

Synthetic peptides have been extensively used to study the thermal stability and folding of the triple helix. These peptides can be synthesized as either single chains or cross-linked peptides. Early on, such peptides were synthesized by polycondensation of tri- or hexapeptides, which led to a broad mass distribution that was difficult to separate. With the advances of solid-phase synthesis methods, peptides with defined chain length became available. The most studied collagen-like peptides are (Gly-Pro-Pro) or (Pro-Pro-Gly) and (Gly-Pro-4(if)Hyp) or (Pro-4(if)Hyp-Gly) with n varying from 5 to 15. Sutoh and Noda" " introduced the concept... 

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