An N-methylated residue at the n -3 position of the chain was used to reduce the maximum number of H-bonds realizable by some D,L-alternating oligopeptides ing4 '-, TtB5 '-and Tl/rs 6-helices and thus increase for the oligopeptides, the relative stability of largerb -helices. With D,L-alternating oligoleucines of the series Boc-Leu,-OMe, however, this approach did not produce the helices expected. Although tl/r"-helices with only one free NH per strand would theoretically be possible, the N-methylated oligoleucines formed instead flawed g4 4-helices having three free NH's in CHCI, as well as in other solvents of low polarity. These observations confirm that the stability ofg-helices does not depend only on the number of intra-or interstrand H-bonds, and corroborate the idea thatg -helices with large cavities are inherently unstable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.