N' capping interactions. (A) N' Thr and (B) Asn contribute sidechain-backbone hydrogen bonds. Carbons in αL turn are orange, others are in green. Sidechain atoms are only shown for the capping residues. Thr caps shown: 1ZY7_A 339-343, 1OVM_A 292-296 and 1GSA 188-192. Asn caps shown: 1AA7_A 85-89, 1P4C_A 254-258 and 1KQF_A 521-525. (C) The D-Asp capping interaction for an αR helix from a designed peptide (CSD ID - GORVIP) . D-Asp carbons are colored orange.