title: N-(tert-butoxycarbonyl)-O-allyl-L-seryl-α-aminoisobutyryl-L-valine methyl ester: a protected tripeptide with an allylated serine residue.
abstract: The title compound [systematic name (6S,12S)-methyl 6-(allyloxymethyl)-12-isopropyl-2,2,9,9-tetramethyl-4,7,10-trioxo-3-oxa-5,8,11-triazatridecan-13-oate], C(21)H(37)N(3)O(7), containing the little studied O-allyl-L-serine residue [Ser(All)], crystallizes in the monoclinic space group C2 with one molecule in the asymmetric unit. The compound is an analogue of the Ser140-Val142 segment of the water channel aquaporin-4 (AQP4). It forms a distorted type-II β-turn with a P(II)-3(10L)-P(II) backbone conformation (P(II) is polyproline II). The overall backbone conformation is markedly different from that of the CO(Pro139)-Val142 stretch of rat AQP4, but is quite similar to the corresponding segment of human AQP4, despite significant differences at the level of the individual residues. The side chain of the Ser(All) residue adopts a gauche conformation relative to the backbone CO-C(α) and C(α)-N bonds. The H atoms of the two CH(2) groups in the Ser(All) side chain are almost eclipsed. The crystal packing of the title compound is divided into one-molecule-thick layers, each layer having a hydrophilic core and distinct hydrophobic interfaces on either side.
authors: Department of Chemistry, University of Oslo, PO Box 1033 Blindern, N-0315 Oslo, Norway.
authors: Hadgu Girmay
authors: HG
authors: Gebreslasie
authors: Øyvind
authors: Ø
authors: Jacobsen
authors: Carl Henrik
authors: CH
authors: Görbitz
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D004952:Esters; D006801:Humans; D008968:Molecular Conformation; D015394:Molecular Structure; D009842:Oligopeptides / Q000737:chemistry*; D051381:Rats; D012694:Serine / Q000737:chemistry*; D014633:Valine / Q000737:chemistry*
chemical_list: D004952:Esters; C562179:N-(tert-butoxycarbonyl)-O-allyl-L-seryl-alpha-aminoisobutyryl-L-valine methyl ester; D009842:Oligopeptides; D012694:Serine; D014633:Valine