Two pentadehydropeptides with different configurations of the ΔPhe residues

Abstract

Comparison of the crystal structures of two pentadehydropeptides containing ÁPhe residues, namely (Z,Z)-N-(tertbutoxycarbonyl)glycyl-, -phenylalanylglycyl-, -phenylalanylglycine (or Boc 0 -Gly 1 -Á Z Phe 2 -Gly 3 -Á Z Phe 4 -Gly 5 -OH) methanol solvate, C 29 H 33 N 5 O 8 ÁCH 4 O, (I), and (E,E)-N-(tertbutoxycarbonyl)glycyl-, -phenylalanylglycyl-, -phenylalanylglycine (or Boc 0 -Gly 1 -Á E Phe 2 -Gly 3 -Á E Phe 4 -Gly 5 -OH), C 29 H 33 N 5 O 8 , (II), indicates that the Á Z Phe residue is a more effective inducer of folded structures than the Á E Phe residue. The values of the torsion angles ' and show the presence of two type-III 0 -turns at the Á Z Phe residues and one type-II -turn at the Á E Phe residue. All amino acids are linked trans to each other in both peptides. -Turns present in the peptides are stabilized by intramolecular 4!1 hydrogen bonds. Molecules in both structures form two-dimensional hydrogen-bond networks parallel to the (100) plane.

Two phosphonodehydrotripeptides: Boc0–Gly1–Δ(Z)Phe2–α-Abu3PO3Me2and Boc0–Gly1–Δ(Z)Phe2–α-Nva3PO3Et2

“…Important bond lengths, bond angles and torsion angles are presented in Table 1. The C C (C8 C9) distance in the ÁPhe residue of (I) is 1.329 (5) Å , which agrees with other structures containing ÁPhe (Głó wka et al, 1987;Makowski et al, 2005Makowski et al, , 2010 and also with the classical value for a C C bond (Allen et al, 1987). Because of the unsaturated character of the bond between C and C , the side-chain atoms of the ÁPhe residue are closer to the main chain than in the saturated form.…”

“…In previous reports we have described the crystal structures of dehydropeptides containing two ,-dehydroamino acid residues (with a double bond between the C and C atoms) (Makowski et al, 2005(Makowski et al, , 2006(Makowski et al, , 2010Lisowski et al, 2007). In short peptides, the presence of one or more ÁPhe residues causes a -turn conformation (Głó wka et al, 1987;Głó wka, 1988) and a 3 10 helical conformation in longer peptides (Rajashankar et al, 1992;Padmanabhan & Singh, 1993;Rajashankar, Ramakumar, Mal et al, 1995).…”

Effect of the ΔPhe residue configuration on a didehydropeptides conformation: A combined CD and NMR study

“…It has been found that in the solid state a ∆Phe residue of the Z configuration induces β-turns in short sequences [2][3][4][5][6] and a 3 10 -helix in longer ones or peptides with more than one dehydro residue. 4,[7][8][9][10][11][12][13][14][15][16][17][18][19] Similar conformational properties of ∆ Z Phe have been observed in solution by NMR 8,11,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and CD, 18,19,[27][28][29][30][31][32][33][34][35][36]…”

Handedness preference and switching of peptide helices. Part II: Helices based on noncodedα‐amino acids

“…As in the case of the aforementioned Aib peptides discussed, many ΔPhe‐containing linear peptides are highly crystalline materials. This property allows X‐ray diffraction analyses to be performed . Almost all of them are characterized by the Δ Z Phe configurational isomer.…”

“…The 1 ← 4 intramolecular H‐bonds are shown as dashed lines (adapted from Ref. , with permission from the International Union of Crystallography).…”