organic compounds
H–D-Phe–D-Pro–Gly methyl ester hydrochloride monohydrate
aOsaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
*Correspondence e-mail: doit@gly.oups.ac.jp
The conformation of the title tripeptide methyl ester hydrochloride monohydrate, 1-[2-(methoxycarbonylmethylaminocarbonyl)pyrrolidin-1-ylcarbonyl]-2-phenylethanaminium chloride monohydrate, C17H24N3O4+·Cl−·H2O, is extended, but the structure cannot be classified as any typical secondary structure. Interactions through water molecules and chloride ions were formed, in addition to peptide–peptide hydrogen bonds, stabilizing the molecular packing. In comparison with the previous β-turn structure of the Phe–D-Pro–Gly analogue [Doi, Ichimiya & Asano (2007). Acta Cryst. E63, o4691], it was suggested that the difference between the chiralities of Phe and Pro residues of the title compound is important to induce the β-turn structure.
Related literature
For related literature, see: Cremer & Pople (1975); Doi, Fujita et al. (2001); Doi, Ichimiya et al. (2007); Espinosa & Gellman (2000); Llamas-Saiz et al. (2007); Tamaki et al. (1985); Yamada et al. (2002).
Experimental
Crystal data
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Data collection: SMART (Bruker, 1998); cell SAINT-Plus (Bruker, 1998);; data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S160053680800528X/pv2069sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S160053680800528X/pv2069Isup2.hkl
The title compound was synthesized by a conventional liquid-phase method and the protected peptide, Boc–D-Phe–D-Pro–Gly–OMe (Boc = t-Butyloxycarboxy; OMe = methylester), was obtained. Boc group was removed by using HCl/dioxane, and the hydrocloride salt was obtained. Crystals were grown from aqueous acetonitrile solutions by vapor diffusion method.
The non-H atoms were refined anisotropically. H atoms were treated as riding atoms with distances C—H = 0.95–1.00 Å, N—H (–NH3+) = 0.91 Å and N—H (CONH) = 0.88 Å; Uiso(H) = 1.2Uiso(C), Uiso(H) = 1.5Ueq(Cmethyl), Uiso(H) = 1.2Ueq(NCONH) and Uiso(H) = 1.5Ueq(NNH3). H atoms of the water molecule were found in a difference Fourier map considering hydrogen-bond networks and fixed during refinements with Uiso(H) = 1.2Ueq(O). The
was based on the starting materials and was established by Flack parameter.Data collection: SMART (Bruker, 1998); cell
SMART (Bruker, 1998); data reduction: SAINT-Plus (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).C17H24N3O4+·Cl−·H2O | F(000) = 824 |
Mr = 387.86 | Dx = 1.334 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 8392 reflections |
a = 7.3707 (5) Å | θ = 2.3–28.3° |
b = 9.6667 (7) Å | µ = 0.23 mm−1 |
c = 27.099 (2) Å | T = 90 K |
V = 1930.8 (2) Å3 | Cubic, colourless |
Z = 4 | 0.40 × 0.35 × 0.35 mm |
Bruker SMART APEX CCD area-detector diffractometer | 4553 independent reflections |
Radiation source: MacScience, M18XCE rotating anode | 4540 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.020 |
Detector resolution: 8.366 pixels mm-1 | θmax = 27.9°, θmin = 2.6° |
ω–scan | h = −9→9 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | k = −12→12 |
Tmin = 0.874, Tmax = 0.923 | l = −35→35 |
23047 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.032 | H-atom parameters constrained |
wR(F2) = 0.088 | w = 1/[σ2(Fo2) + (0.0703P)2 + 0.8632P] where P = (Fo2 + 2Fc2)/3 |
S = 0.85 | (Δ/σ)max = 0.001 |
4553 reflections | Δρmax = 0.46 e Å−3 |
237 parameters | Δρmin = −0.21 e Å−3 |
0 restraints | Absolute structure: Flack (1983), 1920 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.03 (4) |
C17H24N3O4+·Cl−·H2O | V = 1930.8 (2) Å3 |
Mr = 387.86 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.3707 (5) Å | µ = 0.23 mm−1 |
b = 9.6667 (7) Å | T = 90 K |
c = 27.099 (2) Å | 0.40 × 0.35 × 0.35 mm |
Bruker SMART APEX CCD area-detector diffractometer | 4553 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 4540 reflections with I > 2σ(I) |
Tmin = 0.874, Tmax = 0.923 | Rint = 0.020 |
23047 measured reflections |
R[F2 > 2σ(F2)] = 0.032 | H-atom parameters constrained |
wR(F2) = 0.088 | Δρmax = 0.46 e Å−3 |
S = 0.85 | Δρmin = −0.21 e Å−3 |
4553 reflections | Absolute structure: Flack (1983), 1920 Friedel pairs |
237 parameters | Absolute structure parameter: 0.03 (4) |
0 restraints |
Geometry. Cremer & Pople Puckering Parameters [D. Cremer & J.A. Pople, J.Amer.Chem.Soc., 97, (1975), 1354–1358] ——————————————————————- Q(2) = 0.3608 (15) A ng., Phi(2) = 293.1 (2) Deg The equation of the plane is of the form: P * x + Q * y + R * z - S = 0 where P, Q, R, S are constants and x, y, z are fractional coordinates. P = 5.153 (2), Q = 1.935 (5), R = -18.602 (8), S = -9.378 (8) Atom Distance x y z X Y Z * O(18): -0.0397 (9) 0.4138 0.9441 0.7191 3.0500 9.1267 19.4869 * N(20): 0.0350 (11) 0.2674 0.8185 0.6615 1.9711 7.9123 17.9252 * C(10): 0.0337 (12) 0.4982 0.7074 0.7139 3.6722 6.8378 19.3462 * C(18): -0.0103 (12) 0.3858 0.8324 0.6981 2.8434 8.0464 18.9186 * C(20): 0.0268 (13) 0.1632 0.9399 0.6457 1.2030 9.0862 17.4973 * C(23): -0.0454 (14) 0.2080 0.6914 0.6361 1.5330 6.6837 17.2377 P = 4.443 (3), Q = 0.711 (4), R = 21.531 (8), S = 15.452 (5) Atom Distance x y z X Y Z * O(24): 0.1064 (11) 0.4222 1.0289 0.6015 3.1119 9.9466 16.2998 * N(30): 0.0315 (11) 0.2213 1.1812 0.6344 1.6313 11.4182 17.1924 * C(20): -0.1560 (13) 0.1632 0.9399 0.6457 1.2030 9.0862 17.4973 * C(24): 0.0232 (13) 0.2849 1.0527 0.6252 2.1002 10.1765 16.9412 * C(30): -0.1661 (14) 0.2878 1.2994 0.6076 2.1213 12.5607 16.4662 * H(30): 0.16108 0.1378 1.1928 0.6573 1.0157 11.5304 17.8122 |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
Cl | 0.11272 (5) | 0.69212 (3) | 0.784634 (14) | 0.02274 (9) | |
N10 | 0.52851 (16) | 0.72346 (11) | 0.76814 (4) | 0.0135 (2) | |
H10A | 0.6034 | 0.7967 | 0.7737 | 0.020* | |
H10B | 0.5802 | 0.6451 | 0.7803 | 0.020* | |
H10C | 0.4203 | 0.7384 | 0.7834 | 0.020* | |
C10 | 0.49822 (17) | 0.70736 (13) | 0.71391 (4) | 0.0131 (2) | |
H10 | 0.4307 | 0.6198 | 0.7070 | 0.016* | |
C11 | 0.68581 (19) | 0.70458 (16) | 0.68855 (5) | 0.0175 (3) | |
H11A | 0.7301 | 0.8008 | 0.6851 | 0.021* | |
H11B | 0.7720 | 0.6545 | 0.7101 | 0.021* | |
C12 | 0.68628 (19) | 0.63705 (14) | 0.63820 (5) | 0.0165 (3) | |
C13 | 0.6299 (2) | 0.70899 (16) | 0.59619 (5) | 0.0199 (3) | |
H13 | 0.5899 | 0.8021 | 0.5990 | 0.024* | |
C14 | 0.6322 (2) | 0.6449 (2) | 0.55034 (6) | 0.0310 (4) | |
H14 | 0.5924 | 0.6939 | 0.5219 | 0.037* | |
C15 | 0.6927 (3) | 0.5092 (2) | 0.54597 (7) | 0.0399 (5) | |
H15 | 0.6951 | 0.4658 | 0.5145 | 0.048* | |
C16 | 0.7488 (3) | 0.43792 (18) | 0.58701 (8) | 0.0391 (5) | |
H16 | 0.7901 | 0.3452 | 0.5839 | 0.047* | |
C17 | 0.7457 (2) | 0.50079 (16) | 0.63329 (7) | 0.0261 (3) | |
H17 | 0.7841 | 0.4507 | 0.6616 | 0.031* | |
C18 | 0.38577 (18) | 0.83238 (13) | 0.69813 (4) | 0.0132 (2) | |
O18 | 0.41380 (14) | 0.94414 (10) | 0.71910 (3) | 0.0177 (2) | |
N20 | 0.26742 (16) | 0.81851 (11) | 0.66147 (4) | 0.0138 (2) | |
C20 | 0.16322 (18) | 0.93995 (13) | 0.64568 (5) | 0.0140 (3) | |
H20 | 0.0887 | 0.9764 | 0.6736 | 0.017* | |
C22 | 0.1285 (2) | 0.74806 (14) | 0.58840 (5) | 0.0187 (3) | |
H22A | 0.0379 | 0.6835 | 0.5744 | 0.022* | |
H22B | 0.2248 | 0.7646 | 0.5636 | 0.022* | |
C21 | 0.0392 (2) | 0.88425 (14) | 0.60427 (5) | 0.0183 (3) | |
H21A | −0.0852 | 0.8679 | 0.6167 | 0.022* | |
H21B | 0.0335 | 0.9501 | 0.5763 | 0.022* | |
C23 | 0.20798 (19) | 0.69142 (14) | 0.63610 (5) | 0.0160 (3) | |
H23A | 0.1153 | 0.6413 | 0.6556 | 0.019* | |
H23B | 0.3115 | 0.6289 | 0.6295 | 0.019* | |
C24 | 0.28494 (18) | 1.05274 (13) | 0.62516 (5) | 0.0143 (2) | |
O24 | 0.42220 (15) | 1.02895 (11) | 0.60149 (4) | 0.0226 (2) | |
N30 | 0.22132 (17) | 1.18119 (12) | 0.63443 (4) | 0.0175 (2) | |
H30 | 0.1378 | 1.1928 | 0.6573 | 0.021* | |
C30 | 0.2878 (2) | 1.29938 (15) | 0.60763 (5) | 0.0206 (3) | |
H30A | 0.4206 | 1.2903 | 0.6031 | 0.025* | |
H30B | 0.2650 | 1.3841 | 0.6272 | 0.025* | |
C31 | 0.1982 (2) | 1.31382 (14) | 0.55761 (5) | 0.0183 (3) | |
O31 | 0.09911 (18) | 1.22970 (12) | 0.53927 (4) | 0.0269 (2) | |
O32 | 0.24639 (17) | 1.43362 (11) | 0.53707 (4) | 0.0248 (2) | |
C32 | 0.1767 (3) | 1.4570 (2) | 0.48750 (6) | 0.0367 (4) | |
H32A | 0.2270 | 1.3875 | 0.4650 | 0.055* | |
H32B | 0.2121 | 1.5496 | 0.4763 | 0.055* | |
H32C | 0.0441 | 1.4498 | 0.4878 | 0.055* | |
O1 | 0.81122 (14) | 0.92109 (10) | 0.78001 (4) | 0.0195 (2) | |
H1 | 0.9029 | 0.8722 | 0.7787 | 0.023* | |
H2 | 0.8324 | 0.9851 | 0.7638 | 0.023* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl | 0.01806 (16) | 0.01737 (15) | 0.03278 (18) | −0.00004 (13) | 0.00761 (14) | −0.00212 (13) |
N10 | 0.0160 (5) | 0.0120 (5) | 0.0123 (5) | 0.0004 (4) | −0.0018 (4) | 0.0010 (4) |
C10 | 0.0151 (5) | 0.0122 (5) | 0.0119 (5) | 0.0002 (5) | −0.0010 (5) | 0.0010 (5) |
C11 | 0.0148 (6) | 0.0220 (7) | 0.0157 (6) | −0.0005 (5) | 0.0005 (5) | −0.0006 (5) |
C12 | 0.0135 (5) | 0.0168 (6) | 0.0191 (6) | −0.0028 (5) | 0.0032 (5) | −0.0043 (5) |
C13 | 0.0174 (6) | 0.0246 (7) | 0.0178 (6) | −0.0043 (6) | 0.0012 (5) | −0.0029 (5) |
C14 | 0.0218 (7) | 0.0511 (10) | 0.0202 (7) | −0.0096 (8) | 0.0021 (6) | −0.0081 (7) |
C15 | 0.0281 (8) | 0.0539 (12) | 0.0375 (9) | −0.0133 (9) | 0.0105 (7) | −0.0320 (9) |
C16 | 0.0241 (8) | 0.0245 (8) | 0.0686 (13) | −0.0067 (7) | 0.0142 (9) | −0.0251 (9) |
C17 | 0.0175 (6) | 0.0179 (7) | 0.0429 (9) | −0.0013 (6) | 0.0049 (7) | −0.0024 (6) |
C18 | 0.0145 (5) | 0.0123 (5) | 0.0127 (5) | −0.0018 (5) | 0.0024 (5) | 0.0026 (4) |
O18 | 0.0226 (5) | 0.0122 (4) | 0.0182 (4) | −0.0010 (4) | −0.0045 (4) | 0.0000 (4) |
N20 | 0.0166 (5) | 0.0092 (5) | 0.0157 (5) | −0.0006 (4) | −0.0014 (4) | 0.0010 (4) |
C20 | 0.0162 (6) | 0.0119 (6) | 0.0140 (5) | 0.0011 (5) | 0.0000 (5) | 0.0023 (4) |
C22 | 0.0217 (7) | 0.0187 (6) | 0.0157 (6) | −0.0025 (5) | −0.0052 (5) | −0.0013 (5) |
C21 | 0.0182 (6) | 0.0174 (6) | 0.0194 (6) | −0.0035 (5) | −0.0053 (5) | 0.0025 (5) |
C23 | 0.0174 (6) | 0.0124 (6) | 0.0183 (6) | −0.0031 (5) | −0.0027 (5) | −0.0003 (5) |
C24 | 0.0170 (6) | 0.0130 (6) | 0.0130 (5) | −0.0010 (5) | −0.0026 (5) | 0.0017 (5) |
O24 | 0.0220 (5) | 0.0192 (5) | 0.0266 (5) | −0.0012 (4) | 0.0077 (4) | 0.0041 (4) |
N30 | 0.0227 (6) | 0.0128 (5) | 0.0169 (5) | −0.0005 (5) | 0.0011 (4) | 0.0021 (4) |
C30 | 0.0268 (7) | 0.0137 (6) | 0.0214 (6) | −0.0047 (6) | −0.0040 (5) | 0.0038 (5) |
C31 | 0.0215 (6) | 0.0153 (6) | 0.0181 (6) | 0.0031 (6) | 0.0039 (5) | 0.0006 (5) |
O31 | 0.0353 (6) | 0.0221 (5) | 0.0233 (5) | −0.0015 (5) | −0.0060 (5) | −0.0025 (4) |
O32 | 0.0299 (6) | 0.0211 (5) | 0.0233 (5) | 0.0000 (5) | −0.0007 (5) | 0.0089 (4) |
C32 | 0.0483 (11) | 0.0399 (9) | 0.0218 (7) | 0.0074 (9) | 0.0005 (7) | 0.0101 (7) |
O1 | 0.0186 (5) | 0.0172 (4) | 0.0227 (5) | 0.0001 (4) | 0.0005 (4) | 0.0003 (4) |
N10—C10 | 1.4947 (16) | C20—C21 | 1.5441 (18) |
N10—H10A | 0.9100 | C20—H20 | 1.0000 |
N10—H10B | 0.9100 | C22—C23 | 1.5209 (18) |
N10—H10C | 0.9100 | C22—C21 | 1.533 (2) |
C10—C18 | 1.5265 (17) | C22—H22A | 0.9900 |
C10—C11 | 1.5442 (18) | C22—H22B | 0.9900 |
C10—H10 | 1.0000 | C21—H21A | 0.9900 |
C11—C12 | 1.5125 (18) | C21—H21B | 0.9900 |
C11—H11A | 0.9900 | C23—H23A | 0.9900 |
C11—H11B | 0.9900 | C23—H23B | 0.9900 |
C12—C17 | 1.394 (2) | C24—O24 | 1.2197 (17) |
C12—C13 | 1.397 (2) | C24—N30 | 1.3509 (17) |
C13—C14 | 1.388 (2) | N30—C30 | 1.4397 (17) |
C13—H13 | 0.9500 | N30—H30 | 0.8800 |
C14—C15 | 1.391 (3) | C30—C31 | 1.5144 (19) |
C14—H14 | 0.9500 | C30—H30A | 0.9900 |
C15—C16 | 1.372 (3) | C30—H30B | 0.9900 |
C15—H15 | 0.9500 | C31—O31 | 1.2006 (19) |
C16—C17 | 1.394 (3) | C31—O32 | 1.3329 (17) |
C16—H16 | 0.9500 | O32—C32 | 1.456 (2) |
C17—H17 | 0.9500 | C32—H32A | 0.9800 |
C18—O18 | 1.2381 (16) | C32—H32B | 0.9800 |
C18—N20 | 1.3289 (17) | C32—H32C | 0.9800 |
N20—C20 | 1.4666 (16) | O1—H1 | 0.825 |
N20—C23 | 1.4745 (17) | O1—H2 | 0.775 |
C20—C24 | 1.5176 (18) | ||
C10—N10—H10A | 109.5 | N20—C20—H20 | 110.4 |
C10—N10—H10B | 109.5 | C24—C20—H20 | 110.4 |
H10A—N10—H10B | 109.5 | C21—C20—H20 | 110.4 |
C10—N10—H10C | 109.5 | C23—C22—C21 | 103.65 (11) |
H10A—N10—H10C | 109.5 | C23—C22—H22A | 111.0 |
H10B—N10—H10C | 109.5 | C21—C22—H22A | 111.0 |
N10—C10—C18 | 105.90 (10) | C23—C22—H22B | 111.0 |
N10—C10—C11 | 107.80 (10) | C21—C22—H22B | 111.0 |
C18—C10—C11 | 112.04 (10) | H22A—C22—H22B | 109.0 |
N10—C10—H10 | 110.3 | C22—C21—C20 | 104.43 (11) |
C18—C10—H10 | 110.3 | C22—C21—H21A | 110.9 |
C11—C10—H10 | 110.3 | C20—C21—H21A | 110.9 |
C12—C11—C10 | 114.26 (11) | C22—C21—H21B | 110.9 |
C12—C11—H11A | 108.7 | C20—C21—H21B | 110.9 |
C10—C11—H11A | 108.7 | H21A—C21—H21B | 108.9 |
C12—C11—H11B | 108.7 | N20—C23—C22 | 102.16 (10) |
C10—C11—H11B | 108.7 | N20—C23—H23A | 111.3 |
H11A—C11—H11B | 107.6 | C22—C23—H23A | 111.3 |
C17—C12—C13 | 119.06 (14) | N20—C23—H23B | 111.3 |
C17—C12—C11 | 119.64 (14) | C22—C23—H23B | 111.3 |
C13—C12—C11 | 121.30 (13) | H23A—C23—H23B | 109.2 |
C14—C13—C12 | 120.25 (15) | O24—C24—N30 | 123.99 (13) |
C14—C13—H13 | 119.9 | O24—C24—C20 | 123.20 (12) |
C12—C13—H13 | 119.9 | N30—C24—C20 | 112.77 (12) |
C13—C14—C15 | 120.05 (18) | C24—N30—C30 | 121.16 (12) |
C13—C14—H14 | 120.0 | C24—N30—H30 | 119.4 |
C15—C14—H14 | 120.0 | C30—N30—H30 | 119.4 |
C16—C15—C14 | 120.10 (16) | N30—C30—C31 | 112.10 (12) |
C16—C15—H15 | 120.0 | N30—C30—H30A | 109.2 |
C14—C15—H15 | 120.0 | C31—C30—H30A | 109.2 |
C15—C16—C17 | 120.34 (17) | N30—C30—H30B | 109.2 |
C15—C16—H16 | 119.8 | C31—C30—H30B | 109.2 |
C17—C16—H16 | 119.8 | H30A—C30—H30B | 107.9 |
C16—C17—C12 | 120.20 (17) | O31—C31—O32 | 125.29 (13) |
C16—C17—H17 | 119.9 | O31—C31—C30 | 124.98 (13) |
C12—C17—H17 | 119.9 | O32—C31—C30 | 109.73 (12) |
O18—C18—N20 | 122.73 (12) | C31—O32—C32 | 115.22 (13) |
O18—C18—C10 | 118.15 (11) | O32—C32—H32A | 109.5 |
N20—C18—C10 | 119.07 (11) | O32—C32—H32B | 109.5 |
C18—N20—C20 | 118.75 (11) | H32A—C32—H32B | 109.5 |
C18—N20—C23 | 128.88 (11) | O32—C32—H32C | 109.5 |
C20—N20—C23 | 112.05 (10) | H32A—C32—H32C | 109.5 |
N20—C20—C24 | 111.86 (11) | H32B—C32—H32C | 109.5 |
N20—C20—C21 | 104.05 (10) | H1—O1—H2 | 105.56 |
C24—C20—C21 | 109.51 (11) | ||
N10—C10—C11—C12 | 158.2 (1) | C23—N20—C20—C24 | −122.61 (12) |
C18—C10—C11—C12 | −85.66 (14) | C18—N20—C20—C21 | −178.58 (11) |
C10—C11—C12—C17 | −99.94 (15) | C23—N20—C20—C21 | −4.49 (14) |
C10—C11—C12—C13 | 80.71 (17) | C23—C22—C21—C20 | 34.16 (14) |
C17—C12—C13—C14 | 0.4 (2) | N20—C20—C21—C22 | −18.6 (1) |
C11—C12—C13—C14 | 179.76 (13) | C24—C20—C21—C22 | 101.18 (12) |
C12—C13—C14—C15 | −0.8 (2) | C18—N20—C23—C22 | −160.99 (13) |
C13—C14—C15—C16 | 0.5 (3) | C20—N20—C23—C22 | 25.66 (14) |
C14—C15—C16—C17 | 0.0 (3) | C21—C22—C23—N20 | −36.02 (13) |
C15—C16—C17—C12 | −0.4 (3) | N20—C20—C24—O24 | 35.04 (17) |
C13—C12—C17—C16 | 0.1 (2) | C21—C20—C24—O24 | −79.78 (16) |
C11—C12—C17—C16 | −179.22 (14) | N20—C20—C24—N30 | −147.2 (1) |
N10—C10—C18—O18 | 34.80 (15) | C21—C20—C24—N30 | 98.00 (13) |
C11—C10—C18—O18 | −82.47 (14) | O24—C24—N30—C30 | 14.4 (2) |
N10—C10—C18—N20 | −147.7 (1) | C20—C24—N30—C30 | −163.4 (1) |
C11—C10—C18—N20 | 95.02 (14) | C24—N30—C30—C31 | 80.9 (2) |
O18—C18—N20—C20 | −1.09 (19) | N30—C30—C31—O31 | −8.2 (2) |
C10—C18—N20—C20 | −178.5 (1) | N30—C30—C31—O32 | 172.0 (1) |
O18—C18—N20—C23 | −174.05 (12) | O31—C31—O32—C32 | −3.0 (2) |
C10—C18—N20—C23 | 8.58 (19) | C30—C31—O32—C32 | 176.89 (14) |
C18—N20—C20—C24 | 63.3 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N10—H10A···O1 | 0.91 | 1.96 | 2.845 (2) | 166 |
N10—H10C···Cl | 0.91 | 2.31 | 3.112 (1) | 147 |
N10—H10B···O18i | 0.91 | 1.94 | 2.755 (1) | 148 |
O1—H2···Clii | 0.77 | 2.43 | 3.201 (1) | 177 |
N30—H30···Cliii | 0.88 | 2.43 | 3.299 (1) | 171 |
O1—H1···Cliv | 0.82 | 2.33 | 3.139 (1) | 165 |
Symmetry codes: (i) −x+1, y−1/2, −z+3/2; (ii) −x+1, y+1/2, −z+3/2; (iii) −x, y+1/2, −z+3/2; (iv) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C17H24N3O4+·Cl−·H2O |
Mr | 387.86 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 90 |
a, b, c (Å) | 7.3707 (5), 9.6667 (7), 27.099 (2) |
V (Å3) | 1930.8 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.23 |
Crystal size (mm) | 0.40 × 0.35 × 0.35 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.874, 0.923 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 23047, 4553, 4540 |
Rint | 0.020 |
(sin θ/λ)max (Å−1) | 0.658 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.032, 0.088, 0.85 |
No. of reflections | 4553 |
No. of parameters | 237 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.46, −0.21 |
Absolute structure | Flack (1983), 1920 Friedel pairs |
Absolute structure parameter | 0.03 (4) |
Computer programs: SMART (Bruker, 1998), SAINT-Plus (Bruker, 1998), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
N10—H10A···O1 | 0.91 | 1.96 | 2.845 (2) | 166 |
N10—H10C···Cl | 0.91 | 2.31 | 3.112 (1) | 147 |
N10—H10B···O18i | 0.91 | 1.94 | 2.755 (1) | 148 |
O1—H2···Clii | 0.77 | 2.43 | 3.201 (1) | 177 |
N30—H30···Cliii | 0.88 | 2.43 | 3.299 (1) | 171 |
O1—H1···Cliv | 0.82 | 2.33 | 3.139 (1) | 165 |
Symmetry codes: (i) −x+1, y−1/2, −z+3/2; (ii) −x+1, y+1/2, −z+3/2; (iii) −x, y+1/2, −z+3/2; (iv) x+1, y, z. |
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
The β-turn structures were formed at D-Pro residue in a Gramicidin S and its analogue (Doi et al., 2001; Yamada et al., 2002; Llamas-Saiz, et al., 2007), and a motif including D-Pro promoted β-hairpin in the protein GB1 analogue (Espinosa & Gellman, 2000). A tripeptide motif of Boc–Phe–D-Pro–Gly–OMe (Boc = t-butyloxycarbonyl; OMe = methylester) was designed from these peptides, and the β-turn structure was elucidated (Doi et al., 2007). Moreover, the CD spectra of Gramicidin S analogues suggested that the chiral combination of Phe and Pro residues contributes to the β-turn formation (Tamaki et al., 1985). Title peptide (I) was designed to highlight the chirality of the Phe residue in this tripeptide β-turn motif.
The molecular structure of (I) is shown in Fig. 1. The peptide is a chloride salt and its N-terminal (N10 atom) is protonated. The peptide molecule is somewhat extended, but the structure is not classified to any typical secondary structures from torsion angles. The Pro residue shows a ring puckering with amplitude of Q2 = 0.361 (2) Å and phase of ϕ2 = 293.1 (2) ° (Cremer & Pople, 1975), which is slightly different from those of the β-turn structure of Boc–Phe–D-Pro–Gly–OMe (Doi et al., 2007).
A peptide-peptide hydrogen bond is formed between N10 and O18 atoms. This interaction makes the molecular arrangement propagated along the b axis, but no sheet structure is created (Fig. 2). Molecular packing is stabilized by the interactions with chloride ion (Cl) and water molecule (O1).
CD spectra of (I) showed no clear proof of special structures existed in acetonitril solution (data not shown), and the structure of (I) was somewhat extended. In contrast to the β-turn structure of the diastereomeric tripeptide (Boc–Phe–D-Pro–Gly–OMe), these results indicate that the chirality of Phe different from that of Pro is important for folding of this tripeptide motif.