organic compounds
Methyl 3-O-α-L-fucopyranosyl α-D-galactopyranoside: a synchrotron study
aDepartment of Material and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden, and bDepartment of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
*Correspondence e-mail: lars.eriksson@mmk.su.se
The title compound, C13H24O10 is the methyl glycoside of a structural element α-L-Fucp-(1→ 3)-α-D-Galp making up two thirds of the repeating unit in the capsular polysaccharide of Klebsiella K63. The conformation of the title compound is described by the glycosidic torsion angles φH = 55 (1)° and ψH = −24 (1)°. The hydroxymethyl group in the galactose residue is present in the gauche–trans conformation. In the crystal, O—H⋯O hydrogen bonds connect the disaccharide units into chains along the a-axis direction and further hydrogen bonds cross-link the chains.
Related literature
The capsular polysaccharide (CPS) of Klebsiella K63 contains a repeating unit consisting of → 3)-α-D-GalpA–(1 → 3)-α-L-Fucp-(1 → 3)-α-D-Galp-(1 →, see: Joseleau & Marais (1979). For an investigation of the CPS S-156 from Klebsiella pneumoniae ATCC 316 46, see: Johansson et al. (1994) and of the CPS from Klebsiella pneumoniae I-1507, see: Guetta et al. (2003). For a fiber X-ray diffraction study of the Klebsiella K63 CPS, see: Elloway et al. (1980). For the synthesis, see: Baumann et al. (1988).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: MARCCD (Marresearch, 2010); cell CrysAlis RED (Oxford Diffraction, 2008); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: PLATON (Spek, 2009).
Supporting information
10.1107/S1600536812002279/hb6569sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536812002279/hb6569Isup2.hkl
The synthesis of (I) was described by Baumann et al. (1988) in which the fucose and galactose residues have the L and D absolute configurations, respectively. The compound was crystallized by slow evaporation of a mixture of water and ethanol (1:1) at ambient temperature.
The hydrogen atoms were refined in riding mode with Uiso(H) = 1.5Ueq(X), where X = C or O. The coverage at 0.8 Å resolution = 0.738 but already at 0.9 Å resolution the coverage has increased to 0.922 and at 1.0 Å resolution the coverage ~0.995. The with reflection data up to 1.0 Å resolution converged at R1 = 0.0466. It should be noted that the reflection data diminishes at high resolution as shown in Fig 2; thus the low coverage to 0.8 or 0.9 Å is of minor importance.
Data collection: MARCCD (Marresearch, 2010); cell
CrysAlis RED (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: PLATON (Spek, 2009).C13H24O10 | Z = 4 |
Mr = 340.32 | F(000) = 728 |
Orthorhombic, P212121 | Dx = 1.539 Mg m−3 |
Hall symbol: P 2ac 2ab | Synchrotron radiation, λ = 0.907 Å |
a = 4.78478 (11) Å | µ = 0.13 mm−1 |
b = 15.7859 (5) Å | T = 100 K |
c = 19.4401 (5) Å | Prism, colorless |
V = 1468.36 (7) Å3 | 0.03 × 0.01 × 0.01 mm |
Marresearch MARCCD 165 diffractometer | 975 reflections with I > 2σ(I) |
Radiation source: I911, Maxlab | Rint = 0.117 |
Si(111) monochromator | θmax = 30.1°, θmin = 3.1° |
Detector resolution: 0.0806 pixels mm-1 | h = −5→5 |
ϕ scans | k = −17→17 |
7469 measured reflections | l = −20→20 |
1162 independent reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.060 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.177 | H-atom parameters constrained |
S = 1.09 | w = 1/[σ2(Fo2) + (0.1211P)2 + 0.7072P] where P = (Fo2 + 2Fc2)/3 |
1162 reflections | (Δ/σ)max < 0.001 |
216 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.27 e Å−3 |
C13H24O10 | V = 1468.36 (7) Å3 |
Mr = 340.32 | Z = 4 |
Orthorhombic, P212121 | Synchrotron radiation, λ = 0.907 Å |
a = 4.78478 (11) Å | µ = 0.13 mm−1 |
b = 15.7859 (5) Å | T = 100 K |
c = 19.4401 (5) Å | 0.03 × 0.01 × 0.01 mm |
Marresearch MARCCD 165 diffractometer | 975 reflections with I > 2σ(I) |
7469 measured reflections | Rint = 0.117 |
1162 independent reflections | θmax = 30.1° |
R[F2 > 2σ(F2)] = 0.060 | 0 restraints |
wR(F2) = 0.177 | H-atom parameters constrained |
S = 1.09 | Δρmax = 0.30 e Å−3 |
1162 reflections | Δρmin = −0.27 e Å−3 |
216 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
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 | ||
C1F | 0.2242 (15) | 0.5346 (4) | 0.5260 (3) | 0.0359 (16) | |
H1F | 0.0917 | 0.5802 | 0.5114 | 0.054* | |
C2F | 0.3048 (14) | 0.4827 (5) | 0.4636 (3) | 0.0409 (17) | |
H2F | 0.1270 | 0.4633 | 0.4416 | 0.061* | |
C3F | 0.4713 (14) | 0.4025 (4) | 0.4827 (3) | 0.0394 (17) | |
H3F | 0.6577 | 0.4217 | 0.4999 | 0.059* | |
C4F | 0.3298 (15) | 0.3548 (5) | 0.5419 (3) | 0.0382 (17) | |
H4F | 0.4571 | 0.3089 | 0.5585 | 0.057* | |
C5F | 0.2588 (15) | 0.4126 (4) | 0.6012 (3) | 0.0403 (17) | |
H5F | 0.4368 | 0.4347 | 0.6214 | 0.060* | |
O5F | 0.0941 (9) | 0.4845 (3) | 0.5765 (2) | 0.0393 (12) | |
C6F | 0.0937 (17) | 0.3710 (5) | 0.6571 (3) | 0.0465 (19) | |
H6F1 | 0.0533 | 0.4124 | 0.6933 | 0.070* | |
H6F2 | 0.2017 | 0.3240 | 0.6764 | 0.070* | |
H6F3 | −0.0822 | 0.3494 | 0.6381 | 0.070* | |
O2F | 0.4489 (10) | 0.5325 (3) | 0.4138 (2) | 0.0430 (13) | |
H2F1 | 0.5624 | 0.5648 | 0.4338 | 0.065* | |
O3F | 0.5214 (11) | 0.3485 (3) | 0.4262 (2) | 0.0458 (13) | |
H3F1 | 0.3725 | 0.3417 | 0.4040 | 0.069* | |
O4F | 0.0806 (9) | 0.3171 (3) | 0.5133 (3) | 0.0430 (13) | |
H4F1 | 0.0532 | 0.2697 | 0.5316 | 0.065* | |
C1G | 0.6262 (16) | 0.7690 (5) | 0.6550 (3) | 0.0400 (17) | |
H1G | 0.7796 | 0.8113 | 0.6487 | 0.060* | |
C2G | 0.6339 (14) | 0.7069 (4) | 0.5935 (3) | 0.0371 (17) | |
H2G | 0.8264 | 0.6823 | 0.5909 | 0.056* | |
C3G | 0.4279 (14) | 0.6336 (4) | 0.6047 (3) | 0.0362 (16) | |
H3G | 0.2321 | 0.6554 | 0.6017 | 0.054* | |
C4G | 0.4759 (15) | 0.5952 (5) | 0.6746 (4) | 0.0406 (18) | |
H4G | 0.3289 | 0.5514 | 0.6831 | 0.061* | |
C5G | 0.4618 (15) | 0.6608 (4) | 0.7312 (4) | 0.0420 (18) | |
H5G | 0.2701 | 0.6860 | 0.7328 | 0.063* | |
C6G | 0.5295 (18) | 0.6222 (5) | 0.7996 (3) | 0.0463 (19) | |
H6G1 | 0.4176 | 0.5700 | 0.8059 | 0.069* | |
H6G2 | 0.7295 | 0.6062 | 0.8006 | 0.069* | |
O1G | 0.3648 (10) | 0.8128 (3) | 0.6509 (2) | 0.0434 (13) | |
O2G | 0.5808 (10) | 0.7497 (3) | 0.5311 (2) | 0.0436 (13) | |
H2G1 | 0.7044 | 0.7370 | 0.5022 | 0.065* | |
O3G | 0.4759 (10) | 0.5731 (3) | 0.5507 (2) | 0.0412 (12) | |
O4G | 0.7492 (10) | 0.5552 (3) | 0.6797 (2) | 0.0444 (13) | |
H4G1 | 0.7904 | 0.5329 | 0.6418 | 0.067* | |
O5G | 0.6680 (10) | 0.7279 (3) | 0.7175 (2) | 0.0418 (13) | |
O6G | 0.4725 (10) | 0.6796 (3) | 0.8553 (2) | 0.0446 (13) | |
H6G | 0.5970 | 0.6748 | 0.8855 | 0.067* | |
C7 | 0.3647 (18) | 0.8825 (5) | 0.6975 (3) | 0.049 (2) | |
H7A | 0.3842 | 0.8615 | 0.7447 | 0.073* | |
H7B | 0.1885 | 0.9137 | 0.6931 | 0.073* | |
H7C | 0.5213 | 0.9202 | 0.6867 | 0.073* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1F | 0.026 (3) | 0.053 (4) | 0.029 (3) | 0.002 (3) | −0.004 (3) | −0.006 (3) |
C2F | 0.021 (3) | 0.061 (4) | 0.041 (4) | −0.004 (3) | −0.012 (3) | 0.005 (4) |
C3F | 0.025 (3) | 0.058 (4) | 0.035 (4) | −0.001 (4) | −0.003 (3) | −0.007 (3) |
C4F | 0.028 (4) | 0.051 (4) | 0.035 (4) | −0.004 (3) | −0.007 (3) | −0.005 (3) |
C5F | 0.024 (3) | 0.054 (4) | 0.044 (4) | 0.005 (4) | −0.003 (3) | 0.006 (3) |
O5F | 0.023 (2) | 0.057 (3) | 0.038 (3) | 0.000 (2) | 0.002 (2) | 0.002 (2) |
C6F | 0.038 (4) | 0.062 (5) | 0.040 (4) | 0.007 (4) | 0.001 (3) | 0.000 (4) |
O2F | 0.030 (3) | 0.061 (3) | 0.038 (2) | −0.004 (2) | 0.004 (2) | 0.000 (2) |
O3F | 0.026 (3) | 0.067 (3) | 0.044 (3) | 0.000 (3) | −0.002 (2) | −0.001 (2) |
O4F | 0.023 (3) | 0.058 (3) | 0.048 (3) | −0.005 (2) | 0.000 (2) | −0.001 (2) |
C1G | 0.036 (4) | 0.051 (4) | 0.032 (4) | 0.005 (4) | 0.001 (3) | 0.007 (3) |
C2G | 0.020 (3) | 0.059 (4) | 0.032 (3) | 0.006 (3) | 0.001 (3) | 0.000 (3) |
C3G | 0.020 (3) | 0.049 (4) | 0.040 (4) | 0.001 (3) | −0.012 (3) | −0.003 (3) |
C4G | 0.021 (3) | 0.051 (4) | 0.050 (4) | 0.005 (3) | −0.007 (3) | 0.000 (4) |
C5G | 0.025 (4) | 0.059 (5) | 0.043 (4) | 0.002 (4) | −0.002 (3) | 0.002 (3) |
C6G | 0.047 (5) | 0.055 (4) | 0.037 (4) | 0.006 (4) | −0.002 (4) | −0.004 (4) |
O1G | 0.029 (3) | 0.059 (3) | 0.042 (3) | 0.006 (3) | −0.006 (2) | 0.006 (2) |
O2G | 0.023 (3) | 0.071 (3) | 0.038 (2) | 0.008 (3) | 0.002 (2) | 0.008 (3) |
O3G | 0.025 (3) | 0.058 (3) | 0.041 (3) | 0.000 (2) | −0.009 (2) | −0.002 (2) |
O4G | 0.031 (3) | 0.063 (3) | 0.040 (3) | 0.010 (3) | 0.003 (2) | −0.006 (2) |
O5G | 0.028 (3) | 0.061 (3) | 0.037 (3) | −0.005 (2) | −0.002 (2) | 0.000 (2) |
O6G | 0.029 (3) | 0.069 (3) | 0.036 (3) | −0.003 (3) | −0.002 (2) | −0.004 (3) |
C7 | 0.042 (4) | 0.068 (5) | 0.036 (4) | 0.010 (4) | −0.008 (3) | −0.004 (4) |
C1F—O5F | 1.406 (8) | C1G—C2G | 1.546 (9) |
C1F—O3G | 1.432 (8) | C1G—H1G | 1.0000 |
C1F—C2F | 1.515 (9) | C2G—O2G | 1.414 (8) |
C1F—H1F | 1.0000 | C2G—C3G | 1.535 (9) |
C2F—O2F | 1.425 (8) | C2G—H2G | 1.0000 |
C2F—C3F | 1.541 (10) | C3G—O3G | 1.438 (8) |
C2F—H2F | 1.0000 | C3G—C4G | 1.505 (9) |
C3F—O3F | 1.411 (8) | C3G—H3G | 1.0000 |
C3F—C4F | 1.532 (10) | C4G—O4G | 1.456 (9) |
C3F—H3F | 1.0000 | C4G—C5G | 1.513 (10) |
C4F—O4F | 1.444 (8) | C4G—H4G | 1.0000 |
C4F—C5F | 1.509 (9) | C5G—O5G | 1.471 (8) |
C4F—H4F | 1.0000 | C5G—C6G | 1.498 (10) |
C5F—O5F | 1.462 (8) | C5G—H5G | 1.0000 |
C5F—C6F | 1.495 (10) | C6G—O6G | 1.437 (8) |
C5F—H5F | 1.0000 | C6G—H6G1 | 0.9900 |
C6F—H6F1 | 0.9800 | C6G—H6G2 | 0.9900 |
C6F—H6F2 | 0.9800 | O1G—C7 | 1.424 (8) |
C6F—H6F3 | 0.9800 | O2G—H2G1 | 0.8400 |
O2F—H2F1 | 0.8400 | O4G—H4G1 | 0.8400 |
O3F—H3F1 | 0.8400 | O6G—H6G | 0.8400 |
O4F—H4F1 | 0.8400 | C7—H7A | 0.9800 |
C1G—O5G | 1.392 (8) | C7—H7B | 0.9800 |
C1G—O1G | 1.431 (9) | C7—H7C | 0.9800 |
O5F—C1F—O3G | 112.2 (5) | O1G—C1G—H1G | 108.2 |
O5F—C1F—C2F | 111.6 (5) | C2G—C1G—H1G | 108.2 |
O3G—C1F—C2F | 106.5 (5) | O2G—C2G—C3G | 111.5 (5) |
O5F—C1F—H1F | 108.8 | O2G—C2G—C1G | 110.9 (5) |
O3G—C1F—H1F | 108.8 | C3G—C2G—C1G | 110.7 (5) |
C2F—C1F—H1F | 108.8 | O2G—C2G—H2G | 107.9 |
O2F—C2F—C1F | 111.7 (6) | C3G—C2G—H2G | 107.9 |
O2F—C2F—C3F | 111.5 (5) | C1G—C2G—H2G | 107.9 |
C1F—C2F—C3F | 112.5 (5) | O3G—C3G—C4G | 111.5 (5) |
O2F—C2F—H2F | 106.9 | O3G—C3G—C2G | 107.1 (5) |
C1F—C2F—H2F | 106.9 | C4G—C3G—C2G | 109.5 (5) |
C3F—C2F—H2F | 106.9 | O3G—C3G—H3G | 109.6 |
O3F—C3F—C4F | 111.3 (6) | C4G—C3G—H3G | 109.6 |
O3F—C3F—C2F | 113.4 (5) | C2G—C3G—H3G | 109.6 |
C4F—C3F—C2F | 110.9 (6) | O4G—C4G—C3G | 111.9 (6) |
O3F—C3F—H3F | 107.0 | O4G—C4G—C5G | 106.7 (6) |
C4F—C3F—H3F | 107.0 | C3G—C4G—C5G | 112.0 (6) |
C2F—C3F—H3F | 107.0 | O4G—C4G—H4G | 108.7 |
O4F—C4F—C5F | 110.9 (6) | C3G—C4G—H4G | 108.7 |
O4F—C4F—C3F | 106.1 (5) | C5G—C4G—H4G | 108.7 |
C5F—C4F—C3F | 112.1 (6) | O5G—C5G—C6G | 108.0 (6) |
O4F—C4F—H4F | 109.2 | O5G—C5G—C4G | 109.2 (6) |
C5F—C4F—H4F | 109.2 | C6G—C5G—C4G | 111.0 (6) |
C3F—C4F—H4F | 109.2 | O5G—C5G—H5G | 109.5 |
O5F—C5F—C6F | 107.1 (6) | C6G—C5G—H5G | 109.5 |
O5F—C5F—C4F | 109.8 (5) | C4G—C5G—H5G | 109.5 |
C6F—C5F—C4F | 114.1 (6) | O6G—C6G—C5G | 111.7 (6) |
O5F—C5F—H5F | 108.5 | O6G—C6G—H6G1 | 109.3 |
C6F—C5F—H5F | 108.5 | C5G—C6G—H6G1 | 109.3 |
C4F—C5F—H5F | 108.5 | O6G—C6G—H6G2 | 109.3 |
C1F—O5F—C5F | 115.3 (5) | C5G—C6G—H6G2 | 109.3 |
C5F—C6F—H6F1 | 109.5 | H6G1—C6G—H6G2 | 107.9 |
C5F—C6F—H6F2 | 109.5 | C7—O1G—C1G | 109.8 (5) |
H6F1—C6F—H6F2 | 109.5 | C2G—O2G—H2G1 | 109.5 |
C5F—C6F—H6F3 | 109.5 | C1F—O3G—C3G | 113.1 (5) |
H6F1—C6F—H6F3 | 109.5 | C4G—O4G—H4G1 | 109.5 |
H6F2—C6F—H6F3 | 109.5 | C1G—O5G—C5G | 113.4 (5) |
C2F—O2F—H2F1 | 109.5 | C6G—O6G—H6G | 109.5 |
C3F—O3F—H3F1 | 109.5 | O1G—C7—H7A | 109.5 |
C4F—O4F—H4F1 | 109.5 | O1G—C7—H7B | 109.5 |
O5G—C1G—O1G | 113.5 (5) | H7A—C7—H7B | 109.5 |
O5G—C1G—C2G | 112.0 (5) | O1G—C7—H7C | 109.5 |
O1G—C1G—C2G | 106.6 (5) | H7A—C7—H7C | 109.5 |
O5G—C1G—H1G | 108.2 | H7B—C7—H7C | 109.5 |
O5F—C1F—C2F—O2F | −177.1 (5) | O2G—C2G—C3G—O3G | 64.1 (6) |
O3G—C1F—C2F—O2F | −54.4 (7) | C1G—C2G—C3G—O3G | −172.1 (5) |
O5F—C1F—C2F—C3F | −50.8 (7) | O2G—C2G—C3G—C4G | −174.9 (5) |
O3G—C1F—C2F—C3F | 71.9 (7) | C1G—C2G—C3G—C4G | −51.0 (7) |
O2F—C2F—C3F—O3F | −60.3 (8) | O3G—C3G—C4G—O4G | 53.0 (7) |
C1F—C2F—C3F—O3F | 173.3 (6) | C2G—C3G—C4G—O4G | −65.3 (7) |
O2F—C2F—C3F—C4F | 173.7 (5) | O3G—C3G—C4G—C5G | 172.8 (6) |
C1F—C2F—C3F—C4F | 47.3 (7) | C2G—C3G—C4G—C5G | 54.4 (7) |
O3F—C3F—C4F—O4F | −55.3 (7) | O4G—C4G—C5G—O5G | 65.6 (6) |
C2F—C3F—C4F—O4F | 71.8 (6) | C3G—C4G—C5G—O5G | −57.1 (7) |
O3F—C3F—C4F—C5F | −176.6 (6) | O4G—C4G—C5G—C6G | −53.3 (8) |
C2F—C3F—C4F—C5F | −49.5 (7) | C3G—C4G—C5G—C6G | −176.1 (6) |
O4F—C4F—C5F—O5F | −64.9 (7) | O5G—C5G—C6G—O6G | 69.9 (7) |
C3F—C4F—C5F—O5F | 53.6 (7) | C4G—C5G—C6G—O6G | −170.4 (6) |
O4F—C4F—C5F—C6F | 55.4 (8) | O5G—C1G—O1G—C7 | 67.5 (7) |
C3F—C4F—C5F—C6F | 173.9 (6) | C2G—C1G—O1G—C7 | −168.6 (5) |
O3G—C1F—O5F—C5F | −61.8 (6) | O5F—C1F—O3G—C3G | −65.4 (7) |
C2F—C1F—O5F—C5F | 57.6 (7) | C2F—C1F—O3G—C3G | 172.3 (5) |
C6F—C5F—O5F—C1F | 176.5 (5) | C4G—C3G—O3G—C1F | 97.7 (6) |
C4F—C5F—O5F—C1F | −59.0 (7) | C2G—C3G—O3G—C1F | −142.5 (5) |
O5G—C1G—C2G—O2G | 177.9 (5) | O1G—C1G—O5G—C5G | 62.6 (7) |
O1G—C1G—C2G—O2G | 53.1 (7) | C2G—C1G—O5G—C5G | −58.2 (7) |
O5G—C1G—C2G—C3G | 53.6 (7) | C6G—C5G—O5G—C1G | −179.8 (5) |
O1G—C1G—C2G—C3G | −71.1 (6) | C4G—C5G—O5G—C1G | 59.4 (7) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3f—H3f1···O6gi | 0.84 | 1.93 | 2.772 (7) | 177 |
O4f—H4f1···O3fii | 0.84 | 2.04 | 2.880 (7) | 175 |
O2g—H2g1···O2giii | 0.84 | 1.92 | 2.680 (7) | 149 |
O4g—H4g1···O5fiv | 0.84 | 2.08 | 2.827 (6) | 149 |
O6g—H6g···O3fv | 0.84 | 2.02 | 2.822 (7) | 158 |
Symmetry codes: (i) −x+1/2, −y+1, z−1/2; (ii) x−1/2, −y+1/2, −z+1; (iii) x+1/2, −y+3/2, −z+1; (iv) x+1, y, z; (v) −x+3/2, −y+1, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C13H24O10 |
Mr | 340.32 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 100 |
a, b, c (Å) | 4.78478 (11), 15.7859 (5), 19.4401 (5) |
V (Å3) | 1468.36 (7) |
Z | 4 |
Radiation type | Synchrotron, λ = 0.907 Å |
µ (mm−1) | 0.13 |
Crystal size (mm) | 0.03 × 0.01 × 0.01 |
Data collection | |
Diffractometer | Marresearch MARCCD 165 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7469, 1162, 975 |
Rint | 0.117 |
θmax (°) | 30.1 |
(sin θ/λ)max (Å−1) | 0.553 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.060, 0.177, 1.09 |
No. of reflections | 1162 |
No. of parameters | 216 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.30, −0.27 |
Computer programs: MARCCD (Marresearch, 2010), CrysAlis RED (Oxford Diffraction, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999), PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O3f—H3f1···O6gi | 0.84 | 1.93 | 2.772 (7) | 177 |
O4f—H4f1···O3fii | 0.84 | 2.04 | 2.880 (7) | 175 |
O2g—H2g1···O2giii | 0.84 | 1.92 | 2.680 (7) | 149 |
O4g—H4g1···O5fiv | 0.84 | 2.08 | 2.827 (6) | 149 |
O6g—H6g···O3fv | 0.84 | 2.02 | 2.822 (7) | 158 |
Symmetry codes: (i) −x+1/2, −y+1, z−1/2; (ii) x−1/2, −y+1/2, −z+1; (iii) x+1/2, −y+3/2, −z+1; (iv) x+1, y, z; (v) −x+3/2, −y+1, z+1/2. |
Acknowledgements
This work was supported by a grant from the Swedish Research Council and by the Faculty of Natural Sciences at Stockholm University
References
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Analysis of carbohydrate structure forms the basis of further studies related to interaction with other molecules and their function in different environments. Presently, the structural studies are often divided into the determination of the primary structure, i.e., sugar residues and substituents including their absolute configuration, ring form, anomeric configuration and sequential arrangement of the constituent components. Subsequently, in the second part the three-dimensional structure is determined, often by NMR spectroscopy but also with X-ray diffraction (XRD) techniques when crystals of suitable quality and sufficient size are available.
Polysaccharides are often built of repeating units of oligosaccharides having two to seven sugar residues in their repeats. To understand the physicochemical properties and immunological specificity of the polymers it is essential to obtain information on their structures, both the primary and the three-dimensional structures.
The capsular polysaccharide (CPS) of Klebsiella K63 contains a repeating unit consisting of → 3)-α-D-GalpA– (1 → 3)-α-L-Fucp-(1 → 3)-α-D-Galp-(1 → (Joseleau et al., 1979). More recently the CPS S-156 from Klebsiella pneumoniae ATCC 316 46 (Johansson et al., 1994) and the CPS from Klebsiella pneumoniae I-1507 (Guetta et al., 2003) were investigated. Their backbone structures were identical to that of the CPS from Klebsiella K63, i.e., trisaccharide repeating units, except for stoichiometric O-acetylation at O4 of the galacturonic acid.
The physicochemical effects of O-deacetylation were investigated for 'Fucogel', i.e., the CPS from strain I-1507 and revealed that the presence of the O-acetyl groups decreases the local stiffness of the polymer and lowers the rigidity of the polysaccharide as well as shortens the persistence length. The structural element α-L-Fucp-(1→3)-α-D-Galp makes up two thirds of the repeating unit in these polysaccharides and the title compound is the methyl glycoside thereof.
The torsion angles ϕH, ψH, and ω describe the major degrees of freedom in an oligosaccharide and for the title compound (I) the two former are present at the glycosidic α-(1 → 3)-linkage. In addition, for the galactose residue the ϕH torsion angle is also of interest. The ω torsion angle refers to the conformation of the hydroxymethyl group in the galactose residue. Both of the ϕH torsion angles in the structure are described by the exo-anomeric conformation with ϕH = 55 (1)° for the fucose residue and ϕH = -53 (1)° for the galactose residue (Fig. 1). The ψH torsion angle may in solution populate more that one conformational state (see below); for title compound (I) ψH = -24 (1)°. The conformation of the hydroxymethyl group is described by one of the three rotamers, gauche-trans, gauche-gauche, or trans-gauche with respect to the conformation of C6–O6 to C5–O5 and to C5–C4, respectively. In the present case the galactose residue has the gt conformation with ω = 70 (1)°, shifted away slightly from an ideal gauche conformation.
The Cremer-Pople parameters for the title compound are Q=0.525 (7) Å, θ=176.4 (8)° and ϕ=142 (10)° for the ring O5f → C5f and Q=0.556 (7) Å, θ=1.8 (7)° and ϕ=288 (14)° for the ring O5g → C5g; thus the conformation of both rings can be described as C-forms.
In the study of Fucogel the conformational space of the constituent disaccharides were investigated by molecular mechanics and Ramachandran maps. Two low energy regions were identified from the adiabatic map of α-L-Fucp-(1→ 3)-α-D-Galp with essentially equal potential energy at their minima being (i) ϕO5 = 279.6° and ψC4 = 140.4° and (ii) ϕO5 = 260.2° and ψC4 = 70.2°, in which the former torsion angle is defined by O5f—C1f—O3g—C3g and the latter by C1g—O3g—C3g—C4g. Interresidue hydrogen bonding was not present for these two conformations although it was identified for a significantly higher-energy conformation.
The conformation of the title compound I and the corresponding glycosidic torsion angles in the polysaccharide are indeed quite similar. The resemblance of the crystal structure and the two low-energy minima of the adiabatic map suggests that torsion angle information from XRD data may be suitable as starting points for molecular modeling of oligo- and polysaccharides.
Interestingly, a fiber X-ray diffraction study of the Klebsiella K63 CPS shows that it forms an extended 2-fold helix (Elloway et al., 1980).