Researchers are exploring whether these ubiquitous fluorinated molecules might worsen infections or hamper vaccine effectiveness.
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Edited by George N. Somero, Stanford University, Pacific Grove, CA, and approved October 13, 2009 (received for review September 1, 2009)
Article Figures & SI
Figures
- Fig. 1.
SDS/PAGE (12%) of R1 and R2 fractions. (A) Silver-stained gel. Lane assignments: 1, ice-purified R1; 2, low-molecular-weight standards. (B) Silver stained gel. Lane assignments: 1, low-molecular-weight standards; 2, ice purified R2. (C) Gel stained with Sypro Ruby. Lane assignments: 1, low molecular weight standards; 2, blank (loading dye only); 3, ice purified R1; 4, ice purified R2. Ice-purified R1 and R2 were applied to two additional lanes (lanes 5 and 6, respectively), which were excised from the gel. Each lane was divided into four segments and the THF was eluted in distilled water overnight. After dialysis, the sample was concentrated and TH was measured. TH values (°C) are shown for lanes 5 and 6 for each gel fragment.
- Fig. 2.
UV absorbance spectra of R1 and R2 fractions compared with that of BSA. Squares, BSA at 0.12 mg/ml; circles, 1:100 dilution of R2; triangles, 1:100 dilution of R1.
- Fig. 3.
A comparison of 600 MHz 1H NMR spectra of THFs isolated by ice affinity from three successive extraction buffers. (A) Buffer R1, soluble fraction. (B) Buffer R2, first membrane-associated fraction. (C) Buffer R3, second membrane-associated fraction. Decreasing signal to noise indicates lower THF concentrations.
- Fig. 4.
Partial 800 MHz 1H NMR and TOCSY spectra of R1 showing correlations among lipid signals. (A) 1H NMR spectrum showing lipid signals that correspond to crosspeaks in (B). Numbers below the bracketed regions indicate relative signal areas. (B) Cross-peaks (connected by dashed lines) in the TOCSY spectrum indicate spin connectivities between CH3 and different types of -CH2-protons in the fatty acid constituent of the R1 THF.
- Fig. 5.
MALDI-TOF mass spectrum of R1. Red and blue brackets indicate ions separated by either the mass of an aldohexose (180.06–18.01 [reducing end H2O] = 162.05 Da) or aldopentose (150.05–18.01 [reducing end H2O] = 132.04 Da), respectively.
- Fig. 6.
Partial 2D 1H NMR spectra of R1 at 800 MHz. (A) Partial HSQC spectrum showing 1H-13C correlations for the saccharide 1H signals shown in (B). Black contours correlate 13C and methylene (-CH2-) protons, and red contours correlate 13C to methine (-CH =) or methyl (-CH3) protons. Crosspeak assignments for the Manp and Xylp constituents are shown as M1-M6′ and X1-X5′, respectively. (B) Partial 1D 1H NMR spectrum showing saccharide signals observed for R1. (C) Expansion of the anomeric signals observed in the HSQC spectrum. (D) Partial HSQC-TOCSY spectrum showing proton signals in (B) that correlate with the anomeric signals observed in (C), allowing identification of most of the ring protons in Xylp, but only H2 in Manp because of the small 3JH1,H2 and 3JH2,H3 values in Man residues.
- Fig. 7.
Proposed disaccharide core structure comprising the THF isolated from U. ceramboides.
Tables
- Table 1.
13C and 1H chemical shifts (ppm) and 1H–1H spin-couplings for lipid signals in R1 compared with those observed for a glycolipid isolated from Deinococcus radiodurans
Chemical shifts (ppm) J-coupling (Hz) CH2CO CH2CH2CO -CH2-n -CH3 Fatty acid-R1 3JH2,H3 δ 13C — — 28.6 — 7.5 ± 0.1 δ 1H 2.33 1.71 1.43–1.52 1.04 Multiplicity triplet multiplet multiplet multiplet Fatty acid† 3JH2,H3 δ 13C — — ≈29 — 7.4 δ 1H 2.33 1.62 1.1–1.4 0.87–0.92 Multiplicity triplet multiplet multiplet Triplet × 3 *In 2H2O at 40 °C, pH 7.5; accurate to ± 0.01 ppm. Chemical shifts were referenced to the internal HOD signal (4.800 ppm).
↵†Data taken from ref. 25.
- Table 2.
13C and 1H chemical shifts (ppm) and 1H–1H and 13C–1H spin-couplings for saccharide signals in R1 and standard compounds
Chemical shifts (ppm) J-coupling (Hz) C1(H1) C2(H2) C3(H3) C4(H4) C5(H5,H5′) C6(H6,H6′) Man: R1 100.2 (4.92) 70.1 (4.30) 71.6 (3.98) 76.6† (3.96) 75.1 (3.74) 60.6 (4.09, 3.93) 1JC1,H1 ≈160 Methyl α-d-manno-pyranoside‡,§ 101.9 (4.854) 71.2 (4.024) 71.8 (3.851) 68.0 (3.739) 73.7 (3.70) 62.1 (3.991, 3.852) 1JC1,H1171.0 Methyl β-d-manno-pyranoside‡,§ 101.3 (4.658) 70.6 (4.072) 73.3 (3.721) 67.1 (3.625) 76.6 (3.459) 61.4 (4.021, 3.825) 1JC1,H1159.5 Xyl: R1 101.7 (4.66) 72.8 (3.48) 73.8 (3.73) 76.6† (4.00) 63.0 (4.28, 3.55) 3JH1,H27.8 Methyl α-d-xylopyranoside‡,§ 100.6 (4.868) 72.3 74.3 70.4 62.0 3JH1,H2 3.6 Methyl β-d-xylopyranoside‡,§ 105.1 (4.415) 74.0 (3.345) 76.9 (3.533) 70.4 (3.713) 66.3 (4.064, 3.419) 3JH1,H2 7.8 *In 2H2O at 40 °C, pH 7.5; accurate to ±0.01 ppm. Chemical shifts were referenced to the internal HOD signal (4,800 ppm).
↵†Carbon resonances shifted 7–10 ppm downfield when compared with analogous carbons in the corresponding unsubstituted methyl glycoside, indicating involvement in an O-glycosidic linkage.
↵‡Data taken from ref. 35.
↵§Data taken from ref. 27.
A nonprotein thermal hysteresis-producing xylomannan antifreeze in the freeze-tolerant Alaskan beetle Upis ceramboides
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- Biological Sciences
- Biochemistry
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