Chemical shift ratios for indirect referencing of 13C, 15N, and 31P chemical shifts. Chemical shift ratios are kindly solicited for other X-1H pairs. Please submit them along with a short description of their derivation to [email protected].

Nuclei	        Chemical Shift    Sample    Literature Reference
                     Ratio

1H     (DSS)    1.000000000       a         1, 2
2H     (DSS)    0.153506088       a         2, 5 
13C-1H (DSS)    0.251449530       a         1, 2
15N-1H (DSS)    0.101329118       b         1, 2
31P-1H (DSS)    0.404808636       h         2, 6

Nuclei          Chemical Shift    Temp. Factor                 Literature 
                     Ratio                                     Reference

13C-1H (DSS)	0.251449519       (T - 300 K) x 1.04 x 10-9    1

15N-1H (1H DSS)	0.101329112       (T - 300 K) x 2.74 x 10-10   1

Nuclei          Chemical Shift    Sample    Literature Reference
                     Ratio

13C-1H (DSS)	0.251449528       a         1
13C-1H (DSS)	0.251449537       a         1
13C-1H (DSS)	0.251449519       d         1
13C-1H (DSS)	0.251449531       e         1
13C-1H (TSP)	0.25144954        f         3

15N-1H (1H DSS)	0.101329118       b         1
15N-1H (1H DSS)	0.101329002       e         1
15N-1H (1H DSS)	0.101329112       d         1
15N-1H (1H TMS)	0.1013291444      g         4    (Derived for liquid ammonia)
15N-1H (1H TMS)	0.10136767        n         4    (CH3NO2/TMS ratio) 

19F-1H (DSS)    0.940867196       i         7    (TFA in a capillary)
19F-1H (DSS)    0.940866982       i         7    (TFA in a sphere)
19F-1H (DSS)    0.940865707       j         7    (TFE in a capillary)
19F-1H (DSS)    0.940865527       j         7    (TFE in a sphere)

31P-1H (DSS)    0.404807210       k         7    (H3PO4 in a capillary)
31P-1H (DSS)    0.404807356       k         7    (H3PO4 in a sphere)
31P-1H (DSS)    0.404806249       m         7    (PCr in a capillary)
31P-1H (DSS)    0.404806249       m         7    (PCr in a sphere)

  Sample Designation        Sample Contents and Conditions

         a                  10 mM DSS in 99.8 % D2O,  25 C
         b                  10 mM DSS in 99.8% D2O with anhydrous liquid
                                 ammonia in an external capillary, 25 C
         d                  DSS in 1 M NH4NO3, 1 M HNO3, 25 C
         e                  5 mM DSS in liquid ammonia, 25 C
         f                  TSP in D2O, 22 C
         g                  Derived for liquid ammonia from a sample of TMS in CH3NO2
         h                  10% trimethylphosphate; 2 mM DSS in 99.8% D2O, 25 C
         i                  10 mM DSS in D2O pH 7.0, outer volume; 
                                 100% trifluoroacetic acid (capillary or
                                 sphere): 25 C
         j                  10 mM DSS in D2O pH 7.0, outer volume;
                                 100% trifluorethanol (capillary or sphere): 25 C
         k                  10 mM DSS in D2O pH 7.0, outer volume;
                                 85% ortho-phosphoric acid in H2O 
                                 (capillary or sphere): 25 C
         m                  10 mM DSS in D2O pH 7.0, outer volume:
                                 10 mM phosphocreatine in H2O
                                 (capillary or sphere): 25 C
         n                  TMS in CH3NO2

1. Wishart, D. S., Bigam, C. G., Yao, J., Abildgaard, F., Dyson, H. J., Oldfield, E., Markley, J. L., and Sykes, B. D., "1H, 13C and 15N Chemical Shift Referencing in Biomolecular NMR," J. Biomol. NMR 6, 135-140 (1995).

2. Markley, J. L., Bax, A., Arata, Y., Hilbers, C. W., Kaptein, R., Sykes, B. D., Wright, P. E., and Wüthrich, K., "Recommendations for the Presentation of NMR Structures of Proteins and Nucleic Acids,". Pure & Appl. Chem. 70, 117-142 (1998).

3. Bax, A. and Subramanian, J., "Sensitivity-Enhanced Two-Dimensional Heteronuclear Shift Correlation NMR Spectroscopy," J. Magn. Reson. 67, 565-570 (1986).

4. Live, D. H., Davis, D. G., Agosta, W. C., and Cowburn, D., "Long Range Hydrogen Bond Mediated Effects in Peptides: 15N NMR Study of Gramicidin S in Water and Organic Solvents," J. Am. Chem. Soc. 106, 1939-1943 (1984).

5. The chi value recommended here for 2H was determined from the ratios of 1H and 2H signals of a water sample at 298 K as measured by Dr. Frits Abildgaard and David LeMaster at the National Magnetic Resonance Facility at Madison. This value is a surrogate for the isotopomers of DSS, and its derivation assumes that there is no primary isotope effect on the ratio.

6. The chi value recommended here for 31P is the average of values determined independently, one at the National Magnetic Resonance Facility at Madison by F. Abildgaard (40.4808651), and the other at the National Institutes of Health by A. Bax (40.480862). Measurements were made at 298 K in D2O solution containing 10% trimethylphosphate as the indirect reference and DSS as the direct reference.

7. Maurer, T. and Kalbitzer, H. R., "Indirect Referencing of 31P and 19F NMR Spectra," J. Magn. Reson. B 113, 177-178 (1996).