2,2-dimethyl-2-silapentane-5-sulfonic acid

TMS cannot be used as an internal reference for substances dissolved in DjO. For aqueous solutions, the standard used is often the sodium salt of 2,2-dimethyl-2-silapentane-5-sulfonic acid or DSS. 

All proton NMR spectra were recorded on a Varian Unity 600 at 25 C. 6 to 10 mg of the disulfide linked c-Myc-Max heterodimeric LZ were dissolved in 0.5 mL of potassium phosphate buffer (50 mM, 10% DiO / 90% H2O and pH 4.7) containing 100 mM KCl and ImM 2,2-dimethyl-2-silapentane-5-sulfonic acid (DSS) to yield solutions ranging from 0.75 to 1.25 mM. Proton resonances were assigned from two-dimensional double quantum filtered correlation spectroscopy (DQF-COSY (21)), two-dimensional total correlation spectrocopy (TOCSY mixing time = 50 ms (22)) and two-dimensional nuclear Overhauser enhancement spectrocopy (NOESY mixing times = 150 and 200 ms (23)) experiments. Sequential assignment of the proton resonances was performed as described by Wuthrich (24). 

The H nmr spectrum in D20 exhibits a single resonance at 2.52 ppm for the methyl protons with DSS, the sodium salt of 2,2-dimethyl-2-silapentane-5-sulfonic acid as reference. The electronic spectrum for an aqueous solution is characterized by an absorption maximum at 358 nm (e = 7.4 Lrnole 1 cm 1) in H20. Other physical properties are described in the literature [the checkers report 5(CH3) = 2.6 ppm with Xmax = 336 nm, e = 650 Lmol 1 cm"1 ]. 

For successful NMR experiments a protein solution of high purity (>95%), stability (over a week), and appropriate concentration (0.1-1 mM) is needed the total sample volume and mass should be 350-550 uL and 3-30 mg, respectively. 2,2-Dimethyl-2-silapentane-5-sulfonic acid (DSS) rather than tetramethylsUane (TMS) is used as a reference compound. Although both natural and synthetic polypeptides and proteins can be used, most samples are expressed via a suitable prokaryotic or eukaryotic cellular or ceU-free recombinant technique. The latter method eliminates most toxic effects attributed to the overproduction of recombinant proteins. Biotechnological approaches have the common advantage of large-scale protein production, specific or non-specific stable isotope labeling, and easy sequence variation. 

DSS is 3-(trimethylsilyl)-l-propane sulfonic acid, sodium salt (or sodium 2,2-dimethyl-2-silapentane-5-sulfonate). TSP is sodium -3-trimethylpropionate -2, 2, 3, 3-d. Both are reference standards used in aqueous solutions. 

H N.m.r. Chemical Shifts (p.p.m. from 4,4-Dimethyl-4-silapentane-l-sulfonate at 295 K) of the H-3 Axial and H-3 Equatorial Protons of Oligosaccharides Containing TV-Acetylneuraminic Acid and N-Glycolylneuraminic Acid... 

Trimethylsilyl)-l-propanesulfonic acid sodium salt (sodium 4,4-dimethyl-4-silapentane-1-sulfonate DSS)... 

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