The Chemical Entities of Biological Interest (ChEBI) ontology is downloaded weekly from EMBL-EBI at http://www.ebi.ac.uk/chebi/. The data is made available under the Creative Commons License (CC BY 3.0, http://creativecommons.org/licenses/by/3.0/). For more information see: Degtyarenko et al. (2008) ChEBI: a database and ontology for chemical entities of biological interest. Nucleic Acids Res. 36, D344–D350.
A deuterated compound that is is an isotopologue of 3-(trimethylsilyl)propane-1-sulfonic acid (DSS) in which the six hydrogen atoms attached to the carbon chain linking the silicon and the sulfur atoms have been replaced by deuterium. It is often used in NMR spectroscopy (often as the corresponding sodium salt) as a calibration standard - it is much more water soluble that tetramethylsilane, so is often used for studies on proteins in water.