In one experiment, this chemical's incorporation into a protein's amide groups is used as a measure of the solvent accessibility of the residues. The rate-limiting step of an enzyme can be slowed down by the incorporation of 
In one experiment, this chemical's incorporation into a protein's amide groups is used as a measure of the solvent accessibility of the residues. The rate-limiting step of an enzyme can be slowed down by the incorporation of this chemical, a process known as the primary isotope effect. Almost all of this chemical was produced during the Big Bang nucleosynthesis and is also produced in the first step of the proton-proton chain. The incorporation of this chemical into acidic positions of a molecule can be monitored by NMR, and solvents for that technique usually contain this chemical since it doesn't show up on proton NMR. Also found in heavy water, for 10 points, name this isotope of hydrogen with atomic mass two.
In one experiment, this chemical's incorporation into a protein's amide groups is used as a measure of the solvent accessibility of the residues.
{Deuterium} or {H}-{2}