Amino acid dating
This site stores nothing other than an automatically generated session ID in the cookie; no other information is captured.In general, only the information that you provide, or the choices you make while visiting a web site, can be stored in a cookie.The amino acids combine with each other like the links of a chain to form a long protein chain.Proteins contain from 50 to several hundred amino acids.The racemization of L-isoleucine to D-alloisoleucine is, therefore, of special interest in the amino acid racemization dating system.
Jeffrey Bada of Scripps Institute of Oceanography announced the "discovery" of a new dating method based on the rate of racemization of amino acids in fossil material.
L-Isoleucine racemizes (technically in this case, since there are two asymmetric carbon atoms, the correct term is epimerization rather than racemization) almost exclusively to one form, called D-alloisoleucine.
Ordinarily it is difficult to separate an L-amino acid from its D-form, but L-isoleucine is easily separated from D-alloisoleucine.
The two forms are known as L-amino acids and D-amino acids, the L and D designating the direction in which solutions of these amino acids rotate plane-polarized light.
They are mirror-images of each other, and one cannot be superimposed on the other, just as is true of left and right hands.Each amino acid has two chemical groups, an amino group and a carboxyl group, which can form chemical bonds with other amino acids.