Is it a standard practice to name functional group by the greek alphabet of the carbon it is attached to?

Recently read a question in which the order of translation (protein synthesis) was asked and there were a couple of options with the $\ce{NH2}$ was labelled as $\ce{\alpha-NH2}$ and $\ce{COOH}$ as $\ce{\alpha-COOH}$.

I read wiki, it says H atoms are labeled in that way but are functional groups too labeled in the same way?

  • $\begingroup$ As you can see, they are. $\endgroup$
    – Mithoron
    Apr 29, 2017 at 15:50
  • 1
    $\begingroup$ Definitely not standard though. Standard is nothing but the IUPAC name. These are simply useful notations chemists use in certain chemicals as they have useful properties being that way. $\endgroup$ Apr 29, 2017 at 16:39

1 Answer 1


In the study of amino acids (and peptides, proteins etc), it IS standard practice to label the alpha carbon as such. More carbons leading into the R-group may also be labeled with Greek letters, but this is not as necessary as having a label for the stereogenic center, the alpha carbon. Personally, I've found Greek letters helpful in remembering the structures of the different amino acids, for example I always think of Lysine as "the one with the epsilon-amino side chain". Note that in chemistry in general, whose nomenclature follows IUPAC guidelines, it is NOT "standard" to use Greek lettering, however it is still generally recognized. The practice is probably most prominent in the study of fatty acids (another biochemistry subfield), which results in such Greek -rich categorizations as "omega-3 unsaturated fats".


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