chemotaxonomy

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The classification of organisms based on differences at the biochemical level, as in the amino acid sequences of common proteins.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biochemistry, genetics the classification or taxonomy of organisms based on differences and similarities in biochemistry, especially on differences in amino acid sequence in proteins that the organisms have in common