Phoebus Aaron Theodore Levene (25 February 1869 – 6 September 1940) was a Russian-born American biochemist who studied the structure and function of nucleic acids.

[1] He was born into a Litvak (Lithuanian Jewish) family as Fishel Rostropovich Levin in the town of Žagarė in Lithuania, then part of the Russian Empire, but grew up in St. Petersburg.

Levene enrolled at Columbia University and in his spare time conducted biochemical research, publishing papers on the chemical structure of sugars.

Levene is known for his tetranucleotide hypothesis[7] which proposed that DNA was made up of equal amounts of adenine, guanine, cytosine, and thymine.

Before the later work of Erwin Chargaff, it was widely thought that DNA was organized into repeating tetranucleotides in a way that could not carry genetic information.