Efraim Racker (June 28, 1913 – September 9, 1991) was an Austrian biochemist who was responsible for identifying and purifying Factor 1 (F1), the first part of the ATP synthase enzyme to be characterised.

Maynard E. Pullam joined Racker's staff in 1953, and decided to uncover the mechanism of ATP synthesis in mitochondria and chloroplasts.

[3] Efraim Racker died in 1991, but not before coining the phrase, "Don't waste clean thinking on dirty enzymes," which is often quoted as one of "The Ten Commandments of Enzymology".

[2] Racker and his associates, Anima Datta, Maynard Pullmand, and Harvey Penefsky, worked to isolate the enzymes involved in ATP synthesis.

This discovery had the added benefit of silencing any critics of the role of F1 in oxidative phosphorylation because it conferred oligomycin sensitivity on the ATPase activity complex.

[4] Once both of these factors were identified Racker was able to confirm Peter D. Mitchell's hypothesis that contrary to popular opinion, ATP synthesis was not coupled to respiration through a high-energy intermediate but instead by a transmembrane proton gradient.