Coenzyme A
Working mostly separately, Lynen and Bloch both discovered the steps that created squalene and turned the squalene into cholesterol. Initially, Lynen found that acetate activated by Coenzyme A was needed to start the process. He discovered the chemical structure of acetyl-coenzyme A, which was needed for a detailed understanding of the biochemical pathways. He also learned that biotin, or Vitamin B7, was needed for in the process.