John Jacob Abel the position of chair of the department until he retired at the age of 75 in 1932. Ever since his early years in Europe, Abel showed great interest in isolating pure form of internal gland hormones. The first work that led to his international reputation as a pharmacologist and biochemist was the isolation of epinephrine from adrenal medulla. However, he was only able to isolate a monobenzoyl derivative of epinephrine. While he was improving his processes on decomposing the benzoyl derivative to obtain salts of epinephrine using saponification, a Japanese chemist J. Takamine, who had visited his lab, was able
John Jacob Abel some preliminary experiments on the subject, Abel decided to take on the research, and replied to his friend, "Will attack insulin. Writing. J. J. Abel." Abel invested the next few years on purifying insulin. While he was trying various means to purify insulin, he had the idea to measure sulfur content of his extracts and found that the higher the sulfur content, the greater the activity. The discovery not only significantly precipitated progress on extracting active fractions but also offered the very first concrete information on the structure of insulin—sulfur is an integral part of insulin molecules. Continuing with his