Dr. John James Rickard Macleod, Scottish biochemist and physiologist, was born in Clunie in central Scotland in 1876. He studied medicine at the University of Aberdeen. He obtained a Ph.D. in 1898 and then studied biochemistry at the University of Leipzig in Germany for 1 year. After worldwar I, he moved to the University of Toronto and became the director of the physiology lab.

Dr. Frederick Grant Banting was born near Alliston, Ontario in 1891. He studied medicine at the University of Toronto and served as a doctor in the army in world war I. He obtained his MD in 1922.

In 1920, while preparing for a lecture on pancreas Frederick Grant Banting came across the work of scientists who had reported on the existence of a hormone named insulin, the absence of which led to increased blood sugar and diabetes. At that time biochemists were struggling to isolate this hormone from the pancreas because the hormone was degraded very quickly by trypsin, which is also produced in the pancreas. Banting came across the work of Moses Barron who had reported about a method to destroy the trypsin producing cells of the pancreas. He discussed the possibility of isolating insulin from the pancreas, with John Macleod who provided the experimental facilities and assistance of his student Dr. Charles Best. Banting and Best, with the assistance of a biochemist James Collip, isolated insulin from dog pancreas by first destroying trypsin producing cells and then crushing the pancreas.

John Macleod and Fredrick Banting received the Nobel prize in physiology or medicine for this work in 1923. Banting remains the youngest Nobel laureate in physiology or medicine. He shared half his Nobel prize money with Charles Best while Macleod shared half of his with James Collin. King George V. knighted banting for his work.

Until the production of insulin by genetically engineered bacteria in the late 20th century, the method developed by Banting and Best served as the primary technique of commercial insulin production.

References:

Frederick G. Banting - Biographical". Nobelprize.org. Nobel Media AB 2014. http://www.nobelprize.org/nobel_prizes/medicine/laureates/1923/banting-bio.html

John Macleod - Biographical". Nobelprize.org. Nobel Media AB 2014. http://www.nobelprize.org/nobel_prizes/medicine/laureates/1923/macleod-bio.html