Written by: Victor Malone

John Macleod: The Biochemist Behind the Discovery of Insulin

John Macleod, a Scottish biochemist and physiologist, is renowned for his instrumental role in the discovery and isolation of insulin, a breakthrough that earned him the 1923 Nobel Prize in Physiology or Medicine, alongside Frederick Banting.

Early Life and Education

Born on September 6, 1876, in Clunie, near Dunkeld in Perthshire, Scotland, Macleod's family soon relocated to Aberdeen, where he attended Aberdeen Grammar School and subsequently enrolled in the study of medicine at the University of Aberdeen.

• At the University of Aberdeen, Macleod was influenced by one of his principal teachers, the young professor John Alexander MacWilliam.
• In 1898, he was awarded his medical degree with honors, which was followed by a year of studying biochemistry at the University of Leipzig, Germany, on a traveling scholarship.

Academic Career and Research

Macleod's academic career spanned across several prestigious institutions, including the London Hospital Medical School, where he was appointed lecturer in biochemistry in 1902, and the Western Reserve University in Cleveland, Ohio, where he served as a lecturer in physiology from 1903 to 1918.

• During his tenure at Western Reserve University, Macleod developed a keen interest in carbohydrate metabolism, a focus that would remain a significant aspect of his research throughout his career.
• In 1910, he delivered a lecture on various forms of experimental diabetes and their significance for diabetes mellitus at the joint meeting of the section on Pharmacology and Therapeutics and the section on Pathology and Physiology of the American Medical Association.

The Discovery of Insulin

In 1916, Macleod became a professor of physiology at McGill University in Montreal, Canada, where he collaborated with Frederick Banting and Charles Best to investigate the pancreatic extract that would eventually become insulin.

Together, they successfully isolated insulin, a discovery that revolutionized the treatment of diabetes and earned Macleod and Banting the 1923 Nobel Prize in Physiology or Medicine.

Legacy and Impact

Macleod's work on insulin not only transformed the medical landscape but also paved the way for further research into the treatment of diabetes.

• His contributions to the field of biochemistry and physiology have been recognized through various honors and awards, including the Royal Medal of the Royal Society in 1923.
• Macleod's legacy extends beyond his scientific achievements, as he played a pivotal role in shaping the careers of numerous students and researchers who went on to make significant contributions to their respective fields.

Personal Life and Later Years

Macleod's later years were marked by his return to Scotland, where he served as the regius professor of medicine at the University of Aberdeen from 1928 until his death on March 16, 1935.

Throughout his life, Macleod remained committed to his research and academic pursuits, leaving behind a lasting legacy in the fields of biochemistry and physiology.