Hara Gobind Khorana American biochemist (of Indian descent) Date of Birth: 09.01.1922 Country: USA

1. Early Life and Education
2. Research Career
3. Deciphering the Genetic Code
4. Nobel Prize and Later Achievements
5. Personal Life and Recognition

Early Life and Education

Har Gobind Khorana was born on January 9, 1922, in the small village of Raipur, Punjab (present-day Pakistan). His parents, Ganpat Rai Khorana and Krishna Khorana (Devi), were Indian subjects and members of the Sikh community. Despite their humble beginnings, the Khorana family valued education, and young Har Gobind received his early instruction from a village teacher.

He completed his secondary education at Multan High School in Punjab and then pursued a degree in chemistry at Punjab University in Lahore. Graduating with a Bachelor of Science (Honours) in 1943 and a Master of Science (Honours) two years later, Khorana's academic excellence earned him a government scholarship to study organic chemistry at the University of Liverpool.

In 1948, he received his PhD in organic chemistry for his dissertation on violacein, a chemical pigment that colors certain bacterial cells. Subsequently, he spent a year at the Swiss Federal Institute of Technology in Zurich, studying the chemical structure of alkaloids with Vladimir Prelog.

Research Career

In 1949, Khorana was appointed a research fellow at the University of Cambridge. Working alongside Alexander Todd, he developed an interest in the biochemistry of nucleic acids, complex molecules found in cell nuclei. In 1952, he became Director of the Division of Organic Chemistry at the British Columbia Research Council in Vancouver, Canada.

There, he investigated the chemical structure of acetyl coenzyme A (CoA). Enzymes are proteins that accelerate biochemical reactions, while coenzymes are essential to enzyme function. Acetyl-CoA, discovered by Fritz Lipmann in 1945, is a key player in carbohydrate, lipid, and protein metabolism. In 1949, Khorana and his colleague John Moffatt synthesized acetyl-CoA, a breakthrough that significantly lowered the cost and complexity of acquiring the substance.

In 1960, Khorana was recruited as Head of the Institute for Enzyme Research at the University of Wisconsin-Madison. The following year, he published "Some Recent Developments in the Chemistry of Phosphate Esters of Biological Interest." In 1963, he was appointed an editor of the Journal of the American Chemical Society, and in 1964, he became a Professor of Biological Sciences at the University of Wisconsin.

Deciphering the Genetic Code

Khorana's research interests shifted towards the complex problems of modern genetics, including the biochemistry of nucleic acids, the biosynthesis of cellular proteins (enzymes), and the nature of genes. In 1953, Francis Crick and James D. Watson elucidated the three-dimensional structure of DNA. Resembling a twisted ladder, DNA is composed of two chains of nucleotides, each consisting of a sugar molecule (deoxyribose), a nitrogenous base, and a phosphate group.

The sequence of these four bases within DNA determines the genetic code. Triplet combinations of bases instruct cells on which amino acid to incorporate into protein molecules. One gene contains the instructions for synthesizing a single protein molecule, and RNA molecules carry that genetic code to ribosomes, the organelles responsible for protein synthesis.

Nobel Prize and Later Achievements

In the early 1960s, Khorana embarked on a quest to decipher the genetic code. He devised a series of experiments utilizing Marshall W. Nirenberg's protein synthesis system and identified the base sequences for all 20 amino acids. His work revealed that some amino acids were encoded by multiple triplets, indicating imperfections in the genetic code.

Khorana and his colleagues synthesized DNA and RNA chains containing all 64 possible triplets and identified those that signaled the start and stop of specific protein synthesis. They also elucidated the secondary chemical structure of transfer RNA (tRNA), which carries amino acids to ribosomes. In 1968, Khorana, Robert W. Holley, and Nirenberg received the Nobel Prize in Physiology or Medicine "for their interpretation of the genetic code and its function in protein synthesis."

Following his Nobel recognition, Khorana and his team achieved the first synthesis of a gene (the yeast alanine transfer RNA gene) in 1970. In 1971, he accepted a position as Professor of Biology and Chemistry at the Massachusetts Institute of Technology.

Personal Life and Recognition

Khorana married Esther Elizabeth Sibler in 1952, and together they raised a son and two daughters. He naturalized as an American citizen in 1966. Known for his exceptional work ethic, Khorana once spent 12 years without taking a vacation. He enjoyed listening to music and taking walks during which he jotted down scientific ideas.

Throughout his career, Khorana received numerous awards, including the Merck Award of the Canadian Institute of Chemistry (1958), the Louisa Gross Horwitz Prize from Columbia University (1968), the Albert Lasker Award for Basic Medical Research (1968), and the Willard Gibbs Medal from the American Chemical Society (1974). He was a member of the National Academy of Sciences, the American Association for the Advancement of Science, the American Chemical Society, and the American Society for Biochemistry and Molecular Biology.