Har Gobind Khorana (born January 9, 1922) is a U.S. molecular biologist.

Khorana was born in Raipur (at that time India, now Pakistan). In 1945, he began studies at the University of Liverpool. After earning a Ph. D., he spend a postdoc year in Zürich (1948-49). He then returned to England and worked at Cambridge until 1952. He married Esther Elizabeth Sibler the same year. After that, he worked at universities in Vancouver and Wisconsin.

Khorana was awarded the 1968 Nobel Prize in Medicine (together with Robert W. Holley and Marshall W. Nirenberg) for describing the genetic code and how it operates in protein synthesis.

Khorana's synthetic RNA approach

RNAs with two repeating units (UCUCUCU --> UCU CUC UCU) produced two alternating amino acids. This combined with the Nirenberg and Leder experiment showed that UCU codes for Ser and CUC for Leu.

RNAs with three repeating units (UACUACUA --> UAC UAC UAC, or ACU ACU ACU, or CUA, CUA, CUA) produced three different strings of amino acids.

RNAs with four repeating units including UAG, UAA, or UGA, produced only dipiptides and tripeptides thus revealing that UAG, UAA and UGA are stop codons.