The Massachusetts Institute of Technology, where he was an emeritus professor of biology and chemistry, said Khorana died of natural causes Nov. 9 in Concord, Mass.
He won the Nobel Prize in 1968 for work that helped decipher the genetic code and explain how cells make proteins, the Los Angeles Times reported.
Khorana shared the prize with two other scientists, Robert W. Holley of Cornell University and Marshall W. Nirenberg of the National Institutes of Health.
Working independently, they were recognized "for their interpretation of the genetic code and its function in protein synthesis," the Nobel citation said, in a breakthrough that would pave the way for genetic engineering.
Khorana was born in 1922 in the tiny Punjabi village of Raipur, now part of Pakistan.
Although the family was poor, his father emphasized education and Khorana earned a scholarship to Punjab University in Lahore, earning a bachelor's degree in 1943, and a master's in 1945 in chemistry and biochemistry.
He left India in 1945 to study at Liverpool University, where he received his doctorate in organic chemistry in 1948 and later held research positions in Cambridge, England, and in Vancouver, Canada.
Khorana moved to the University of Wisconsin at Madison in 1960 and became a naturalized American citizen in 1966.
He left Wisconsin for MIT in 1970 and retired in 2007.