2. Har Gobind Khorana
(9 January 1922 – 9 November 2011)was an Indian American
biochemist. While on the faculty of the University of
Wisconsin–Madison, he shared the 1968 Nobel Prize for
Physiology or Medicine with Marshall W. Nirenberg and
Robert W. Holley for research that showed the order of
nucleotides in nucleic acids, which carry the genetic code of
the cell and control the cell's synthesis of proteins. Khorana
and Nirenberg were also awarded the Louisa Gross Horwitz
Prize from Columbia University in the same year. Born in
British India, Khorana served on the faculties of three
universities in North America. He became a naturalized
citizen of the United States in 1966, and received the
National Medal of Science in 1987.
3. Research
• Ribonucleic acid (RNA) with two repeating units
(UCUCUCU → UCU CUC UCU) produced two alternating
amino acids. This, combined with the Nirenberg and
Leder experiment, showed that UCU genetically odes
for serine and CUC codes for leucine. 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 dipeptides
and tripeptides thus revealing that UAG, UAA, and UGA
are stop codons. Their Nobel lecture was delivered on
12 December 1968. Khorana was the first scientist to
chemically synthesize oligonucleotides. [26] This
achievement, in the 1970s, was also the world's first
synthetic gene; in later years, the process has become
widespread . Subsequent scientists referred to his
research while advancing genome editing with the
CRISPR/Cas9 system.
4. Subsequent Research
• He extended the above to long DNA polymers using non-aqueous
chemistry and assembled these into the first synthetic gene, using
polymerase and ligase enzymes that link pieces of DNA together, as well
as methods that anticipated the invention of polymerase chain reaction
(PCR). These custom-designed pieces of artificial genes are widely used
in biology labs for sequencing, cloning and engineering new plants and
animals, and are integral to the expanding use of DNA analysis to
understand gene-based human disease as well as human evolution.
Khorana's invention(s) have become automated and commercialized so
that anyone now can order a synthetic oligonucleotide or a gene from
any of a number of companies. One merely needs to send the genetic
sequence to one of the companies to receive an oligonucleotide with the
desired sequence. After the middle of the 1970s, his lab studied the
biochemistry of bacteriorhodopsin, a membrane protein that converts
light energy into chemical energy by creating a proton gradient. Later, his
lab went on to study the structurally related visual pigment known as
rhodopsin. A summary of his work was provided by a former colleague at
the University of Wisconsin: "Khorana was an early practitioner, and
perhaps a founding father, of the field of chemical biology. He brought
the power of chemical synthesis to bear on deciphering the genetic code,
relying on different combinations of trinucleotides.
5. Awards And Honors
NIH lecture award
Padma Vibhushan Nobel Prize in Physiology
or Medicine
Louisa Gross Horwitz Prize
Albert Lasker Award for Basic Medical Research
National Medal of Science for
Biological Sciences
Canada Gairdner
International Award
