Aziz Sancar: From a Small Town in Turkey to the Nobel Prize in Chemistry

Aziz Sancar (born 8 September 1946) is a Turkish-American biochemist and molecular biologist who revealed how living cells repair DNA damaged by ultraviolet light. In 2015 he shared the Nobel Prize in Chemistry with Tomas Lindahl and Paul Modrich. His legacy in one line: he showed, enzyme by enzyme, how a cell cuts out and replaces damaged DNA, turning a vague biological idea into precise chemistry.

Early Life and Family

Sancar was born in Savur, a small town in the Mardin province of southeastern Turkey. He was one of several children in a modest family. His parents had little or no formal schooling, but they placed great value on education for their children, and several of the siblings went on to study at university. Growing up in a region far from Turkey's big research centres, Sancar had few scientific role models, which makes his later path all the more remarkable.

Education and Mentors

He studied medicine at Istanbul University and graduated as a physician in 1969. He practised briefly as a doctor in rural Turkey, but he found that research attracted him more than clinical work. He read about photoreactivation, the strange recovery of UV-damaged bacteria by visible light, and decided to study it.

He moved to the United States and enrolled at the University of Texas at Dallas, where he earned his PhD in 1977. His doctoral work was on the enzyme photolyase, in the laboratory of Claud Rupert, who had done pioneering work on photoreactivation. Sancar succeeded in cloning the photolyase gene in the late 1970s. After postdoctoral work at Yale University, he joined the University of North Carolina at Chapel Hill in 1982, where he built his research career.

Career Timeline

Major Scientific Contributions

• Photolyase: cloned the gene, purified the enzyme and described how its flavin cofactor uses blue light to split cyclobutane pyrimidine dimers.
• Nucleotide excision repair in bacteria: demonstrated that UvrA, UvrB and UvrC together make two cuts around a lesion and release a short fragment, after which UvrD, DNA polymerase I and ligase complete repair.
• Human excision repair: reconstituted the human system in the test tube and showed how defects lead to xeroderma pigmentosum.
• Cryptochromes and the circadian clock: showed that photolyase-like proteins help regulate biological clocks.
• Transcription-coupled repair: contributed to understanding of how repair is directed to genes being actively transcribed.

For the details of the chemistry, read our companion post on the discovery of nucleotide excision repair.

Awards, Honours and Nobel Prize

The 2015 Nobel Prize in Chemistry was shared equally among Tomas Lindahl (base excision repair), Paul Modrich (mismatch repair) and Aziz Sancar (nucleotide excision repair), "for mechanistic studies of DNA repair". Sancar is a member of the United States National Academy of Sciences and holds a Kenan professorship at the University of North Carolina. He received many honorary degrees and awards from universities and societies in Turkey and abroad. He is one of the few scientists from Turkey to receive a science Nobel Prize.

Personality, Struggles and Lesser-Known Facts

• Medicine to molecules: He trained as a doctor but chose the laboratory, a change that surprised many in his family and community.
• A scientific couple: He is married to Gwen Boles Sancar, also a molecular biologist at the University of North Carolina. Together they have studied the circadian clock and photolyase relatives.
• Unfashionable topic: In the 1970s, photoreactivation was not a hot area. Sancar stayed with a difficult problem for decades, long before it became obviously important.
• Patience with purification: His breakthroughs came from careful, old-style biochemistry: growing bacteria in bulk, purifying proteins, and testing each in the dark and in light.
• Giving back: He and his wife established a foundation to support Turkish students studying in the United States and to strengthen cultural ties.

Legacy and Influence on Modern Chemistry

The idea that cells constantly repair their DNA is now basic textbook science. Sancar's work underpins understanding of why UV light causes skin cancer, why xeroderma pigmentosum patients must avoid sunlight, and why platinum anticancer drugs work better on some tumours than others. Drug developers now think about DNA repair pathways when designing cancer therapy. His discovery that photolyase-like proteins keep time in our cells also linked repair biochemistry to the study of sleep and daily rhythms.

Lessons for Students

1. Your starting point does not decide your finish. A child from a small Anatolian town became a Nobel laureate through education and persistence.
2. Stay with a hard question. Long projects often pay off in unexpected ways.
3. Learn techniques across fields. Sancar combined genetics, cloning and protein chemistry.
4. Choose problems that matter. DNA repair touches cancer, ageing and evolution.
5. Chemistry is everywhere in biology. For JAM and NET, think of enzymes as catalysts with mechanisms you can write down.

FAQ

Was Aziz Sancar a chemist or a biologist?

He is a biochemist. He trained in medicine, but his work is about the chemistry of enzymes acting on DNA, so the Nobel Committee awarded the prize in Chemistry.

Which university does he work at?

He has been a professor at the University of North Carolina at Chapel Hill since 1982.

Who shared the Nobel Prize with him?

Tomas Lindahl of Sweden and the United Kingdom, and Paul Modrich of the United States.

What should I remember for exams?

Remember the three Nobel winners and their pathways: Lindahl for base excision repair, Modrich for mismatch repair, Sancar for nucleotide excision repair and photolyase.

Published by ABC Chemistry — IIT-JAM | CSIR-NET | GATE Chemistry Coaching. Visit abcchemistry.com