Professor Dr. Aziz Sancar (born 8 September 1946, Savur, Mardin) is a Turkish scientist, biochemist, molecular biologist and academic. He is among the leading figures in modern molecular biology due to his pioneering research in DNA repair, cellular sequencing, biological clocks and cancer therapy. In 2015, he was awarded the Nobel Prize in Chemistry jointly with Paul Modrich and Tomas Lindahl by the Royal Swedish Academy of Sciences for their mechanistic studies of DNA repair.

Sancar continues his research as a faculty member in the Department of Biochemistry and Biophysics at the University of North Carolina at Chapel Hill in the United States.

Early Life and Family

Aziz Sancar was born on 8 September 1946 in the district of Savur, Mardin, as the seventh child of a farming family with eight children. His father, Abdulgani Sancar, was a farmer, and his mother, Meryem Sancar, despite being illiterate, was deeply determined to ensure her children received an education. From an early age, she instilled in them the value of learning by repeatedly telling them, “You must read and study,” and played a decisive role in ensuring all her children completed higher education.

The House Where Aziz Sancar Was Born – Mardin (Anadolu Agency)

Sancar’s childhood unfolded in a small garden surrounded by almond, walnut and plum trees, in the rural setting of Mardin. The harsh conditions of rural life instilled in him the values of hard work and discipline at an early age. Sancar spent most of his days working in the fields with his father and siblings, and in his childhood memories, he associated the blooming trees of spring in his hometown with paradise.

His family lived in modest economic conditions. However, the family’s strong commitment to education shaped Sancar’s life path. His eldest brother, Kenan Sancar, rose to the rank of brigadier general in the Turkish Armed Forces and served as a model of discipline and perseverance for his younger sibling. Aziz Sancar learned to read and write from his brother at the age of five and entered primary school already far ahead of his classmates.

Aziz Sancar’s Primary School Years (Ministry of National Education)

Sancar has stated that he particularly enjoyed mathematics, chemistry, Turkish and French during his early education. During high school, under the guidance of his teacher Melahat Şahinoğlu, his interest in science deepened and prepared him for a lifelong scientific journey.

Sancar completed his secondary education at Mardin High School, where he excelled in the sciences and also served as the goalkeeper for the school football team. Although he was invited to try out for Turkey’s national under-18 football team, he chose to focus on his academic goals and gave up football.

Aziz Sancar’s Years Involving Football (Ministry of National Education)

University Years

In 1963, Sancar enrolled at the Faculty of Medicine, Istanbul University. Entering one of the country’s most prestigious medical schools from a small town in Anatolia marked a major cultural and academic turning point for him. Interacting with students from diverse ethnic and religious backgrounds broadened his worldview. During his student years, Sancar devoted himself entirely to his studies and avoided entertainment and social activities, describing this period as “years of intense discipline in study.”

Biochemistry courses particularly captured his interest, and learning about the double-helix structure of DNA in his second year became a life-changing milestone.

After graduation, he expressed his desire to pursue academic research to his professors, including Prof. Mutahhar Yenson, who advised him to first gain clinical experience as a physician. Taking this advice to heart, Sancar returned to his hometown after graduation and worked as a doctor for two years. He graduated first in his class in 1969.

Aziz Sancar’s Years at Istanbul University Faculty of Medicine (Ministry of National Education)

Medical Practice (1969–1971)

After graduation, Aziz Sancar returned to his hometown of Savur and provided free medical care from his home for a period, before being appointed by the Ministry of Health as the chief physician in the village of Sürgücü. During this time, he traveled to remote villages to deliver medical services and was often the first doctor many patients had ever seen. It is known that he devoted a significant portion of his income to purchasing medicine and toys for children.

He described this period as “the happiest years of his life”^【1】. However, clinical practice did not satisfy his scientific curiosity; he decided to return to the laboratory to understand the biological processes underlying disease.

Aziz Sancar’s Years as a Physician in His Hometown of Savur (Ministry of National Education)

Doctoral Years and Photolyase Research

In 1971, after winning a TÜBİTAK-NATO scholarship, Sancar went to Johns Hopkins University to pursue a doctorate in biochemistry. However, due to language and adaptation difficulties, he left the program and returned to Turkey. In 1973, he resumed his academic work at the University of Texas at Dallas (UTD) under the supervision of Prof. Claud S. Rupert.

Rupert was the scientist who discovered the photolyase enzyme in 1958. Sancar used molecular cloning techniques to isolate the photolyase (phr) gene in the bacterium E. coli to explain how this enzyme absorbs light and repairs DNA. The cloning of this gene illuminated the molecular mechanism of DNA repair enzymes. This work is regarded as foundational in the field of DNA repair research.

During this period, Sancar faced severe financial hardship and lived in the laboratory for long stretches. Without a scholarship and with his advisor’s permission, he worked around the clock, slept in the lab and showered using the fire hose. He devoted all his time and energy to his scientific work. In 1977, he completed his doctoral thesis, taking a lasting step into the world of science.

Aziz Sancar’s Early Years in the United States (Ministry of National Education)

Yale University and Discoveries in DNA Repair

Between 1977 and 1982, Sancar continued his research at the Yale University School of Medicine, focusing on nucleotide excision repair. He developed a method called “Maxicell,” which simplified the identification of proteins encoded by plasmids. This method became widely used in molecular biology during the 1980s. During the same period, he cloned the bacterial genes UvrA, UvrB and UvrC involved in DNA repair and identified the proteins they encode.

In experiments conducted in 1982, he demonstrated that damaged regions of DNA are repaired through a double-strand cleavage mechanism and developed the ABC excinuclease model to explain this process. This discovery became a fundamental reference in DNA repair research.

University of North Carolina and the Resolution of Photoreactivation

In 1982, Aziz Sancar joined the faculty of the University of North Carolina at Chapel Hill together with his wife, Gwen Boles Sancar, where he established his own laboratory. He discovered that the photolyase enzyme carries two different chromophores (FADH– and MTHF), one of which collects light like an antenna while the other carries out the repair reaction.

These studies were regarded as the culmination of over four decades of photolyase research, and in a 2011 publication, the complete sequence of steps in the mechanism was fully defined.

Transcription-Coupled Repair and the TRCF Factor

In the mid-1980s, Sancar turned his attention to the relationship between DNA repair and transcription. He investigated how RNA polymerase affects repair at damaged DNA regions and identified a protein he named the Transcription-Repair Coupling Factor (TRCF). This discovery revealed that DNA repair is not merely a genetic process but a mechanism coordinated with cellular functions. Sancar described this work as “my most aesthetically satisfying scientific research.”

DNA Repair in Human Cells and the “Piri Reis Map”

In the early 1990s, Sancar conducted research to map DNA repair in human cells. In 1991, he demonstrated that a 27-base-pair segment of human DNA is removed via a double-strand cleavage mechanism, proving that the bacterial repair process has a similar counterpart in humans. In 1994, the journal Science named DNA repair the “Molecule of the Year.”

In subsequent work, he mapped DNA repair regions in the human genome at single-nucleotide resolution and named these findings the “Piri Reis Map.” This method opened new horizons in chemotherapy and cancer biology research.

Research on Cryptochrome and the Biological Clock

In 1996, when sequences similar to the photolyase gene were discovered in the human genome, Sancar proposed that these genes might have a new light-related function. His research confirmed that these genes encode the cryptochrome (CRY1, CRY2) proteins that regulate the biological clock. Thus, the genetic basis of circadian rhythms in mammals was elucidated.

This discovery revealed connections between the biological clock and cancer development, cell repair and drug efficacy. Sancar’s team strengthened the scientific foundation of “chronotherapy” by demonstrating that DNA repair and cellular responses to chemotherapy vary depending on the time of day.

Awards

Sancar has received numerous national and international awards for his scientific contributions. His major honors include:

• National Science Foundation Young Investigator Award (1984)
• American Society for Photobiology Award (1990)
• National Institutes of Health Award (1995)
• TÜBİTAK Science Award (1997)
• Election to the American Academy of Arts and Sciences (2004)
• Election to the U.S. National Academy of Sciences (2005)
• Election to the Turkish Academy of Sciences (2006)
• Vehbi Koç Award (2007)
• Nobel Prize in Chemistry (2015)

Nobel Prize and Subsequent Research

Aziz Sancar was awarded the 2015 Nobel Prize in Chemistry for his long-term research elucidating the molecular mechanisms of DNA repair. The prize was presented on 10 December 2015 in Stockholm by His Majesty King Carl XVI Gustaf of Sweden.

Sancar donated his Nobel Prize to the Anıtkabir Atatürk and War of Independence Museum. The medal and certificate are now on display at Anıtkabir.

Scientific Contributions and Publications

Throughout his career, Aziz Sancar has published over 400 scientific articles and more than 30 book chapters. His research has brought significant innovations to the fields of DNA repair, photoreactivation, transcription-coupled repair, biological clock genes and cancer biology. His findings have contributed to the understanding of fundamental biological mechanisms governing the cell cycle and genetic stability.

Role in Scientific Communities and Contributions

In 2005, Sancar became the first Turkish scientist elected to the U.S. National Academy of Sciences, and in 2006, he became a full member of the Turkish Academy of Sciences. Alongside his scientific productivity, he exemplifies an academic demeanor that inspires young researchers.

Together with his wife, Professor Gwen Boles Sancar, he founded the Aziz & Gwen Sancar Foundation and opened the Carolina Turkish House to support Turkish students in the United States. This institution has become both a cultural center for Turkish students and a symbol of strengthened academic ties between the two countries.

Personal Life

Aziz Sancar married American biochemistry professor Gwen Boles Sancar, also a scientist, in 1995. The couple worked together for many years at the University of North Carolina at Chapel Hill, where they met. Gwen Sancar has conducted research in cell biology and DNA repair and has supported many of Aziz Sancar’s scientific projects. After converting to Islam, Gwen Boles Sancar adopted the name “Güven.”

Aziz Sancar and His Wife Gwen Boles Sancar – 1978 (Ministry of National Education)

Aziz Sancar’s life story is the tale of a determined scientist who rose from a rural Anatolian village to the global stage of science. Discipline, patience and unwavering dedication to science form the foundation of both his personal achievements and his contributions to Türkiye’s scientific legacy.

Sancar’s research on DNA repair and the biological clock has created a lasting transformation in biochemistry, genetics and medicine, strengthening the scientific basis of cancer treatment strategies. Today, he remains an active researcher, continuing to inspire new generations through his scientific curiosity and passion for teaching.