Dr. Klug held a PhD in physics but won the Nobel in 1982 for chemistry, for applying techniques from physics and mathematics to problems of molecular structure that could be regarded as within the domain of chemistry.
He was “a towering giant of 20th century molecular biology who made fundamental contributions to the development of methods to decipher and thus understand complex biological structures,” Venki Ramakrishnan, president of Britain’s Royal Society, said in a statement.
In great degree, Dr. Klug devised and demonstrated techniques of creating pictures of the arrangement of the atoms of crystalline substances in their three-dimensional, previously invisible reality. His work has had profound implications in the study of biology and medicine, including some forms of medical imaging.
Dr. Klug made use of one of the great dualities in science: the existence of electromagnetic radiation as both waves and particles, with each regarded as equally real.
In a sense, scientists probe crystals by bouncing beams of x-rays or of electrons off their atoms. They infer structure by charting the paths of the rebounds.
Shifting the angles at which the radiation strikes the crystal provides even more detailed information. Properly analyzed, through sophisticated mathematical techniques,, the patterns made by the reflected or diffracted radiation can produce a map of a molecule in its full three dimensions.
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Dr. Klug’s contribution was made possible, at least in part, by his mastery of many scientific techniques, and his ability to transfer methods from physics to the life sciences. Excursions beyond the boundaries of physics into other fields, biology in particular, were not so common, he once noted.
“Many physicists,” he observed, “hate the idea of anything wet and sloppy.”
Among the major contributions made by Dr. Klug and co-workers was to break down a substance called chromatin into fragments susceptible to study with diffracted X-rays and the beams of electron microscopy. It is in chromatin that DNA is packaged within living tissue.
Dr. Klug also worked on another molecule of fundamental importance, transfer RNA, and later in his career worked on proteins called zinc fingers, which are involved in switching genes off and on. His research has contributed to the understanding of Alzheimer’s disease and other forms of neurodegenerative disease.
In 1982, the Nobel committee awarded the chemistry prize to Dr. Klug “for his development of crystallographic electron microscopy and his structural elucidation of biologically important nucleic acid-protein complexes.”
Nucleic acids are fundamental building blocks of living matter; making known their structures has contributed to deeper insights into the mysteries of life.
Mapping the unseen in this manner can be regarded as the solution of a puzzle, and from childhood, Dr. Klug found himself drawn to puzzles.
He was born in Zelvas, Lithuania, on Aug. 11, 1926. He was 2 when his father, an artisan who also became involved in raising cattle, moved the family to Durban, South Africa, hoping to find a home more congenial to Jews.
One of Dr. Klug’s earliest fascinations was with Egyptology. Later, the book “Microbe Hunters” by Paul de Kruif, whetted an interest in science. In 1945, he graduated from the University of Witwatersrand in Johannesburg. Drawn by physics, he obtained a master’s degree from the University of Cape Town, followed by a PhD in solid state physics at Britain’s University of Cambridge in 1952.
In England, he worked at top-ranked institutions with some of the celebrated scientists of his era, including Rosalind Franklin, whose specialty was crystallography. Her work, which led to the discovery of the structure of DNA, has often been said to have been denied full recognition until after her death. Some have argued that her gender may have played a part in the delay in achieving recognition.
With Franklin, Dr. Klug worked on the structure of tobacco mosaic virus, a springboard to learning more about molecular structure. Through Franklin, he said, he learned something particularly important.
He said he had a tendency to disperse his energies in service to his wide-ranging curiosity. From Franklin, he learned how important it was at times “to be single-minded.”
Through Franklin, Dr. Klug became a friend of Francis Crick, who shared the Nobel Prize with James Watson and Maurice Wilkins in 1962 for discovering the structure of DNA.
Crick helped Dr. Klug’s research group became part of a molecular biology lab at Cambridge. In 1968, Dr. Klug and his collaborators announced the technique of Fourier electron microscopy, showing how seemingly limited data could permit three-dimensional molecular reconstructions. The discovery revealed the structures of hundreds of molecules and produced nothing less than a revolution in the field of structural molecular biology.
In 1986, Dr. Klug became director of the Cambridge molecular biology laboratory, serving until 1996. He was also president from 1995 to 2000 of Britain’s venerable Royal Society, the world’s oldest scientific organization, whose members have included Isaac Newton, Charles Darwin and Albert Einstein.
A knighthood in 1988 made him Sir Aaron Klug.
In 1948, Dr. Klug married dancer and choreographer Liebe Bobrow; they had two sons and several grandchildren. Complete information about survivors was not available.
“Almost everything I’ve worked on,” Dr. Klug once said “after I started, other people moved in and did all sorts of useful work, but by then I’d moved on to something else.”
The reason, he said in a comment implying the genuine enjoyment provided by science, was that “people jump in when they see something good and spoil the fun, really.”