Maclyn McCarty, 93, a Rockefeller University physician and microbiologist who was the last surviving member of a three-person team that made one of the most momentous discoveries in the history of genetics, died Jan. 2 of congestive heart failure at St. Luke's Roosevelt University Hospital in New York City.
In 1944, Dr. McCarty and his colleagues, Oswald T. Avery and Colin MacLeod, demonstrated that deoxyribonucleic acid -- DNA -- and not protein is the substance that transmits genetic traits. This seminal discovery helped launch the field of molecular biology and laid the groundwork for Francis Crick and James Watson's discovery of DNA's double helix structure.
The work of the Rockefeller team built on an earlier discovery by an English bacteriologist named Frederick Griffith, who, investigating the bacterium that causes pneumonia, showed that an organism such as the pneumococcus bacterium could be altered and that the alteration could be passed on to succeeding generations. Dr. McCarty and his colleagues demonstrated how that transformation took place.
Dr. McCarty, the junior member of the group, used his skills at purification to produce in a test tube a highly refined substance consisting of DNA uncontaminated with protein. The team's work was the first direct evidence that DNA -- known since 1869 but thought to lack the necessary chemical complexity -- is responsible for genetic continuity.
Nine years later, Crick and Watson, along with Maurice Wilkins, deduced DNA's structure, for which they won the Nobel Prize in 1962. Although the work of Dr. McCarty and his collaborators was described by Nobel laureate Joshua Lederberg as "the pivotal discovery of 20th century biology," the three scientists never received the widespread recognition that Watson and Crick garnered.
"The reason they [Crick and Watson] were obviously interested in studying the structure of DNA was because of our work," Dr. McCarty told Newsday in 2003. He said that he was disappointed initially by the lack of recognition but that he had too much work to do to dwell on it.
Watson himself apologized in 2003 for not citing the Rockefeller team's work.
Maclyn McCarty was born in South Bend, Ind. He graduated from Stanford University in 1933 and received his medical degree from Johns Hopkins University in 1937. He was a medical fellow, doing research on sulfonamide drugs, at New York University in 1940-41, before joining what was then known as the Rockefeller Institute for Medical Research.
From 1942 to 1946, he was on active duty as a lieutenant commander in the Navy Medical Corps, working with the Naval Medical Research Unit based at the Rockefeller Institute Hospital. He was named an associate at Rockefeller in 1946.
In addition to his DNA research, Dr. McCarty was an expert on the Group A streptococcus, which causes rheumatic fever, a disease that destroys the heart valve and afflicts mostly children. His chemical analysis helped to make streptococci one of the most thoroughly understood of the disease-causing bacteria.
From 1960 to 1974, he was physician in chief of Rockefeller University Hospital. He became a vice president of the university in 1965 and was named a John D. Rockefeller Jr. professor in 1977. He retired as vice president in 1978 but held the Rockefeller chair until 1981, when he became professor emeritus.
Although he never won the Nobel Prize his peers believed his work deserved, he received America's most prestigious scientific prize, the 1994 Albert Lasker Award for Special Achievement in Medical Science, among many other honors. He also was the author of "The Transforming Principle" (1983), a chronicle of his landmark discovery.
Survivors include his wife, Marjorie McCarty of New York City; three children, Richard E. McCarty of Baltimore, Colin Avery McCarty of Clifton Park, N.Y., and Dale Dinunzio of Bradenton, Fla.; eight grandchildren; and five great-grandchildren.