Wolf Prize Laureate in Medicine 1990
Affiliation at the time of the award:
Rockefeller University, USA
“for his part in the demonstration that the transforming factor in bacteria is due to deoxyribonucleic acid (DNA) and the concomitant discovery that the genetic material is composed of DNA”.
In the 1940’s when Drs. Avery, Macleod and McCarty first began to work on transformation of pneumococcus, not very much was known about the chemical nature of genetic material. It was known that heredity is determined by chromosomes and that c chromosomes contain DNA and proteins in about equal amounts. Since proteins are complex molecules composed of many different amino acids, while DNA is composed of only four different nucleotides, the general feeling in the early 1940’s was that proteins were intrincate enough to contain the genetic information, and DNA with its simplistic structure was considered to be almost irrelevant to genetics. Drs. Avery, Macleod and McCarty studied the two types of pneumococci giving rough and smooth colonies. They succeeded in making extracts of one bacterial type and to treat cells of the other bacterial type with the extracts, with the result that bacteria previously giving rough colonies now gave smooth colonies. This change of phenotype was called transformation. Although the chemistry of proteins and nucleic acids was not particularly developed at that time, McCarty was able to show that the only material required for transformation was deoxyribonucleic acid. These papers, published in 1944 and 1945, laid the foundation of our knowledge on the chemical basis of genetic information.
It is also not too much to say, that modern molecular biology is totally dependent on the knowledge of what the genetic material is. When it became known that it was deoxyribonucleic acid, it then became possible to do a whole variety of experillel1ts which have led to precise identification of the structure and functions of many genes in a variety of species, including man. Molecular genetic research carried out in the past decades fundamentally broadened our understanding of the processes of life.