Entering St. John's College, Cambridge, in 1936, he graduated with the degree of bachelor of arts (in natural sciences) in 1939. In 1943 he received his doctorate of philosophy (in chemistry) with a thesis on lysine.
He held a Beit Memorial Fellowship from 1944 to 1951 and then joined the staff of the Medical Research Council. He later became director of the Division of Protein Chemistry in the Council's Laboratory for Molecular Biology at Cambridge.
Sanger worked entirely on the chemical structure of the proteins, especially insulin. About 1900 Emil Fisher had succeeded in breaking down proteins into polypeptides, consisting of their ultimate constituents, amino acids. About 25 different amino acids occur in nature, and of these 20 are found in most mammalian proteins.
By 1943 it was known that proteins consisted of long chains of amino acid residues bound together by peptide linkages. A. C. Chibnall and others knew the 51 amino acid residues that composed insulin; they also knew that phenylalanine was at the end of one of the chains. The insulin molecule appeared to consist of a large number of polypeptide chains, and it was held that what was important biologically was the sequence in which the amino acids followed each other in the chains. This sequence was unknown for any protein.
Sanger introduced the reagent fluorodinitrobenzene (FDNB), which reacted with the free amino acid at the end of a chain to form a dinitrophenyl derivative (DNP) combined with that amino acid. The DNP acids were bright yellow. If the chains were then split by hydrolysis, the colored terminal acid of each link could be identified by chromatographic and electrophoretic methods. Sanger at first thought that the insulin molecule contained four long chains; but he later concluded that it consisted of only two chains containing 21 and 30 amino acids respectively. He then split the bridges joining the chains by oxidation with performic acid and dealt with each chain individually. The chain was separated into successively shorter links, and in each link the terminal amino acid was identified. He was able to determine the exact sequence of amino acids in each chain.
Sanger then determined that the two chains were linked by two disulfide bridges of cystine residues, with a third bridge linking two parts of the short chain. The determination of the exact positions of these bridges enabled Sanger, after over 12 years of research, to give a diagram for the structure of insulin. For this work he was awarded the Nobel Prize in Chemistry in 1958.
In 1980 Sanger shared the Nobel Prize for Chemistry with two other scientists for work determining the sequences of nucleic acids in DNA molecules. Their combined work has been lauded for its application to the research of congenital defects and hereditary diseases. It also proved vitally important in producing the artificial genes that go into the manufacture of insulin and interferon, two substances which are used to treat a variety of diseases. Sanger retired from research in 1983.
"Scientific research is one of the most exciting and rewarding of occupations. "
"I and my colleagues here have been engaged in the pursuit of knowledge. "
"I believe that we have been doing this not primarily to achieve riches or even honour, but rather because we were interested in the work, enjoyed doing it and felt very strongly that it was worthwhile. "
In 1954 he was elected a Fellow of the Royal Society and a Fellow of King's College, Cambridge; and in 1958 he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences.
He was a member of the Peace Pledge Union.
In 1940, he got married to Margaret Joan Howe, after they met through the Cambridge Scientists' Anti-War Group. Fred and Margaret had two sons and one daughter.