Alexander Todd
Todd, Alexander, also known as Lord Todd, (1907-1997) was a British biochemist who contributed to the understanding of the protein composition of cells. For this work, he was awarded the Nobel Prize in chemistry in 1957. Much of his life's research concerned the chemistry of natural substances.
Alexander Robertus Todd was born Oct. 2, 1907, in Glasgow, Scotland. His parents were Alexander Todd, a businessman, and Jane (Lowrie) Todd. Todd studied at Glasgow University and then at the University of Frankfurt-am-Main in Germany. He obtained his first doctorate at Frankfurt on the chemistry of bile acids in 1931. The liver uses cholesterol to make bile acids, which aid digestion. He then studied at Oxford University in England under Sir Robert Robinson, a British organic chemist, who received the 1947 Nobel Prize in chemistry. Robinson found the structure and behavior of many important natural substances, including the red and blue pigments of flowers; alkaloids, such as morphine and strychnine; hormones; and penicillin. He also developed methods for synthesizing (making artificially) many of these substances. Todd received his second Ph.D. degree on the chemistry of natural pigments from Oxford in 1933.
Todd held a two-year post at Edinburgh University in the medical chemistry department, where he worked on the chemistry of vitamin B. He then went to the Lister Institute of Preventive Medicine in London. Todd also researched alkaloids. An alkaloid is any of a group of organic bases found in plants. Alkaloids contain carbon, hydrogen, nitrogen, and oxygen. Small amounts of many alkaloids can have a powerful effect on people and animals and are used as medicines or poisons. Some useful alkaloids are synthesized in chemical factories, as well as taken from plants.
While at the Lister Institute, Todd studied the alkaloids derived from Cannabis sativa, the scientific name for the hemp plant. Marijuana is a drug made from the dried leaves and flowering tops of the hemp plant, and contains more than 400 chemicals. If smoked, marijuana produces over 2,000 chemicals that enter the body through the lungs. These chemicals create many psychological and physical effects. Todd discovered that cannabinol, a compound in marijuana, had useful medicinal qualities and could be separated from the narcotic resin in the plant.
In 1937, Todd became reader in biochemistry at the University of London, and in 1938 he became professor of chemistry at the University of Manchester and director of the chemical laboratories. He began teaching organic chemistry at Cambridge University in 1944. There he remained until his retirement in 1971. During that time, he became both a fellow and a master of Christ's College at Cambridge.
From the late 1930's until the mid-1940's, Todd investigated nucleotides and nucleosides, compounds out of which the nucleic acids deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are built. These nucleic acids are complex molecules found in all living cells. DNA is found mainly in the nucleus of cells, and RNA may be found throughout the cell. DNA is the hereditary material of an organism. Short sections of DNA called genes determine an organism's characteristics.
Todd discovered that nucleotides were formed by sugar molecules and phosphate groups that attached themselves to four known chemical bases of DNA—adenine, guanine, thymine, and cytosine. Todd's work in this field prepared the way for the model of DNA devised by American biologist James Dewey Watson and British biologist Francis H. C. Crick. Watson and Crick devised a model of the molecular structure of DNA in 1953. They proposed that the DNA molecule consists of two chains of polynucleotides arranged in a double helix (spiral). Polynucleotide chains of phosphates and sugars form the sides of the ladder. The matching bases, called base pairs, are the rungs that hold the chains together. The two chains are held together by weak chemical bonds between specific pairs of bases. For example, an adenine base on one polynucleotide chain always bonds with a thymine base on the other chain. Similarly, guanine on one chain always bonds with cytosine on the other chain. The DNA molecule looks like a twisted rope ladder.
RNA is similar in structure to DNA. Like DNA, RNA consists of long chains of nucleotide units. However, the sugar in RNA is ribose, rather than deoxyribose, and the bases are adenine, guanine, cytosine, and uracil rather than thymine. RNA plays an important role in the formation of proteins.
Todd also synthesized three important compounds—adenosine triphosphate, flavin adenine dinucleotide, and uridine triphosphate—between 1949 and 1954. Adenosine triphosphate (ATP) is a compound of adenosine and three phosphate groups. The removal of phosphate releases large amounts of energy which are used for biological reactions, for example, in muscle contraction and the metabolism of sugars.
Flavin adenine dinucleotide (FAD) plays a role in the breakdown of glucose molecules, an important step in aerobic metabolism. Uridine triphosphate (UTP) is a nucleotide that plays a role in RNA and in the metabolism of sugars.
Todd's other work included exploring the structure of such substances as vitamins B1. E. and B12. Early in his career, he developed a method for synthesizing vitamin B1, or thiamine, that is still used to manufacture it today. The body needs thiamine to change carbohydrates from food into energy. It helps the nervous system function properly. This vitamin is needed for growth. Sources of thiamine include legumes, nuts, organ meats, pork, whole grains, and most vegetables.
In the late 1930's, Todd did research in vitamin E, or tocopherol. This vitamin helps prevent polyunsaturated fatty acids from oxidizing (combining with oxygen). Vitamin E thus plays an important role in maintaining cell membranes, which contain substantial amounts of polyunsaturated fatty acids. Sources of vitamin E include seed oils, vegetable oils, wheat germ, and whole grains.
In 1955, he announced his and his team of Cambridge chemists' discovery of the structure of vitamin B12, also called cobalamin. Vitamin B12 is essential for the normal functioning of folic acid, and it helps proper function of the nervous system. Vitamin B12 and folic acid are needed to produce DNA in the body's cells. Eggs, fish, meat, milk, and poultry, as well as some microbes, supply vitamin B12.
Todd won the 1957 Nobel Prize in chemistry “for his work on nucleotides and nucleotide coenzymes.” An enzyme is a molecule that speeds up chemical reactions in all living things. Organic compounds called coenzymes attach to the protein part of an enzyme. In that formation, the coenzyme and the protein function together. Many coenzymes consist of vitamins, especially B vitamins. If a person's diet lacks adequate amounts of these vitamins, the enzymes cannot function properly, and various body disorders may develop.
During World War II (1939–1945), Todd worked on military projects, especially helping to develop and produce chemical warfare agents.
Todd was elected to the Royal Society in 1942 and served as its president from 1975 to 1980. Queen Elizabeth knighted Todd in 1954 for distinguished service to the government. He was named Baron Todd of Trumpington in 1962. He served as the first Chancellor of the University of Strathclyde from 1965 to 1991. He was awarded the Order of Merit in 1977 and made a Life Peer in 1962. In 1983, he published an autobiography, A Time to Remember: The Autobiography of a Chemist. Todd acted as trustee for various charities and as a member of many government committees. From 1952 to 1964, he served as chairman of the advisory council on scientific policy to the British government.
Todd taught as a visiting professor at the University of Sydney in Australia and in the United States at the California Institute of Technology, the University of Chicago, and the Massachusetts Institute of Technology. He received medals from the French Chemical Society and the Royal Society and was a member of the National Academy of Sciences.