The English biochemist Sir Frederick Gowland Hopkins (1861-1947) was the first to recognize the necessity for "accessory factors" in the diet, thereby initiating important work in vitamin research.
On June 20, 1861, F. Gowland Hopkins was born in Eastbourne, Sussex. He attended the City of London School at Enfield (1871-1875) but was forced to withdraw because of truancy caused by "sheer boredom, " to use his own words. He then attended a private school.
Hopkins was apprenticed for 3 years to a consulting analytical chemist in London. At the age of 20 he entered the Royal School of Mines at South Kensington, where he took a course in chemistry, and after some analytical practice he studied at University College, London, for the associateship of the Institute of Chemistry. In 1883 he became assistant to Thomas Stevenson, Home Office analyst and lecturer on forensic medicine at Guy's Hospital. Meanwhile, Hopkins began to read for his degree from the University of London, and then in 1888 he began to study medicine at Guy's Hospital. In 1894 he graduated from the University of London in both science and medicine and became an assistant in the department of physiology at Guy's Hospital. In 1898 he joined the physiological department at Cambridge University as a lecturer in order to develop teaching and research in physiological chemistry. That year Hopkins married Jessie Anne Stevens; the marriage resulted in three children.
Hopkins's task at Cambridge, supplemented by tutorial work at Emmanuel College, left him little time for research. In 1910 Trinity College granted him a fellowship and appointed him praelector in physiological chemistry, a position with no formal obligations other than his own research.
During his last few years, Hopkins, who was the ablest analyst and medical specialist in England, suffered from a number of increasing disabilities, including loss of sight. His life's work had been "the exploration of the chemistry of intermediary metabolism, and the establishment of biochemistry as a separate discipline concerned with this active chemistry of the life process, and not merely with its fuels and end-products." When he died at Cambridge on May 16, 1947, he had already seen this aim accepted by scientists throughout the world. As the undisputed dean of English biochemistry, which he had established almost single-handedly, Hopkins was the recipient of many honorary degrees, honors, and prizes, including fellowship in the Royal Society (1906), knighthood (1925), the Copley Medal (1926), and the Nobel Prize in physiology or medicine (1929).
Hopkins's first mature research paper concerned the chemistry of the pigments of butterflies' wings. His first work on this topic appeared in 1889, but his complete research was not published until 1896 in Philosophical Transactions of the Royal Society as "Pigments of Pieridae." Hopkins showed that the opaque white substance in the wings of this butterfly was uric acid—an example of the use of a normal excretory product for purposes of ornamentation. His research on butterfly pigments led him to extend his work to uric acid problems in humans. In 1893 he published two papers describing a new method for determining uric acid in urine, which remained standard practice for many years. He published papers in 1898 and 1899 on the relation of uric acid excretion to diet, a reflection of the interest at that time in gout and its relation to uric acid formation.
Hopkins had not been long at Cambridge when he produced a piece of classic research that immediately brought him to the forefront of physiological chemists. While investigating the cause of failure of the Adamkiewicz color test (now called the glyoxylic test) for proteins, he found that the reaction was due not to acetic acid itself but to glyoxylic acid, an impurity. He then used his analytical skill to discover what substance in protein gave this purple color and consequently isolated the hypothetical amino acid tryptophan from the other amino acids present in protein digests. Rather than turning to another subject, Hopkins began feeding experiments with mice to ascertain the role of the newly discovered tryptophan in the diet. He found that although the tryptophan did not make the mice grow, it extended their life-span considerably. This experiment, one of the earliest (1907) demonstrating the importance of quality of diet, was one of the essential classic tests which brought this aspect of nutrition to the attention of the scientific world.
Hopkins's work on vitamins, summarized in his 1912 publication "The Importance of Accessory Food Factors in Normal Dietaries, " is generally regarded as his masterpiece. Although other claimants for the honor exist, there is no doubt that Hopkins was the first to realize the full significance of the experimental facts about vitamins. His work had a far-reaching effect on nutritional research all over the world.
World War I interrupted Hopkins's research activities. His next major paper, "An Autoxidisable Constituent of the Cell, " was published in 1921. An intervening lecture, "The Dynamic Side of Biochemistry, " an address he gave as president of the Physiological Section of the British Association, is noteworthy in that in it Hopkins stated his outlook on chemical processes in living tissues. He pointed out that metabolic raw material is prepared so that it will be in the form of low-molecular-weight substances, and he underscored the importance of the new idea of endoenzymes as the universal agent of the cell. He also suggested greater use of the direct method of attack to separate from tissues additional examples of the simpler products of metabolic changes, regardless of the small amounts of these that were present.
During the 1920s the study of biological oxidations was dominated by two rival theories which were apparently incompatible: one assumed a process due to activation of pairs of hydrogen atoms by tissue enzymes called dehydrogenases; and the other assumed a process brought about by an oxygen-activating catalyst which contains iron. Both of these processes are now known to be valid, and Hopkins, to some extent, succeeded in reconciling them. He isolated a substance which he called glutathione and showed that it could exist in two interconvertible forms: a reduced form and an oxidized form. He proposed that glutathione functioned as an oxygen-carrying catalyst (called by him a coenzyme), with the disulfide oxidized form acting as the hydrogen acceptor in being reduced and then passing on the hydrogen to oxygen during its spontaneous reoxidation. This proposal seems to have furnished the first hint that intermediate hydrogen transport might occur in living tissues, a now well-established fundamental fact in the field of biological oxidation.
The true measure of Hopkins's importance lay not only in his own research but in the inspiration he provided to numerous biochemists who spread his teachings throughout the world. The number of his students elected to university chairs in biochemistry is particularly impressive. Perspectives in Biochemistry, published in 1937 in honor of his seventy-fifth birthday by a group of Hopkins's students, gives some idea of their productivity.
At the beginning of the 20th century, physiological chemistry and biochemistry were virtually a German monopoly. In England there were literally no biochemists and only a very few physiological chemists. At the time of Hopkins's retirement, British biochemists were the equal of any in the world.
Much useful information on Hopkins's life is in Joseph Needham and Ernest Baldwin, eds., Hopkins and Biochemistry, 1861-1947 (1949). Detailed studies of Hopkins's life and work are the memoir by Sir Henry Dale in the Royal Society, Obituary Notices of Fellows of the Royal Society, vol. 6 (1948-1949); James Gerald Crowther, British Scientists of the Twentieth Century (1952); and Patrick Pringle, Great Discoverers in Modern Science (1955).