HEF-bio.html Hermann Emil Fischer (1852-1919) German chemist who produced synthetic sugars and, from these, various enzymes. His descriptions of the chemistry of the carbohydrates and peptides laid the foundations for the science of biochemistry. He received the Nobel prize in 1902. About 1882, Fischer began working on a group of compounds that included uric acid and caffeine. He realized that they were all related to a hitherto unknown substance, which he called purine. Over the next few years he synthesized about 130 related compounds, one of which was the first synthetic nucleotide. These studies led to the synthesis of powerful hypnotic drugs derived from barbituric acids (barbiturates). Fischer was born near Bonn and educated there and at Strasbourg and Munich. He held professorships at Erlangen 1882-85, W?rzburg 1885-92, and Berlin from 1892. In 1884, Fischer discovered a key reaction in the study of sugars. He went on to determine the structures of glucose, fructose, mannose, and the group of sugars known collectively as hexoses. Fischer's investigations into the chemistry of proteins began 1899. He synthesized the amino acids ornithine (1,4-diaminopentanoic acid) 1901, serine (1-hydroxy-2-aminobutanoic acid) 1902, and the sulphur-containing cystine 1908. He then combined amino acids to form polypeptides. Selected Works Biography: Hermann Emil Fischer was born on October 9, 1852, at Euskirchen, in the Cologne district. His father was a successful businessman. His father wished him to enter the family lumber business, but Emil wished to study the natural sciences, especially physics. His father sent him in 1871 to the University of Bonn to study chemistry. In 1872, Emil, was persuaded by his cousin Otto Fischer, to go with him to the newly established University of Strasbourg, where Professor Rose was working on the Bunsen method of analysis. His Fischer met Adolf von Baeyer. Studying under von Baeyer, Fischer worked on the phthalein dyes which Rose had discovered and in 1874 he took his Ph. D. at Strasbourg with a thesis on fluoresceine and orcin-phthalein. In the same year he was appointed assistant instructor at Strasbourg University and here he discovered the first hydrazine base, phenylhydrazine and demonstrated its relationship to hydrazobenzene and to a sulphonic acid described by Strecker and Romer. Fischer continued to work on the hydrazines and, working there with his cousin Otto Fischer, who had followed him to Munich, he and Otto worked out a new theory of the constitution of the dyes derived from triphenylmethane, proving this by experimental work to be correct. At Erlangen Fischer studied the active principles of tea, coffee and cocoa, namely, caffeine and theobromine, and established the constitution of a series of compounds in this field, eventually synthesizing them. The work, however, on which Fischer's fame chiefly rests, was his studies of the purines and the sugars. This work, carried out between 1882 and 1906 showed that various substances, little known at that time, such as adenine, xanthine, in vegetable substances, caffeine and, in animal excrete, uric acid and guanine, all belonged to one homogenous family and could be derived from one another and that they corresponded to different hydroxyl and amino derivatives of the same fundamental system formed by a bicyclic nitrogenous structure into which the characteristic urea group entered. This parent substance, which at first he regarded as being hypothetical, he called purine in 1884, and he synthesized it in 1898. In 1884 Fischer began his great work on the sugars, which transformed the knowledge of these compounds and welded the new knowledge obtained into a coherent whole. Even before 1880 the aldehyde formula of glucose had been indicated, but Fischer established it by a series of transformations such as oxidation into aldonic acid and the action of phenylhydrazine which he had discovered and which made possible the formation of phenylhydrazones and the osazones. He established the relationbetween, glucose, fructose, and mannose, which he discovered in 1888. In 1890, by epimerization between gluconic and mannonic acids, he established the stereochemical nature and isomery of the sugars, and between 1891 and 1894 he established the stereochemical configuration of all the known sugarsand exactly foretold the possible isomers, by an ingenious application of the theory of the asymmetrical carbon atom of Van't Hoff and Le Bel, published in 1874. His greatest success was his synthesis of glucose, fructose, and mannose in 1890, starting from glycerol. This monumental work on sugars, carried out between 1884 and 1894, was extended by other work, the most important being his studies of the glucosides. Between 1899 and 1908 Fischer made his great contributions to knowledge of the proteins. He discovered a new type of amino acids, the cyclic amino acids: proline and oxyproline. He also studied the synthesis of proteins by obtaining the various amino acids in an optically-active form in order to unite them. He was able to establish the type of bond that would connect them together in chains, namely, the peptide bond, and by means of this he obtained the dipeptides and later the tripeptides and polypeptides. In 1901 he discovered, in collaboration with Fourneau, the synthesis of the dipeptide, glycyl-glycine and in that year he also published his work on the hydrolysis of casein. His synthesis of the oligopeptides culminated in an octodecapeptide, which had many characteristics of natural proteins. Fischer also studied the proteins the enzymes and the chemical substances in the lichens which he found during his frequent holidays in the Black Forest, and also substances used in tanning and, during the final years of his life, the fats. In 1888 Fischer married Agnes Gerlach. Unhappily his wife dies seven years after their marriage. They had three sons, one of whom was killed in the First World War; another took his own life at the age of 25 as a result of compulsory military training. The third son, Hermann Otto Laurenz Fischer, who died in 1960, was Professor of Biochemistry in the University of California at Berkeley. When Fischer died in 1919, the Emil Fischer Memorial Medal was instituted by the German Chemical Society. google kayıt google reklam google reklam google reklam google reklam görüntülü sohbet sesli chat sesli chat sesli chat sesli sohbet sesli sohbet site ekle