Sir Hans Adolph Krebs

Hans Adolph Krebs was born on August 25, 1900 in Hildesheim, Germany. He was the second child of Georg Krebs, an ear/nose/throat doctor and a biochemist, and his wife Alma. Krebs attended the local grammar school and was briefly conscripted into the German imperial army at the end of World War I. Krebs then studied medicine at the University of Gottingen and the University of Freiburg, and earned his PhD from the University of Hamburg in 1925. He studied chemistry in Berlin for a year and then took a job as an assistant to Otto Warburg at the Kaiser Wilhelm Institute for Biology. He remained there until 1930 when, after briefly doing clinical work in Altona, Germany, he returned to the University of Freiburg, where working with Kurt Henseleit he described the urea cycle, which take place in the mammalian liver. The urea cycle is how mammals remove ammonia (which is toxic in large amounts), from amino acid metabolism, converting it into urea which is excreted by the kidneys.

With the election of Adolph Hitler and the rise of the National Socialist (Nazi) Party in 1933 Krebs was dismissed from his position because of his Jewish heritage. After his dismissal Krebs emigrated to England where he took a position at Cambridge University sponsored by a Rockefeller Foundation Studentship grant. In 1935 he was appointed as a lecturer in pharmacology at Sheffield University and in 1938 he was made lecturer-in-charge of Sheffield University's newly founded department of biochemistry. In 1945 the appointment was raised to a professorship and he took charge of the Medical Research Council's research unit established at the university. In 1954 he was appointed as the Whitley Professor of Biochemistry at Oxford University.

Krebs' major research accomplishment was elucidating the citric acid cycle (also called the Krebs cycle or the tri-carboxcylic acid cycle.)  The citric acid cycle, which takes place in the mitochondrial matrix (inside the mitochondrial inner membrane) in eukaryotes and in the cytosol of  prokaryotes, is a cyclic reaction cycle that produces reduced equivalents that are used to produce cellular energy. It is the final set of reactions of cellular metabolism by which organisms break down carbohydrates producing energy and releasing carbon dioxide (for a video showing the series of reactions by which carbohydrates are broken down, highlighting the citric acid cycle, to make cellular energy see here). For his discovery of the citric acid cycle Krebs shared the 1953 Nobel Prize in physiology and medicine with Fritz Lipmann.

Other honors won by Krebs include a knighthood in 1958 and election as a honorary fellow of Girton College, Cambridge University in 1979.

Krebs died on November 22, 1981.


References:

Stubbs, Marion and Gibbons, Geoff; "Hans Adolph Krebs (1900-1981)...His Life and Times"; IUBMB Life (2000)50:163-166

Hans Krebs Nobel Biography

Hans Adolph Krebs Wikipedia Entry

Julius Lothar Meyer

Julius Lothar Meyer was born on August 19, 1830 in Varel, which at the time was part of the Dutchy of Oldenburg, and is now part of Germany. He was the fourth of seven children of a physician and his wife. He began his education with the intention of following his father in his career choice and after high school he studied medicine first at Zurich University and then at the University of Wurzburg. He qualified in medicine in 1854. After graduation, interested in physiological chemistry, Meyer worked at the University of Heidelberg, where Robert Bunsen was the chemistry department chair. He earned his Ph.D. from the University of Breslau in 1858, completing a thesis on the action of carbon monoxide on blood. The following year he became a privat-docent in physics and chemistry at Breslau. In 1866 Meyer became professor of chemistry at Karshule Polytechnic and in 1876 he became the first professor of chemistry at the University of Tubingen, where he remained until his death.

Meyer is chiefly remembered for his contributions to the development of the periodic table of elements. In 1864 Meyer published Die Modernen Theorie der Chemie, a chemistry textbook that went through five editions and was translated into English, French, and Russian. Included in the book was a table of 28 elements arranged by increasing atomic mass. Meyer was the first to identify the periodic (repeating) nature of the elements. Periodicity means that chemical elements of different sizes can have similar properties and those properties are repeating in that elements listed on the periodic table in groups (vertical columns) have similar chemical properties. Meyer's publication preceded Dimitri Mendeleev's periodic table (from which the modern periodic table was developed) which was not published until 1869. Like Mendeleev's table Meyer's table has empty spaces for elements that had not been discovered yet.

Meyer is also known for being the first to predict that benzene had a cyclic shape, although he did not predict the alternating single/double bonds found in benzene, that were later described by August Kekule. In 1882, Meyer (with Mendeleev) was awarded the Davy Medal by the Royal Society of London.

Meyer died on April 11, 1895.


References:

The Royal Society of Chemistry: "Julius Lothar Meyer -- The First Identifier of Periodicity?"; retrieved from rsc.org

Daintith, John; "Meyer, Julius Lothar" in the Biographical Encyclopedia of Scientists, Third Edition; CRC Press; 2010

Scerri, Eric; A Tale of Seven Elements; Oxford University Press; 2013

Julius Lothar Meyer Wikipedia Entry

Cato Maximilian Guldberg

Cato Maximilian Guldberg was born on August 11, 1836 in Christiania (now Oslo) , Norway. He was educated at the University of Christiania. Starting in 1860 he taught mathematics at the Royal Military School. Later he became a professor of applied mathematics at the University of Christiana.

In 1863, working in collaboration with his brother-in-law Peter Waage (with whom he is pictured above, Guldberg is on the left) he formulated the law of mass action. This is a chemical law that says that the rate of any chemical reaction is proportional to the concentration of the reacting chemical(s). So for the chemical reaction A + B -> C, the rate of the reaction will be a constant (k) times the concentrations of A and B, such that rate = k[A][B], where [A] and [B] are the concentrations of A and B. Guldberg and Waage also investigated the effects of temperature on chemical reaction rates. Because Guldberg and Waage published in Norwegian the law of mass action when first published was largely ignored. When it was republished in French it still drew little attention until it was experimentally demonstrated by William Esson and Vernon Harcourt working at Oxford University.

Starting in 1870 Gulberg investigated how a dissolved substance affects the freezing point and vapor pressure of a pure liquid. In 1890 he formulated Guldberg's law which says that the boiling point of a liquid is two thirds the temperature of its critical temperature, the temperature at which a gas cannot be liquefied by increased pressure alone.

Gulberg died on January, 14, 1902 in his native city, which had respelled it's name to Kristiania.


References:

Daintith, John; "Guldberg, Cato Maximilian (1836-1902)" in Biographical Encyclopedia of Scientists, Third Edition; CRC Press; 2010

Tilden, Sir William Augustus; "Cato Maximilian Guldberg" in The Progress of Scientific Chemistry of Our Times; Longmans, Green; 1913

Cato Maximilian Guldberg Wikipedia Entry

John Wrottesley, Second Baron Wrottesley

John Wrottesley was born on August 5, 1798, near Woverhampton, in central England. Wrottesley was the eldest son of Sir John Wrottesley and his first wife Lady Carolyn Bennet. Wrottesley attended Westminster School from 1810 to 1814. He graduated first class in mathematics from Corpus Christi College, Oxford in 1817. He began building an observatory in Blackheath in 1829 and began making observations in 1831 cataloging the right ascensions of 1318 stars.

Because the celestial sphere of stars are stationary with respect to an orbiting and rotating Earth their position in the sky can be measured using a system of two coordinates, right ascension and declination. Right ascension is measured in hours and minutes and is the equivalent of terrestrial longitude on the celestial sphere. The other coordinate used identify star positions used with right ascension is declination. This is the angle in degrees from the equator of the celestial sphere that a star is. The equator of the celestial sphere is directly above the Earth's equator. For his catalog of stars' right ascensions Wrottesley was awarded a gold medal by the Royal Astronomical Society in 1839.

Wrottesley inherited his father's title as Baron Wrottesley in 1841. With his elevation to Baron he moved his observatory from Blackheath to his new home at Wrottesley Hall. He served as president of the Royal Astronomical Society from 1841 to 1842. He served as president of the Royal Society from 1854 to 1858. A crater on the moon is named after Wrottesley.

Wrotteseley died on October 17, 1867.


References:

Anon.; Obituary; Monthly Notices of the Royal Astronomical Society (1867)28:181-185

Carlyle, Edward Irving; "Wrottesley, John 1798-1867"; in Dictionary of National Biography 1885-1900 Vol. 63. Retrieved from: en.wikisource.com

John Wrottesley, Second Baron Wrottesley Wikipedia Entry