The Characterization of Ferritin and Apoferritin by Leonor Michaelis and Sam Granick
Year: 2004
Type: article
Abstract: Ferritin. I. Physical and Chemical Properties of Horse Spleen Ferritin (Granick, S. (1942) J. Biol. Chem. 146, 451–461) Ferritin. II. Apoferritin of Horse Spleen (Granick, S., and Michaelis, L. (1943) J. Biol. Chem. 147, 91–97) Leonor Michaelis (1875–1949) was born in Berlin, Germany. He received his doctorate from Berlin University in 1897 and then became a private assistant to Paul Ehrlich in Berlin where he devised a method for in vivo mitochondrial staining with Janus green. After working for Moritz Litten and later Ernst Viktor von Leyden, Michaelis accepted a position at the Urban Hospital in Berlin. There he worked on a variety of bacteriology and physicochemical problems, including developing the hydrogen electrode to measure hydrogen ion concentration (pH). In 1912, Maud Leonora Menten (1879–1960), one of the first Canadian women to become a doctor, came to Berlin to spend a year working with Michaelis. In Berlin, she studied the effects of substrate concentration on invertase enzyme activity and devised an equation with Michaelis to describe the relationship between reaction rate and substrate concentration (1Michaelis L Menten M.L. Die Kinetik der Invertinwerkung.Biochem. Z. 1913; 49: 333Google Scholar). The Michaelis-Menten Equation has been called the foundation of modern enzymology and is now a standard for most enzyme-kinetic measurements. After her time in Berlin, Menten went to the University of Chicago and earned a Ph.D. in biochemistry. In 1918 she joined the Department of Pathology at the University of Pittsburgh medical school and published more than 70 papers during her time there. Despite her productivity, Menten was not promoted to full professor until 1948, one year before she retired from her position at the University of Pittsburgh. 1All the biographical information on Maud Menten was taken from Ref. 11Skloot R. Some called her Miss Menten.Pittmed Magazine. 2000; 2: 18-21Google Scholar.1All the biographical information on Maud Menten was taken from Ref. 11Skloot R. Some called her Miss Menten.Pittmed Magazine. 2000; 2: 18-21Google Scholar. Michaelis left Berlin in 1922 when he was offered a professorship in biochemistry at the University of Nagoya in Japan. He remained in Japan until 1926 when he moved to America to be a resident lecturer at Johns Hopkins University. After three years at Johns Hopkins, Michaelis joined the Rockefeller Institute in New York. Michaelis' subsequent research in America focused mainly on oxidation-reduction processes, although he wasn't opposed to branching out into other areas as well. In 1939, Sam Granick (1909–1977), who had just earned his Ph.D. from the University of Michigan, joined Michaelis' laboratory to study iron metabolism. Between 1942 and 1946, Granick and Michaelis published a series of papers on ferritin and ferric compounds in the Journal of Biological Chemistry (JBC). The series, which was done in collaboration with Alexandre Rothen, not only formed the basis of our current knowledge of ferritin but also presented convincing evidence which contradicted previous beliefs about the structure and composition of the protein. The first and second papers in this series are reprinted here as JBC Classics. Prior to the publication of Granick and Michaelis' JBC series, Victor Laufberger had isolated a protein from horse spleen by crystallizing it as a cadmium salt (2Laufberger V. Sur la Cristallisation de la Ferritine.Bull. Soc. Chim. Biol. 1937; 19: 1575-1582Google Scholar). Because the protein contained over 20% iron by dry weight, he named it “ferritin” from the Latin “ferratus” or “bound with iron.” Several years later, Kuhn, Sorensen, and Birkofer published a paper in which they confirmed Laufberger's findings and concluded that ferritin consisted of 54.5% protein, 12.1% nucleic acid, and 35% Fe3+OH (3Kuhn R. Sorensen N.A. Birkofer L. Ber. Chem. Ges. 1940; 73B: 823Crossref Google Scholar). Because it worked out that there was an iron atom for every almost every peptide group, Kuhn, Sorensen, and Birkofer proposed that iron was incorporated into ferritin via bonds between single iron atoms and CONH groups. In the first paper in this set of JBC Classics, Granick describes the isolation of horse spleen ferritin by crystallization and reports on his characterization of the purified protein. Unlike Kuhn et al., Granick did not find evidence of nucleic acid in ferritin. He did, however, deduce that purified ferritin was inhomogeneous, based on ultracentrifugation and solubility experiments, as well as the observation that different crystallized ferritin samples contained different amounts of iron and phosphorus. Granick concluded that ferritin is “made up of brown particles having a molecular weight in the neighborhood of several million and grading down to colorless particles the size of large globulin molecules.” In the second paper reprinted here, Granick and Michaelis describe how they removed iron from ferritin to produce apoferritin. They did this by reducing the iron from the ferric to the ferrous state “in a solution not acid enough to denature the protein yet acid enough to be compatible with the existence of ferrous ions in solution.” Dialysis then produced a colorless protein which could be crystallized in the same conditions as ferritin. Granick and Michaelis' subsequent analysis of apoferritin unearthed two results which helped explain Granick's previous observations. First, the scientists discovered that apoferritin, unlike ferritin, is homogeneous. Second, they found that the only way to reinsert iron into apoferritin was by adding what they called “non-crystallizable ferritin” to a solution of apoferritin. This “non-crystallizable ferritin” was the iron-rich brown mother liquor that remained after ferritin was crystallized with cadmium sulfate. Importantly, they also found that “non-crystallizable ferritin” could not produce ferritin from apoferritin crystals, suggesting the iron was in a colloidal state that was not able to spontaneously diffuse into the crystals. Granick and Michaelis concluded that ferritin's iron does not occur as individual atoms attached to individual peptide groups but is instead present as micelles of colloidal iron that fill the interstices of the protein. This also explained why ferritin was non-homogeneous, the micelles could contain different amounts of iron as well as small amounts of phosphorus and nitrogen. In the remaining papers in the series (4Michaelis L. Coryell C.D. Granick S. Ferritin. III. The magnetic properties of ferritin and some other colloidal ferric compounds.J. Biol. Chem. 1943; 148: 463-480Abstract Full Text PDF Google Scholar, 5Granick S. Ferritin. IV. Occurrence and immunological properties of ferritin.J. Biol. Chem. 1943; 149: 157-167Abstract Full Text PDF Google Scholar, 6Fankuchen I. Ferritin. V. X-ray diffraction data on ferritin and apoferritin.J. Biol. Chem. 1943; 150: 57-59Abstract Full Text PDF Google Scholar, 7Hahn P.F. Granick S. Bale W.F. Michaelis L. Ferritin. VI. Conversion of inorganic and hemoglobin iron into ferritin iron in the animal body. Storage function of ferritin iron as shown by radioactive and magnetic measurements.J. Biol. Chem. 1943; 150: 407-412Abstract Full Text PDF Google Scholar, 8Greenberg D.M. Copp D.H. Cuthbertson E.M. Studies in mineral metabolism with the aid of artificial radioactive isotopes. VII. The distribution and excretion, particularly by way of the bile, of iron, cobalt, and manganese.J. Biol. Chem. 1943; 147: 749-756Abstract Full Text PDF Google Scholar, 9Granick S. Hahn P.F. Ferritin. VIII. Speed of uptake of iron by the liver and its conversion to ferritin iron.J. Biol. Chem. 1944; 155: 661-669Abstract Full Text PDF Google Scholar, 10Granick S. Ferritin. IX. Increase of the protein apoferritin in the gastrointestinal mucosa as a direct response to iron feeding. The function of ferritin in the regulation of iron absorption.J. Biol. Chem. 1946; 164: 737-746Abstract Full Text PDF PubMed Google Scholar), Granick, Michaelis, and others reported on subsequent discoveries such as the finding that ferritin occurs in a variety of organs in many animal species including humans and that it is used by the body to store iron in the Fe3+ state. Building on the groundwork laid by Granick and Michaelis, enormous amounts of research have added to the initial portrait of ferritin. We now know that ferritin is a 480,000-Da protein with a large cavity that can hold as many as 4,000 iron atoms as a solid oxo-mineral. Studies have also revealed that iron enters ferritin through pores in the protein where it is immediately oxidized and released into the interior of the protein. After publishing this series of JBC papers, Granick remained at Rockefeller where he worked on chloroplasts, chlorophyll biosynthesis, and iron metabolism until his death. In 1947, he and Keith R. Porter were the first to use an electron microscope to take pictures of chloroplasts, revealing dense grana and disk-like components. In recognition of his numerous contributions to science, Granick was elected to the National Academy of Sciences in 1965. 2All the biographical information on Sam Granick was taken from Ref. 12Bamberger W. Prof. Sam Granick, chlorophyll expert, found new protein.The New York Times. 1977; (May 3): 44Google Scholar.2All the biographical information on Sam Granick was taken from Ref. 12Bamberger W. Prof. Sam Granick, chlorophyll expert, found new protein.The New York Times. 1977; (May 3): 44Google Scholar. Michaelis remained at Rockefeller as well and kept up active research until his death. He was elected to the National Academy of Sciences in 1943 and became a Fellow of the New York Academy of Sciences and the American Association for the Advancement of Science. He also received the honorary degree of LL.D. from the University of California, Los Angeles, in 1945. 3All the biographical information on Leonor Michaelis was taken from Ref. 13Michaelis L Macinnes D.A. Granick S. Biographical memoir of Leonor Michaelis. 31. National Academy of Sciences, Washington D. C.1958: 282Google Scholar.3All the biographical information on Leonor Michaelis was taken from Ref. 13Michaelis L Macinnes D.A. Granick S. Biographical memoir of Leonor Michaelis. 31. National Academy of Sciences, Washington D. C.1958: 282Google Scholar.
Source: Journal of Biological Chemistry
Language: English
Subfield: History and Philosophy of Science
Field: Arts and Humanities
Domain: Social Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1578550478