Cori Receives Gibbs Medal Λ
STAFF
Roger Adams, 1936 Gibbs Medalist, presents the Willard Gibbs Medal to Carl F . Cori oj Wash ington University in recognition €>f*6his eminent work and origi nal contributions" to chemistry
A N recognition of "his eminent work and original contributions" to chemistry, Carl F. Cori of Washington University was awarded the 1948 Willard Gibbs Medal, by the Chicago Section of t h e AMERICAN CHEMICAL SOCIETY, May
21.
According to a more detailed citation, the medal was awarded to Dr. Cori " . . . in recognition of his m a n y fundamental contributions to the chemistry of car bohydrate metabolism—notably his dis covery of glucose- 1-phosphate (the Cori ester), his isolation of crystalline muscle phosphorylase and the elucidation of the role played by these substances in the en zymatic synthesis of glycogen ; his studies on the regulatory effects of the pituitary, pancreatic, and adrenal cortex hormones on glucose utilization; and his investiga tions concerning the energetics of carbo hydrate transformations." Edward Doisy, St. Louis University, former Gibbs medalist, paid personal trib ute to.Dr. Cori, who with his wife Gerty T . Cori, also a professor a t Washington Uni versity, received the Nobel prize for deter mining the process by which the body stores sugar in the liver as glycogen, then recon verts to sugar as it is needed. Dr. Doisy related that I IK» (Oris came to the United States from Austria in 1922, to work first, for the New York State Institute for the Study of Malignant Diseases, where they worked on the cancer problem. In 1931 they moved to Washington University. In addition to Dr. Cori\s work on the reversible metabolic process for conversion of glucose to glycogen, and the isolation of the enzyme phosphorylase in crystalline form, which Dr. Doisy mentioned as his greatest contribution, the latter mentioned as major accomplishments b y Dr. Cori, in collaboration with his wife, the research in hexokinase, studies of insulin action, hormone investigations, and the relation-
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ship of enzymatic action to hormonal ac tion. Dr. Doisy cited among the honors be stowed upon Dr. Carl or both of the Coris, in addition to the Nobel prize, the Midwest Award, the Squibb Award, a Lasker Award ; and a $5,000 award from the N a tional Science Fund of the National Acad emy of Science. Roger Adams, University of Illinois, in making the presentation of the Gibbs Medal to Dr. Cori said, "The medalist's work from the beginning of his career has been characterized b y reliability, meticu lous care, precision, exact observation, and keen interpretation of results. His is t h e ingenuity and philosophical reasoning of a genius. He has avoided the pitfalls which arc sometimes encountered by many scien tists: the use of untested assumptions, t h e drawing of unwarranted conclusions from experimental facts, and the neglect of d e tails. He is a scholar whoso greatest d e sire is still to be in the laboratory. "The accomplishments in research are not the only qualifications to be mentioned in a citation of Dr. Cori. Modest, unpre tentious, unaffected by his many honors, eager t o help his fellow cliemists, both young and old, he is an inspiration to all scientists." Tn accepting the Willard Gibbs Medal, Dr. Cori was the thirt\'-sevciith t o join the
REPORT
group of recipients, leading scientists of the world, who have been given the award established by William A. Converse, chair man of the Chicago Section in 1910. The history of the medal was discussed briefly by Η. Ε. Robinson, Swift and Co., present chairman of the Chicago Section, who pre sented a moment ο of the occasion to Earl M. Converse, brother of the medal's originator. In his medal address, Dr. Cori discussed "The Enzymatic Synthesis and Degrada tion of Polysaccharides." Beginning with a description of the degradation of a starch by amylase, he showed that it was found that the degradation of glycogen is different. This was indicated by an ex periment with cell-free, dialyzed liver ex tract in which there was no degradation of glycogen unless inorganic phosphate was added and which gave glucose and glucose6-phosphate in the presence of the phos phate. The enzyme which acts exclusively in the presence of phosphate is called phos phorylase because it splits the glucosidic bonds of glycogen, not by the introduction of the elements of water, as with the amyl ases, but by the introduction of the phos phate group. It was also found, Dr. Cori related, that there is actually another compound formed before the glucose-6-phosphate, and this is rapidly converted t o the 6-phosphate. The reversible reaction to form glucose-1phosphate from glycogen and phosphate in the presence of phosphorylase was found to be in equilibrium at pH 7 and 30° C : 23% glycogen -f- PO"*^Z^.glucose- l-phosphate 77%
Conrad Elvehjem, University of Wisconsin, Gibbs medalist, 1943; Gerty T. tvife and co-worker of the 1948 medalist: and Eflwaril A. Doisy, St. Louis versity, 1941 Gibbs medalist, who, like Dr. Cori, also won a Nobel
CHEMICAL
AND
ENGINEERING
Cari, Uni prise
NEWS
Chicago ACS Section, verse, ivho originally with II. E. Robinson
Ε. Η. Volwiler, Abbott Laboratories, and University of Chicago* Gibbs medalist, medalist. Charles Kaxvin, retired, early
II". D. Harkins, 1928, with the member of the
The subsequent conversion to the G-phosphate is much faster, the latter being fa vored to the extent of 9 5 % in the equilib rium. This reaction is promoted by the enzyme phosphoglucomutase. In order to study the glucose-1-phosphate more satisfactorily, i t was synthesized by the treatment of acetobromoglucose with trisilver phosphate in dry benzene to yield tri-(tetraacetyl glucose-1 )-phosphate which was hydrolyzed to the desired product. In the isolation of phosphorylase it was found that it is acted upon by an enzyme in tissue extracts which removes its pros thetic group. Thus there are phosphorylases, called A and B, the latter being inac tive unless adenylic acid is added and also very difficult to crystallize. It was essen tial to remove the prosthetic-group remov ing enzyme to prepare crystalline phos phorylase. Furthermore, it was found es sential to have cysteine present as a re ducing agent. Phosphorylase was se cured in crystalline form, however, and found to have a molecular weight of 400,000. Dr. Cori reported that, at 3 0 ° C. and pH 7, one molecule of the enzyme de
composes 40,000 glucose-l-phosphate mole cules per minute. The synthesis of polysaccharides by phosphorylase was discussed. It was found that phosphorylase is not self-start ing with glucose-1-phosphate as substrate, but needs the presence of some glycogen or starch as a primer of the synthetic reaction. Crystalline muscle phosphorylase was shown to form a polysaccharide giving an intense blue color with iodine. The poly saccharide is poorly soluble in cold water and more soluble in bot water or alkali. I t precipitates therefrom on cooling or neu tralization with the precipitated material giving a characteristic x-ray pattern. It has a chain length of about 200 glucose units and is completely digested by fl amy lase. Thus it resembles the linear or amylose fraction of natural starch and dif fers sharply from the branched polysac charides such as glycogen or amylopectin. Dr. Cori dealt with the theory of the action of phosphorylase. It is assumed, since the addition of a polysaccharide as a reactant is required before a new poly saccharide can be formed, that it builds
F. H. Lee, Nanking
University,
with
Dr. and Mrs. L. M.
Hendersan
and close *tssociate of William Con endowed the Willarri Gibbs Medal, chairman of the Chicago Section y
o n t o existing polysaccharide chains, which a r e thereby made longer. T h e length of t h e newly formed chains, he said, has been s h o w n to be determined by the ratio of a d d e d primer end groups to the amount of glucose-1-phosphate which has reacted. T h i s theory explains the observation that t h e equilibrium of the reaction is independ e n t of the concentration of polysaccharide, which follows from the fact that the con centration of terminal glucose units re mains constant whether chain units are a d d e d or taken away. T h e process is sum marized : Terminal glucose (of η chain units) 4glucose-1 -phosphate «=* tormina! glucose (of η 4- 1 chain units) -+phosphate Κ =
[phosphate] [glucose-1-phosphate]
In contrast to the synthesis of linear polysaccharides, Dr. Cori showed that the synthesis of branched chain polysacchar ides requires the combined action of two enzymes. In discussing the energy considerations involved in the glucose to glycogen syn thesis, D r . Cori showed the series of re actions: glucose -+- adenosine tri phosphate —• glucose-6-phosphate —*> glucose-1-phosphate —* glycogen This, he said, takes place in the body when there is a supply of sugar available t o the body beyond its needs. It is the first re action of this series which requires energy, t h e so-called hexokinase reaction, in which a phosphate group is transferred from adenosine tri phosphate to glucose. This reaction is irreversible and its continued occurrence is dependent on (he regenera tion of adenosine triphosphate from inor ganic phosphate by energy supplied from oxidations. Dr. Cori stated that the rate o f hexokinase reaction in the muscle of the intact an»mal is controlled by hormones from the pancreas, anterior pituitary, and adrenal cortex.
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JUNE
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1948
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