Hassid cited for work in carbohydrates For his outstanding contributions to carbohydrate chemistry, Dr. William Z. Hassid, professor emeritus of biochemistry at University of California, Berkeley, and biochemist at the university's agricultural experiment station, has received the 1967 Claude S. Hudson Award of the ACS Division
of Carbohydrate Chemistry. Presentation of the award was made during the Society's 154th National Meeting in Chicago. The award was granted for Dr. Hassid's pioneering efforts in enzymic synthesis of sucrose, lactose, pectin, and xylan, the biosynthesis of cellulose, his elucidation of the structure of starch, the concept of transglycosidation, and the discovery of biosynthetic carbohydrate intermediates and enzymes. Born in 1897 in Jaffa, Palestine, Dr. Hassid came to the U.S. in 1920 and became a naturalized citizen six years later. He received his A.B. from the University of California in 1925 and was a research assistant there during the years of his graduate studies. He received his M.S. in 1930 and his Ph.D. in 1934. He was promoted to professor in 1947 and served in this capacity until he retired in 1965. Dr. Hassid's work has dealt primarily with isolation of various carbohydrates from plants, and determination of their chemical configurations and modes of formation. He contributed to knowledge of the structure of starch and the enzymic mechanisms involved in its synthesis and degradation. He also elucidated the structure of synthetic polysaccharides produced by plant and animal phosphorylases and their relation to the natural starches. In 1944 he accomplished (with M. Doudorff and H. A. Barker) the first enzymic synthesis of sucrose. Several
new analogs of sucrose were then synthesized with the same enzyme. From this work emerged the important concept of transglycosidation, which explains the formation of many naturally occurring complex saccharides from disaccharides in the absence of inorganic phosphate. Dr. Hassid, working with a team of associates, isolated a number of sugar nucleotides, important carbohydrate intermediates, from plants. Pyrophosphorylases capable of producing these uridine diphosphate intermediates were isolated from mung beans and various other plants. Other enzymes, epimerases, were discovered. These cause inter con version of the various sugar nucleotides. Thus, the uridine derivatives of D-glucose and D-galactose, D-glucuronic acid and D-galacturonic acid, and D-xylose and L-arabinose are converted into one another by these enzymes. An important enzyme, capable of decarboxylating uridine diphosphate D-glucuronic acid to uridine diphosphate D-xylose, was also discovered in his laboratory to be present in plants. When the latter pentose diphosphate nucleotide forms, it is partially converted to uridine diphosphate L-arabinose. These different enzymes account for the formation of various sugars in the free or combined form in plants. Sugar nucleotides containing bases other than uracil were also discovered in plants. Thus, a guanosine diphosphate D-mannose and the enzyme which synthesizes it were discovered in certain marine algae. The various sugar nucleotides which are enzymically formed in plants were found by Dr. Hassid and his associates to be the precursors of the principal cell-wall polysaccharides, such as cellulose, xylan, glucomannan, the polygalacturonic acid of pectin, and callose, and of the complex metabolic carbohydrates such as raffmose and certain glycosides. Dr. Hassid was chairman of the ACS Division of Carbohydrate Chemistry, 1949-50. He also belongs to the Chemical Society (London), American Society of Biological Chemists, Biochemical Society, and American Society of Plant Physiologists. He received the Sugar Foundation Award in 1946 and was a Guggenheim fellow in 1955 and 1962. He is author or coauthor of more than 160 papers. He was a member of the editorial boards of Annual Review of Biochemistry (1954-59) and Journal of Biological Chemistry (1961-66). He has served on the advisory boards of Carbohydrate Research and Photochemistry.
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