The mechanism of polysaccharide production from sucrose.

The recent preparation of levansucrase, like that of dextransucrase and phosphorylase, brings a new and powerful tool to bear on the study of macromolecular biosynthesis (Hestrin, Avineri-Shapiro & Aschner, 1943; Hestrin & Avineri-Shapiro, 1943; Hehre & Sugg, 1942; Stacey, 1942, 1943; cf. also Cori, 1939; Hanes, 1940; Behrens & Bergmann, 1939). Recent work on polysaccharide production in vitro has largely been dominated by the discoveries of the Cori school concerning the central role of phosphorylase and phosphate in the biological breakdown and formation of glycogen and starch. The experiments reported below describe the reaction balance-sheet, the substrate requirement, and the inhibitors and activators of a levan-forming enzyme system. Inorganic phosphate does not appear to be necessary for levan production. This strengthens the view that phosphorylation is but one of several processes used by living cells for the synthesis of macromolecules of the polysaccharide class. The reactions leading to levan and dextran production may have implications in the field of oligase specificity (Harrison, Taxr & Hibbert, 1930; Norman, 1937; Hehre, 1941; Hestrin & AvineriShapiro, 1943), and in the development of cell properties such as virulence, resistance, and antigenicity, known to be conditioned by the dextranand levan-containing bacterial capsule (Beijerinck, 1912; Heidelberger, 1927; Evans, Hawkins & Hibbert, 1941; Hehre & Sugg, 1942). Moreover, levan and dextran occur not only in many bacteria but also in several fungi (Kopeloff, Welcome & Kopeloff, 1920; Anderson & Raistrick, 1936) and in a variety of green plants (Hibbert, Tipson & Brauns, 1931; Challinor, Haworth & Hirst, 1934; Hassid, 1939); and it is thus possible that the mechanism of polysaccharide production from sucrose, exemplified by the Aerobacter levanicum levansucrase used in the present investigation, is of widespread occurrence throughout microbe and plant life. METHODS