Epoxides as reactive intermediates in aromatic hydrocarbon metabolism.

shown by demonstrating that the overall rate of dextransucrase synthesis is independent of the concentration of 1,6-linked dextran acceptor if synthesis is continued for periods that are directly proportional to the amount of acceptor present. For example, in the presence of 1 mg of acceptor dextran, the rate of dextransucrase action measured over lOmin is identical with the rate measured over 20min in the presence of 2mg of acceptor dextran. The analogy of the dextran system to the extension of glycogen chains by phosphorylase and synthetase is apparent. One difference is that synthesis decreases the acceptor efficiency of glycogen, whereas the dextran acceptor efficiency increases as the reaction proceeds. In both cases, however, the intrinsic rates of the synthesizing enzymes are independent of the concentration of macromolecular acceptors. The importance of the 1,6-a-glucosidic linkage to the structure and synthesis of glycogen need not be emphasized. The dextran reaction described here also may be important in vivo for the production of increased amounts of insoluble dextran. A relationship is also seen between the water solubility and the 1,6-glucosidiclinkage content of S. mutans dextran fractions. Their solubility increases as the content of 1 ,64nkages increase (Meyer et al., 1974). It remains to be established whether the 1,Qlinkages in these fractions are an integral feature of the dextran structure, or whether they reflect the presence of a 1,dlinked dextran backbone which served as an acceptor as in the system described here.