Cellular mechanisms controlling rates of glucose consumption by yeast

Abstract

FOUR FIGURESUnder most circumstances, as will be illustrated snbsequently, the enzymatic equipment of each yeast cell operates at a rate which is far below capacity. The existence of a regulatory mechanism controlling the rate of glucose metabolisni has been the subject of extensive speculation in connection with the widely studied Pasteur eEect (see Lipmann, ,422). A key to the regulation of the rate of glucose metabolism in living yeast is seen in the suggestion by Meyerhof ('44) that in actively metabolizing yeast there is need for synchronization of phosphorplation and dephosphorylation since for each molecule of glucose fermented there is a net gain of approximately 2 high energy phosphate bonds. I n other words there is need for a balance between the rates of formation and dissipation of high energy phosphate bonds, Lipmann ('41). I n the presence of a non-limiting supply of inorganic phosphate in the medium, the adenylic acid system may become so engoiirged with phosphate that it can no longer serve a s a phosphate acceptor for fermentative dephosphorylations. This situation has been described by Meyerhof ( '45) as responsible for the slo-~v phase of cell-free fermentation. If, as Meyerhof assumes, the living cell has sufficient adenylpyrophosphatase for the regeneration of ATP, the synchronizing of phosphovylation and dephosphorylation rests upon outlets for high

The synthesis of glucuronides by liver slices

“…Inhibition by azide It has been known for some years that azide is able to prevent a variety of assimilatory and related processes. Although the original observations of Keilin (1937) that azide strongly inhibited both the respiration of yeast and the cytochrome oxidase system of heart might explain the effect under aerobic conditions, they are obviously insufficient to explain the influence upon anaerobic metabolism (Winzler, Burk & du Vigneaud, 1944;Brockmann & Stier, 1947;Spiegelman, Kamen & Sussman, 1948). It is now evident that, at concentrations which do not inhibit respiration, azide can still affect aerobic processes (Winzler, 1940;Hotchkiss, 1944;Giese, 1945;Clifton, 1946).…”