Vmax and Km of glucose transport and specific growth rates

Range Table - link
Organism Budding yeast Saccharomyces cerevisiae
Reference Karin Elbing, Christer Larsson, Roslyn M Bill, Eva Albers, Jacky L Snoep, Eckhard Boles, Stefan Hohmann, and Lena Gustafsson. Role of hexose transport in control of glycolytic flux in Saccharomyces cerevisiae. Appl. Environ. Microbiol., 70(9):5323–5330, 2004 p.5327 table 2PubMed ID15345416
Method P.5328 left column bottom paragraph: "[Researchers] have constructed functional chimeras between the low and high-affinity transporters Hxt1 and Hxt7 in order to further understand how changes in glucose uptake affect yeast metabolism. [Their] series of strains displayed different rates of ethanol production, which correlated linearly with the maximal specific glucose consumption rates attained during exponential growth on glucose (Fig. 3). Hence, restricted glucose consumption, and consequently a reduced glycolytic rate, is a strong candidate for explaining the observed differences in ethanol yield. Restricted glucose consumption, in turn, is explained by different capacities of the glucose transporters. Indeed, the strains with the highest glucose uptake capacity (Vmax [Table 2], Vapp [Fig. 4]) showed the highest glucose consumption and ethanol production rates, and vice versa."
Comments P.5326 right column 3rd paragraph: "Glucose transport in the different strains exhibited low (Km, 50 to 250 mM)- or medium- to high (Km, ca. 2 to 10 mM)-affinity kinetics (Table 2). The differences in gas profiles (Fig. 1) correlated with the kinetic differences of the chimeric glucose transporters (Table 2)." P.5327 left column bottom paragraph: "The use of [researchers'] strains with altered glucose transport capacity offers the possibility to study the control of glycolytic flux by glucose uptake. By using log-log plots according to the theory of metabolic control analysis, it is possible to determine to what extent an enzymatic step controls the steady-state rate of a pathway (refs 13, 20, 22). However, neither Vmax nor Vapp (Fig. 4) activities of the chimeric transporters can be used directly in an estimation of the control of glucose transport in wild-type S. cerevisiae. This is because the transporters not only have different Vmax values but also have different affinities (Km) for glucose (see table 2)." See notes beneath table
Entered by Uri M
ID 110954