Relationship between sugar structure and competition for the sugar transport system in Bakers' yeast.
Twenty-five sugars have been compared as inhibitors of l-sorbose or d-xylose transport by the constitutive, monosaccharide transport system in bakers' yeast. d-Glucose showed the highest activity (i.e., apparent K(i) = 5 mm). Since all sugars except 2-deoxyglucose showed a decrease in activity relative to glucose (i.e., apparent K(i) = 25 - >2,000 mm), an attempt was made to relate the activity of each sugar with the way its structure differs from that of d-glucose. Assuming that the inhibition was the result of sugar-carrier complex formation, the analysis showed that the transport system has a rather broad specificity for pyranoses. Single changes at each of the five carbons of d-glucose (except for the 2-deoxy derivative) result in variable decreases in activity depending upon the carbon number and the alteration. The largest decrease in activity effected by a single change is the methylation or glucosylation of the anomeric hydroxyl. The combination of two or more changes leads to a decrease which is greater than the decrease in activity resulting from the individual changes occurring alone.
D001089:Arabinose / Q000378:metabolism; D001692:Biological Transport; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005632:Fructose / Q000378:metabolism; D005643:Fucose / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006027:Glycosides / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D009005:Monosaccharides / Q000378:metabolism*; D012210:Rhamnose / Q000378:metabolism; D012266:Ribose / Q000378:metabolism; D012440:Saccharomyces / Q000378:metabolism*; D013013:Sorbose / Q000378:metabolism; D014994:Xylose / Q000378:metabolism
D006027:Glycosides; D009005:Monosaccharides; D005643:Fucose; D005632:Fructose; D012266:Ribose; D014994:Xylose; D001089:Arabinose; D005947:Glucose; D013013:Sorbose; D008358:Mannose; D012210:Rhamnose; D005690:Galactose