Effects of the Fenton reagent on transport in yeast.
In the facultatively anaerobic yeast Saccharomyces cerevisiae the uptake rate and the accumulation ratio of 2-aminoisobutyric acid was decreased by some 30% by Fenton's reagent (FR), a powerful source of OH. radicals. Likewise, the uptake of glutamic acid, leucine and arginine was diminished. The mediated diffusion of 6-deoxy-D-glucose was not affected. The H+ symport of maltose and trehalose was inhibited by some 40% both in the initial rate and in the accumulation ratio. FR had a dramatic inhibitory effect when present during preincubation with 50 mmol/L glucose. In the obligately aerobic Lodderomyces elongisporus the uptake of all amino acids tested was decreased by 15-30%, that of 6-deoxy-D-glucose by about 10%. The initial rates of uptake of maltose and trehalose were depressed by FR by 40% and the acceleration of uptake observed after 8 min of incubation, was abolished by FR completely. Acidification rate of the external medium by S. cerevisiae in the presence of glucose or galactose was enhanced three-fold, that after subsequently added K+ was substantially decreased. FR appears to have a dual effect on sugar and amino acid transport processes in yeast: (1) it blocks carrier protein synthesis; (2) it inhibits the source of energy for transport. It does not appreciably affect the carrier proteins themselves.
Khansuwan
U
U
Department of Biochemistry, Faculty of Medicine, University of Chiang Mai, Chiang Mai 50200, Thailand.
Kotyk
A
A
D000596:Amino Acids / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D050260:Carbohydrate Metabolism; D002352:Carrier Proteins / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000494:pharmacology*; D007700:Kinetics; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000378:metabolism*; D004718:Saccharomycetales / Q000187:drug effects* / Q000378:metabolism*
D000596:Amino Acids; D002352:Carrier Proteins; C045076:Fenton's reagent; D005656:Fungal Proteins; D006861:Hydrogen Peroxide; D007501:Iron