Resistance to Pediococcus cerevisiae to amethopterin as a consequence of changes in enzymatic activity and cell permeability. II. Permeability changes to amethopterin and other folates in the drug-resistant mutant.

@article{MandelbaumShavit1976ResistanceTP,
  title={Resistance to Pediococcus cerevisiae to amethopterin as a consequence of changes in enzymatic activity and cell permeability. II. Permeability changes to amethopterin and other folates in the drug-resistant mutant.},
  author={F. Mandelbaum-Shavit},
  journal={Biochimica et biophysica acta},
  year={1976},
  volume={428 3},
  pages={
          674-82
        }
}
the accumulation of amethopterin in a Pediococcus cerevisiae strain resistant to this analogue was about 30% of that in P. cerevisiae/PteGlu, the sensitive parent. The uptake in the resistant strain was strictly glucose dependent, whereas in the sensitive parent about 16% accumulation occurred in absence of glucose. The transport in both strains was inhibited by iodoacetate and KF. Amethopterin uptake exhibited saturation kinetics with an apparent Km of 5 muM in P. cerevisiae/AMr and 0.5 muM in… Expand
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References

SHOWING 1-8 OF 8 REFERENCES
Pediococcus cerevisiae mutant with altered transport of folates
A Pediococcus cerevisiae mutant that actively accumulated folate (PteGlu), in contrast to the wild-type, was also found to exhibit changes in the pattern of uptake of 5-methyl-tetrahydrofolateExpand
Genetically Alterable Transport of Amethopterin in Diplococcus pneumoniae II. Impairment of the System Associated with Various Mutant Genotypes
TLDR
Six mutations determining resistance to amethopterin were examined for their effects on the active transport of the drug andKinetic analysis of transport showed an increase in the value for K(m) of the system in all of the mutants. Expand
Effect of Folinate on Thymidine Uptake by Pediococcus cerevisiae
TLDR
The folinate effect was due to stimulation of de novo thymidylate synthesis with concomitant inhibition of the uptake of external thymidine, and cells preincubated with folinate showed an increased incorporation of (14)C-uracil into DNA, presumably after prior conversion to thymIDylate. Expand
On the nature of a transport alteration determining resistance to amethopterin in the L1210 leukemia.
TLDR
Kinetic analysis revealed an increase in the Michaelis constant for the system in these resistant cells, suggesting an alteration in the binding properties of a carrier component as the basis for the impairment. Expand
COMPARATIVE BIOCHEMISTRY OF DIHYDROFOLATE REDUCTASE
  • J. Burchall
  • Chemistry, Medicine
  • Annals of the New York Academy of Sciences
  • 1971
TLDR
Enzyme binding, rather than transport, nonspecific binding, or degradative reactions, appears to be the major factor in determining the activity of these inhibitors against whole cells. Expand
Dihydrofolate reductases from the wild type and aminopterin-resistant mutants of Diplococcus pneumoniae
TLDR
Dihydrofolate reductase from the wild type and aminopterin-resistant mutants of Diplococcus pneumoniae has been compared and it is found that Aminopterin resistance for such mutants is, therefore, not due to an alteration of the dihydrofolates reduct enzyme. Expand
A simple method for the preparation of 5-methyltetrahydropteroylglutamic acid.
Acidification of 5-formyltetrahydropteroylglutamic acid, followed by reduction at pH7.0, provided a simple method of preparing 5-methyltetrahydropteroylglutamic acid.