Carrier-Mediated Transport of Folate in a Mutant of Pediococcus cerevisiae
AUTOR(ES)
Shavit, Frederika Mandelbaum
RESUMO
A mutant strain of Pediococcus cerevisiae (P. cerevisiae/PteGlu) was isolated which grows on low-folate (PteGlu) concentrations (200 pg/ml). The growth response of the parent and mutant strains to folinate (5-CHO-H4PteGlu) was the same. The transport of 14C-PteGlu by P. cerevisiae/PteGlu was temperature-dependent (Q10 between 27 C and 37 C was about 2), energy-dependent, and pH-dependent and was inhibited by iodoacetate, 2,4-dinitrophenol, potassium fluoride, and sodium azide. The uptake obeyed saturation kinetics with an apparent Km of 6.6 × 10−6 M and Vmax of 4.0 × 10−10 mol per min per mg (dry weight). At the steady state the intracellular concentration of PteGlu was 120-fold higher from that of the medium. Reduced folates like 5-CHO-H4PteGlu and methyl-tetrahydrofolate (5-CH3-H4PteGlu) as well as 2,4-diaminoanalogues (amethopterin and aminopterin) were shown to compete for the PteGlue-carrier.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=251800Documentos Relacionados
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