The putative electrogenic nitrate-proton symport of the yeast Candida utilis. Comparison with the systems absorbing glucose or lactate.
Strain N.C.Y.C. 193 of Candida utilis was grown aerobically at 30 degrees C with nitrate as limiting nutrient in a chemostat. The washed yeast cells depleted of ATP absorbed up to 5 nmol of nitrate/mg dry wt. of yeast. At pH 4-6, extra protons and nitrate entered the yeast cells together, in a ratio of about 2:1. Charge balance was maintained by an outflow of about 1 equiv. of K+. Nitrate stimulated the uptake of about 1 proton equivalent during glycolysis or aerobic energy metabolism. Studies with 3,3'-dipropylthiadicarbocyanine indicated that the proton-linked absorption of nitrate, amino acids or glucose depolarized the yeast cells. Proton uptake along with lactate led neither to net expulsion of K+ nor to membrane depolarization.
D000042:Absorption; D052160:Benzothiazoles; D001693:Biological Transport, Active; D002175:Candida / Q000378:metabolism*; D002232:Carbocyanines; D005456:Fluorescent Dyes; D005947:Glucose / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008320:Maltose / Q000494:pharmacology; D008564:Membrane Potentials; D009566:Nitrates / Q000378:metabolism*; D011522:Protons; D013050:Spectrometry, Fluorescence
D052160:Benzothiazoles; D002232:Carbocyanines; D005456:Fluorescent Dyes; D007773:Lactates; D009566:Nitrates; D011522:Protons; D019344:Lactic Acid; C012944:3,3'-dipropyl-2,2'-thiadicarbocyanine; D008320:Maltose; D005947:Glucose