The effect of glucose on chloride uptake by Chlorella |
| |
Authors: | R Doblinger H W Tromballa |
| |
Institution: | (1) Institut für Physikalische Chemie der Universität, Währingerstrasse 42, A-1090 Wien, Austria |
| |
Abstract: | Active Cl- uptake by Chlorella fusca was examined by using 36Cl as a label. Under light/air conditions chloride influx from a 2.4·10-5 M solution was 4.0±0.04 nmol m-2s-1. After 70±10 min a stationary 380±40 fold accumulation was reached. In dark/air and dark/argon influx and accumulation were reduced to 25±6%, respectively, 5±1.5% of the light/air control. Cl- uptake had a broad optimum around pH 7 and showed saturation kinetics with a K
M of 1.25·10-5 M and a v
max of 7.0 nmol m-2s-1 in light/air. Br- inhibited Cl- uptake strongly, J-, ClO
4
-
, SO
4
2-
, and NO
3
-
had no inhibitory effect. Inhibitor studies with carbonyl cyanide m-chlorophenylhydrazone and N,N -dicyclohexylcarbodiimide resulted in a good correlation between Cl- uptake and ATP level. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea and darkness reduced transport activity without affecting the ATP level.The magnitudes of the pH gradient and the membrane potential across the cell membrane were determined and/or estimated under different conditions. It could be shown that in Chlorella Cl- transport cannot proceed via secondary active H+/Cl- cotransport. In addition, 2H+/Cl- cotransport seems unlikely for energetic reasons. On the basis of the results of this and the following study, a primary active ATP-driven Cl-/OH- exchange pump is proposed.Abbreviations CCCP
carbonyl cyanide m-chlorophenylhyd razone
- DCCD
N,N -dicyclohexylcarbodiimide
- DCMU
3-(3.4-dichlorophenyl)-1.1-dimethylurea
- DMO
5,5-dimethyloxazolidine-2,4-dione
- Hepes
N-2-hydroxyethylpiperazine-N ethane-sulfonic acid
- POPOP
1.4-bis-2-(4-methyl-5-phenyloxazolyl)-benzene
- PPO
2.5-diphenyloxazole
To whom correspondence should be addressed |
| |
Keywords: | ATP level Chlorella Chloride transport Intracellular pH Membrane potential |
本文献已被 SpringerLink 等数据库收录! |
|