sodium-perchlorate and chlorite

Chlorite dismutase (CD) catalyzes the disproportionation of chlorite to chloride (ClO(2)(-)-->Cl(-)+O(2)) and is present in bacteria capable of cell respiration using perchlorate or chlorate. The activity of this enzyme has previously been measured by monitoring oxygen evolution using a Clark-type dissolved oxygen (DO) probe. We demonstrate here, using two other methods to measure CD activity (a chloride-specific electrode and ion chromatography (IC)) via chloride production, that the DO probe method underestimates dismutation rates. Of the three methods, the chloride probe was the easiest to use and did not require extensive sample handling or post-experimental analysis. Using the chloride electrode method, we determined whole cell rate constants (V(max)=64 U/mg DW, K(m)=0.17 mM) for the chlorate-grown suspensions of Dechlorosoma sp. strain KJ. We compared the CD activities of strain KJ at a fixed chlorite concentration (0.6 mM) to four other perchlorate respiring bacteria (PRB), and to one non-PRB (Pseudomonas aeruginosa). Chlorate-grown cultures of the five PRB strains had CD activities ranging from 25 to 50 U/mg of cell dry weight (DW), while aerobically grown cultures of the PRB had much lower CD activities (0.5-4 U/mg DW). To our knowledge, this is the first systematic comparison of the different methods to measure CD activities, and the first comparison of CD activities of different PRBs.

Topics: Aerobiosis; Anaerobiosis; Bacteria; Chlorides; Chromatography, Ion Exchange; Dose-Response Relationship, Drug; Electrodes; Hydrogen-Ion Concentration; Kinetics; Oxidoreductases; Oxygen; Perchlorates; Proteobacteria; Pseudomonas aeruginosa; Sodium Compounds

The abilities of sodium hypochlorite (NaClO), chlorite (NaClO2), chlorate (NaClO3), and perchlorate (NaClO4) to initiate lipid peroxidation (LP) in liposomes formed from unsaturated phosphatidylcholine were compared. It was shown that only NaClO induced an intensive accumulation of LP products (thiobarbituric acid-reactive substances and diene conjugates) in the liposomes as a result of their co-incubation. The other oxochlorates produced no similar effects and did not affect the hypochlorite-induced LP. This indicates that the observed hypochlorite-induced LP does not result from the presence of chlorite, chlorate, or perchlorate anion admixtures in the medium.

Topics: Animals; Chickens; Chlorides; Hypochlorous Acid; Lipid Peroxidation; Liposomes; Perchlorates; Phospholipids; Sodium Chloride; Sodium Compounds; Spectrophotometry; Thiobarbituric Acid Reactive Substances