In vitro effect of n-hexane and its metabolites on selected enzymes in glycolysis, pentose phosphate pathway and citric acid cycle.

The effect of n-hexane, 2-hexanol, 5-hydroxy-2-hexanone, 2,5-hexanediol, methyl n-butyl ketone ( MnBK ) and 2,5-hexanedione (2,5-HD) has been studied in vitro on crystalline glyceraldehyde-3-phosphate dehydrogenase (GAPDH), DL-glyceraldehyde-3-phosphate: NAD oxidoreductase (phosphorylating) EC. 1.2.1.12 and phosphofructokinase (PFK) ATP: D-fructose-6-phosphate-1-phosphotransferase; EC. 2.7.1.11 and lactic dehydrogenase (LDH) L-lactate: NAD+ oxidoreductase, EC. 1.1.1.27. MnBK and 2,5-HD both inhibited GAPDH and PFK activities selectively. n-Hexane and 2-hexanol had no effect on GAPDH and PFK activities; 5-hydroxy-2-hexanone and 2,5-hexanediol exhibited a slight inhibitory effect on these enzymes. Neither metabolites of n-hexane have any effect on LDH activity. 2,5-Hexanedione did not inhibit transketolase (D-sedoheptulose-7-phosphate: D-glyceraldehyde-3-phosphate glycolaldehyde transferase, EC. 2.2.1.1) and succinate dehydrogenase (succinate: 2,6-dichlorophenol-indophenol oxidoreductase, EC. 1.3.99.1) activities. The levels of ATP were reduced in 2,5-HD-treated cat sciatic nerves and returned to normal levels by exposing the nerve to sodium pyruvate.