title: The effect of proflavine on pyruvate kinase I of Escherichia coli B.
abstract: Proflavine (PF) inhibited glucose use in sensitive but not resistant Escherichia coli B. Glucose transport (as measured by alpha-methylglucoside accumulation) was only partly inhibited by PF concentration that completely blocked glucose use. Fructose 1,6-diphosphate-(FDP)-regulated pyruvate kinase (PK1) (EC 2.7.1.40), the only glycolytic enzyme affected by PF, was completely inhibited by a dye concentration of 0.8 mM. The inhibition curve for PF was sigmoidal, suggesting that PF was acting as an allosteric inhibitor. PF increased the K 1/2 for phosphoenolpyruvate (PEP) and lowered the V; however, it had no effect on the Hill number for PEP. PF inhibition was partially reversed by FDP but not by cyclic AMP, AMP, ATP, fuctose 6-phosphate, or dithiothreitol. Studies with a variety of acridines indicated that those substituted at the 3-position are the most effective inhibitors and also that hydrophobic interactions may be involved in PF inhibition of PK I. PK I for E. coli B/Pr was also strongly inhibited by PF, indicating that PF resistance does not lie at the level of this enzyme. Ribose-5-phosphate-regulated pyruvate kinase (EC 2.7.1.40) was much less sensitive that PK I to the inhibitory effects of PF. A role for PF as a molecular probe for PK I has been proposed.
mesh_terms: D000166:Acridines / Q000494:pharmacology*; D000494:Allosteric Regulation; D001692:Biological Transport; D002238:Carbohydrate Epimerases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000201:enzymology*; D005947:Glucose / Q000378:metabolism*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D008190:Lyases / Q000378:metabolism; D008757:Methylglucosides / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism; D011370:Proflavine / Q000494:pharmacology*; D011770:Pyruvate Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013045:Species Specificity
chemical_list: D000166:Acridines; D008757:Methylglucosides; D011370:Proflavine; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D010770:Phosphotransferases; D011770:Pyruvate Kinase; D008190:Lyases; D002238:Carbohydrate Epimerases; D005947:Glucose