title: Enzymatic determination of pyrroloquinoline quinone using crude membranes from Escherichia coli.
abstract: Escherichia coli K-12 (ATCC 10 798) contains only the apoform of membrane-bound D-glucose dehydrogenase (pyrroloquinoline quinone-dependent). Crude membrane preparations or even crude cell extracts are suitable for a sensitive determination of pyrroloquinoline quinone under appropriate conditions. The apoform of D-glucose dehydrogenase from E. coli is reconstituted with pyrroloquinoline quinone to the holoenzyme in the presence of Mg2+ and assayed for glucose dehydrogenase activity. By increasing the time of reconstitution it is possible to detect minute amounts of about 20 pg pyrroloquinoline quinone.
mesh_terms: D001051:Apoenzymes; D002237:Carbohydrate Dehydrogenases; D004492:Edetic Acid; D004926:Escherichia coli / Q000201:enzymology*; D005069:Evaluation Studies as Topic; D042843:Glucose 1-Dehydrogenase; D005948:Glucose Dehydrogenases; D008566:Membranes / Q000201:enzymology; D045542:PQQ Cofactor; D011804:Quinolines / Q000032:analysis*
chemical_list: D001051:Apoenzymes; D011804:Quinolines; D045542:PQQ Cofactor; D004492:Edetic Acid; D002237:Carbohydrate Dehydrogenases; D005948:Glucose Dehydrogenases; D042843:Glucose 1-Dehydrogenase