title: Application of a quick, simple and direct radiometric assay for 4-aminobutyrate:2-oxoglutarate aminotransferase to studies of the parasitic nematode Nippostrongylus brasiliensis.
abstract: A preparation of rat brain was used to develop a quick and simple radiometric assay for 4-aminobutyrate: 2-oxoglutarate aminotransferase (GABA-T), an important enzyme in neural tissue of vertebrates and invertebrates. Application of the methodology to the parasitic nematode Nippostrongylus brasiliensis revealed that a soluble preparation of partially purified GABA-T could be recovered in high yield. This enzyme had a specific activity comparable to that observed in rat brain after similar treatment, was very stable when frozen, depended for activity upon tightly-bound pyridoxal 5-phosphate, had an apparent molecular weight of 72,000 and was strongly inhibited by NaCl. The inhibition was competitive with 4-aminobutyrate (Ki = 20 mM) but uncompetitive with 2-oxoglutarate (Ki = 160 mM).
mesh_terms: D000612:4-Aminobutyrate Transaminase / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D002250:Carbon Radioisotopes; D002411:Cation Exchange Resins; D004355:Drug Stability; D008722:Methods; D009559:Nippostrongylus / Q000201:enzymology*; D011732:Pyridoxal Phosphate / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002250:Carbon Radioisotopes; D002411:Cation Exchange Resins; D011732:Pyridoxal Phosphate; D000612:4-Aminobutyrate Transaminase