title: Gamma-aminobutric acid and glutamate decarboxylas (l-glutamate 1-carboxy-lyase e.c. 4.1.1.15) in the nervous system of the cockroach, periplaneta americana.i.regional distribution and properties of the enzyme.
abstract: Both the central and peripheral nervous system of the cockroach Periplaneta americana contain gamma-aminobutyric acid (GABA) and glutamate decarboxylase (GAD). In the central ganglia of the cockroach, an average of more that 60 mumoles of GABA are formed from glutamate (Glu) per gram wet weight of tissue per hour. This activity level of the GAD apoenzyme is considerably higher than that found in the central nervous system of crustaceans, amphibians, avians and mammals but is similar to that reported for nervous system tissues from other insect species. A comparison of properties of the crude cockroach enzyme with GAD from crustacean and mammalian origin revealed both similarities and differences: whereas crude cockroach GAD has cofactor requirements and an affinity for Glu substrate (Km 2.8 X 10-2) which are similar to GAD from lobster and mouse, it is uniquely inhibited by both Cl-and by GABA. The GAD from cockroach nervous tissues has two apparent pH optima of which the lower one is preferentially inhibited by a compound which is found in the nerve sheath and the fat body tissue adjacent to ganglia and axons.
mesh_terms: D000613:Aminobutyrates / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002262:Carboxy-Lyases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002490:Central Nervous System / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D003058:Cockroaches; D005724:Ganglia / Q000378:metabolism; D005971:Glutamates; D006863:Hydrogen-Ion Concentration; D009420:Nervous System / Q000201:enzymology / Q000378:metabolism*; D010525:Peripheral Nerves / Q000378:metabolism
chemical_list: D000613:Aminobutyrates; D002712:Chlorides; D005971:Glutamates; D002262:Carboxy-Lyases