title: Acetyl CoA generation and N-acetylation of serotonin (5HT) in the mosquito, Aedes togoi.
abstract: Acetyl CoA synthetase (ACS; EC 6.2.1.1) was studied in the mosquito, Aedes togoi, by a novel assay which coupled the acetyl-CoA generated to p-aminosalicylic acid (ASA). The N-acetylated product was determined by an HPLC-fluorimetric procedure. High ACS activity was observed in the newly-pupated pupae of both sexes and in the adult male mosquito whose activity was five times that of the female. Acetyl CoA-dependent N-acetyltransferase (NAT; EC 2.3.1.5) activity toward serotonin (5HT) was also studied using HPLC-electrochemical detection (HPLC-ECD). A progressive increase in the 5HT-NAT activity was observed from the fourth-instar larvae to the adult mosquito with the latter showing 6-fold higher activity in the head compared to the abdomen-thorax region. Kinetic studies on the pupal enzyme extracts showed that the apparent Km values for 5HT and acetyl CoA were 63 and 66 microM respectively. Tryptamine inhibited 5HT-NAT non-competitively with a Ki value of 8 microM.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, National University of Singapore, Kent Ridge.
authors.forename: H G
authors.initials: HG
authors.lastname: Khoo
authors.forename: K P
authors.initials: KP
authors.lastname: Wong
mesh_terms: D010129:4-Aminobenzoic Acid / Q000494:pharmacology; D000106:Acetate-CoA Ligase / Q000378:metabolism*; D000105:Acetyl Coenzyme A / Q000378:metabolism*; D000107:Acetylation; D000330:Aedes / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D010131:Aminosalicylic Acid; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism; D015306:Biogenic Monoamines / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D006868:Hydrolysis; D007700:Kinetics; D007814:Larva / Q000378:metabolism; D008099:Liver / Q000737:chemistry; D008297:Male; D011679:Pupa / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000032:analysis / Q000378:metabolism*
chemical_list: D015306:Biogenic Monoamines; D012701:Serotonin; D010131:Aminosalicylic Acid; D000105:Acetyl Coenzyme A; D001191:Arylamine N-Acetyltransferase; D000106:Acetate-CoA Ligase; D010129:4-Aminobenzoic Acid