title: Characterization of arylalkylamine N-acetyltransferase (AANAT) activities and action spectrum for suppression in the band-legged cricket, Dianemobius nigrofasciatus (Orthoptera: Gryllidae).
abstract: Arylalkylamine N-acetyltransferase (AANAT), constituting a large family of enzymes, catalyzes the transacetylation from acetyl-CoA to monoamine substrates, although homology among species is not very high. AANAT in vertebrates is photosensitive and mediates circadian regulation. Here, we analyzed AANAT of the cricket, Dianemobius nigrofasciatus. The central nervous system contained AANAT activity. The optimum pHs were 6.0 (a minor peak) and 10.5 (a major peak) with crude enzyme solution. We analyzed the kinetics at pH 10.5 using the sample containing collective AANAT activities, which we term AANAT. Lineweaver-Burk plot and secondary plot yielded a K(m) for tryptamine as substrate of 0.42 microM, and a V(max) of 9.39 nmol/mg protein/min. The apparent K(m) for acetyl-CoA was 59.9 microM and the V(max) was 8.14 nmol/mg protein/min. AANAT of D. nigrofasciatus was light-sensitive. The activity was higher at night-time than at day-time as in vertebrates. To investigate most effective wavelengths on AANAT activity, a series of monochromatic lights was applied (350, 400, 450, 500, 550, 600 and 650 nm). AANAT showed the highest sensitivity to around 450 nm and 550 nm. 450 nm light was more effective than 550 nm light. Therefore, the most effective light affecting AANAT activity is blue light, which corresponds to the absorption spectrum of blue wave (BW)-opsin.
authors.affiliation: Graduate School of Agricultural Science, Kobe University, Nada, Japan.
authors.forename: Norimitsu
authors.initials: N
authors.lastname: Izawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Watanabe
authors.forename: Makio
authors.initials: M
authors.lastname: Takeda
mesh_terms: D000105:Acetyl Coenzyme A / Q000737:chemistry; D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000378:metabolism* / Q000528:radiation effects; D002490:Central Nervous System / Q000201:enzymology; D006135:Gryllidae / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D012680:Sensitivity and Specificity; D013053:Spectrophotometry; D013997:Time Factors; D014363:Tryptamines / Q000737:chemistry
chemical_list: D014363:Tryptamines; C030820:tryptamine; D000105:Acetyl Coenzyme A; D047068:Arylalkylamine N-Acetyltransferase