Characteristics of the enzyme N-acetytransferase in the optic lobe of the giant freshwater prawn, Macrobrachium rosenbergii de Man

Abstract

1. 1. The enzyme N-acetyltransferase (NAT) in the optic lobe of the giant freshwater prawn, Macrobrachium rosenbergii de Man, was characterized and compared to NAT of the rat pineal. 2. 2. Using tryptamine as substrate, the optic lobe NAT had a Vmax400-fold higher, and a Km300-fold lower, than that of the pineal NAT. 3. 3. At 25°C, the optic lobe NAt activity was maximal at pH 6.5 and stable up to 3 hr without significant loss of activity. 4. 4. The optic lobe NAT requires arylalkylamines as substrates. 5. 5. The results indicate that the optic lobe NAT differs kinetically from the rat pineal NAT and suggest that it is an arylalkylamine NAT. © 1993.