Characteristics of the enzyme N-acetyltransferase in the optic lobe of the giant freshwater prawn, Macrobrachium rosenbergii de Man
1992
Boonsirm Withyachumnarnkul | Anchalee Pongsa-Asawapaiboon | Boonserm Poolsanguan (Mahidol Univ., Bangkok (Thailand). Faculty of Science. Dept. of Anatomy)
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. Using tryptamine as substrate, Vmax of the optic lobe NAT was much higher than that of the rat pineal NAT (294 vs. 0.72 pmol/hr/ug protein) and Km of the optic lobe NAT was much less than that of the rat pineal NAT (14.5 vs. 4,400 micro M). At 25 deg C, the enzyme activity was maximal at pH 6.5. The enzyme catalyzed reaction when substrates were arylalkylamines and very low Km was obtained when tryptamine was used as substrate. The results indicate that the optic lobe NAT differed kinetically from the rat pineal NAT, but is similar to in term of being arylalkylamine NAT.
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