N-Acetylphenylalanyl-tRNA hydrolase from Artemia. Identification of two molecular forms and their evolution during early differentiation.

This paper describes the properties of a N-acetylphenylalanyl-tRNA hydrolase present in Artemia which splits N-acetylphenylalanyl-tRNA to N-acetylphenylalanine and tRNA. The hydrolase is highly specific with respect to its substrate, is maximally active in the presence of a divalent cation (Mg2+, Mn2+ or Ca2+) and has a pH optimum at around neutrality. By chromatography on DEAE-Sephadex have been isolated two molecular forms of the enzyme which differ in their molecular sizes (35 000 and 70 000), heat sensitivity and metal requirements. While the total activity of the hydrolase remains constant during embryogenesis and early larval development, the amount of lighter form of the enzyme significantly decreases, with a concomitant increase of the heavier isozyme.