Pop2, a component of the Ccr4-Not complex, functions as a deadenylase both in vitro and in vivo. In this research, we found that the recombinant human Pop2 (hPop2) mainly existed in a compact monomeric state with a alpha + beta tertiary structure type. The percentages of the secondary structures evaluated from the CD spectrum were about 37% alpha-helix, 14% beta-sheet, and 19% beta-turns. The optimal condition for hPop2 catalysis was pH 7-8 at 37 degrees C. Mg2+, Mn2+ and Co2+ had similar effects on the deadenylation activity of hPop2, and the optimal concentration was 0.3-0.5 mM. The deadenylase activity of hPop2 was, at least partially, specific when coordinated with divalent metal ions. The enzyme was not inhibited much by the nucleoticle analogs, and the product 5'-AMP was the most efficient inhibitor. The dissimilarity in the metal ion dependence and inhibitory effects of the nucleoticle analogs suggested that various deadenylases might have differential regulation mechanisms. (c) 2008 Elsevier Inc. All rights reserved.