Cloning, characterization and tissue expression of disk abalone (Haliotis discus discus) catalase Prashani Mudika Ekanayake a,1 , Mahanama De Zoysa a,1 , Hyun-Sil Kang a , Qiang Wan a , Youngheun Jee c , Youn-Ho Lee d , Sang-Jin Kim d , Jehee Lee a,b, * a Department of Marine Biotechnology, Cheju National University, 66 Jejudaehakno, Jeju 690-756, Republic of Korea b Marine and Environmental Institute, Cheju National University, Jeju 690-814, Republic of Korea c Department of Veterinary Medicine, Cheju National University, 66 Jejudaehakno, Jeju, 690-756, Republic of Korea d Korea Ocean Research and Development Institute, Sa 2-dong, Ansan, 426-744, Republic of Korea Received 5 July 2007; revised 8 November 2007; accepted 8 November 2007 Available online 22 November 2007 KEYWORDS Abalone; Antioxidant; Catalase; cDNA; H 2 O 2 ; Reactive oxygen species; Tissue expression Abstract Catalase is an antioxidant enzyme that plays a significant role in protection against oxidative stress by detoxification of hydrogen peroxide (H 2 O 2 ). A gene coding for a putative catalase was isolated from the disk abalone (Haliotis discus discus) cDNA library and denoted as Ab-catalase. The full-length (2864 bp) Ab-catalase cDNA contained 1,503 bp open reading frame (ORF), encoding 501 amino acid residues with 56 kDa predicted molecular weight. The deduced amino acid sequence of Ab-catalase has characteristic features of catalase family such as catalytic site motif ( 61 FNRERIPERVVHAKGAG 77 ), heme-ligand signature motif ( 351 RLY- SYSDT 358 ), NADPH and heme binding residues. Phylogenetic and pairwise identity results indicated that Ab-catalase is more similar to scallop (Chlamys farreri) catalase with 80% amino acid identity except for other reported disk abalone catalase sequences. Constitutive Ab- catalase expression was detected in gill, mantle, gonad, hemocytes, abductor muscle and digestive tract in tissue specific manner. Ab-catalase mRNA was up-regulated in gill and diges- tive tract tissues for the first 3 h post injection of H 2 O 2 , showing the inducible ability of aba- lone catalase against oxidative stress generated by H 2 O 2 . The purified recombinant catalase showed 30,000 U/mg enzymatic activity against H 2 O 2 and biochemical properties of higher thermal stability and broad spectrum of pH. Our results suggest that abalone catalase may play an important role in regulating oxidative stress by scavenging H 2 O 2 . ª 2007 Elsevier Ltd. All rights reserved. Introduction Reactive oxygen species (ROS) such as singlet oxygen ( 1 O 2 ), superoxide anion (O 2 $ ), hydrogen peroxide (H 2 O 2 ), and * Corresponding author. Department of Marine Biotechnology, Cheju National University, 66 Jejudaehakno, Jeju 690-756, Repub- lic of Korea. Tel.: þ82 64 754 3472; fax: þ82 64 756 3493. E-mail address: jehee@cheju.ac.kr (J. Lee). 1 These authors contributed equally to this work. 1050-4648/$ - see front matter ª 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.fsi.2007.11.007 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/fsi Fish & Shellfish Immunology (2008) 24, 267e278