A small chimerically bifunctional monomeric protein: Tapes japonica lysozyme

A small chimerically bifunctional monomeric protein: Tapes japonica lysozyme
September 2003
Received 25 February 2003; received after revision 29 May 2003; accepted 12 June 2003
K. Takeshita1, Y. Hashimoto1, T. Ueda1 and T. Imoto1, 2
Cellular and Molecular Life Sciences (CMLS)
Issue: Volume 60, Number 9
SpringerLink
(1) Graduate School of Pharmaceutical Sciences, Kyushu University, 812-8582 Fukuoka, Japan
(2) Department of Applied Microbial Technology, Faculty of Engineering, Sojo University, 860-0082, Ikeda 4-22-1, Kumamoto, Japan
Abstract The lysozyme of the marine bilave Tapes japonica (13.8 kDa) is a novel protein. The protein has 46% homology with the destabilase from medicinal leech that has isopeptidase activity. Based on these data, we confirmed hydrolysis activity of T. japonica lysozyme against three substrates: L--Glu-pNA, D--Glu-pNA, and -(-Glu)-L-Lys. The optimal pH of chitinase and isopeptidase activity was 5.0 and 7.0, respectively. The isopeptidase activity was inhibited with serine protease inhibitor, but the lytic and chitinase activities were not. Moreover, only isopeptidase activity is decreased by lyophilization, but lytic and chitinase activities were not. We conclude that T. japonica lysozyme expresses isopeptidase and chitinase activity at different active sites.
Lysozyme - Tapes japonica - chitinase - isopeptidase - invertebrate lysozyme - bifunctional
T. Imoto
Email: Imoto@phar.kyushu-u.ac.jp
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