Biologia, Bratislava, 57/Suppl. 11: 21-27, 2002.
ISSN 0006-3088 (Biologia).
A possible mechanism of catalysis involving three essential residues in the enzymes of a-amylase family.
Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan; tel: ++ 81 6 6879 8605, fax: ++ 81 6 6879 8606, e-mail: firstname.lastname@example.org
Received: October 4, 2001 / Accepted: February 12, 2002
The three-dimensional structures of various types of enzymes of the a-amylase family are briefly reviewed. From the substrate-complexed structures so far known, a consensus structure of the active site consisting of conserved residues has been deduced. Possible roles of the three catalytic residues are discussed, and a reaction scheme is presented. In particular, the role of the aspartic acid (Asp297 in Taka-amylase A) is proposed as crucially working to give rise to distortion at the -1 subsite residue of the substrate. Moreover, a characteristic mode of substrate binding with respect to the (b/a)8-barrel in the amylase enzymes is addressed for further discussion.
Key words: a-amylase family, catalytic mechanism, substrate binding, (b/a)8-barrel, consensus structure.