Biologia, Bratislava, 57/Suppl. 11: 77-82, 2002.

ISSN 0006-3088 (Biologia).


Full Paper

Three dimensional structure of Bacillus stearothermophilus neopullulanase.


Hironori Hondoh1*, Takashi Kuriki2 & Yoshiki Matsuura1

1 Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; tel.: ++ 81 6 6879 8605, fax :++ 81 6 6879 8606, e-mail:

2 Biochemical Research Laboratory, Ezaki Glico Co. Ltd., 4-6-5 Utajima, Nishiyodogawa-ku, Osaka 555-8502, Japan

* corresponding author

Received: October 4, 2001 / Accepted: May 10, 2002



The three-dimensional structure of B. stearothermophilus neopullulanase has been determined by X-ray diffraction at 1.9 resolution. The enzyme forms a dimer in the crystal, the monomer being composed of four domains N, A, B, and C. The structure of the active site cleft of a monomer is shallow and wide compared to other a-amylase enzymes. The dimer is formed by monomers folded to make contact with each other via domains N, A and B, making the cleft apparently deeper and narrower. The shape of the cleft in the dimer is slightly different among the enzymes of the subgroup, possibly reflecting the differences in substrate specificities.


Key words: neopullulanase, X-ray structure, Bacillus stearothermophilus, (b/a)8-barrel, pullulan, cyclomaltodextrinase, a-amylase family.