| 摘要 |
Hybrid alpha-amylases are provided that share a conserved 3D structure in whole or in part with a wild-type Termamyl-like ?-amylase, e.g., a Bacillus amylase. In the hybrid, an N terminal portion of a Termamyl-like ?-amylase is replaced with sequences from an archae ? amylase. The sequence similarity between the two amylase sequences may be less than 60%. Conserving the wild-type 3D structure in the hybrid facilitates obtaining enzymatically active amylases. In one embodiment, one or both amylase sequences contribute residues to the B domain, resulting in particularly advantageous properties. For instance, replacement of the Ca2+ binding site in the B domain of the Termamyl-like ?-amylase with a B domain sequence of an archae ? amylase that does not bind Ca2+ can produce a hybrid that is fully active in the absence of Ca2+.
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