Identification of starch-binding domain in α-amylase AmyP

Abstract:

[Objective] To explore whether a starch-binding domain (SBD) locates in the newly identified α-amylase (AmyP) that can degrade raw starches. [Methods] Based on sequence alignment and protein domain prediction, a putative SBD was found in the C-terminal sequence of AmyP. The sequence was cloned, expressed and purified, and the recombinant protein was identified by affinity gel electrophoresis and adsorption on raw starch. [Results] The sequence was defined as an SBD that belongs to the carbohydrate-binding module family 20 (CBM20) based on sequenced similarity. SBD binds with higher affinity to raw rice starch compared to raw corn starch, and is unable to adsorb to raw wheat starch, raw potato starch or raw mungbean starch. [Conclusion] The C-terminal region of AmyP was identified as a novel SBD, which may contribute to the specific raw starch-degarding ability of AmyP.