Structural and functional characterization of recombinant medaka fish alpha-amylase expressed in yeast Pichia pastoris.
Mizutani, K., Toyoda, M., Otake, Y., Yoshioka, S., Takahashi, N., Mikami, B.(2012) Biochim Biophys Acta 1824: 954-962
- PubMed: 22613096 
- DOI: https://doi.org/10.1016/j.bbapap.2012.05.005
- Primary Citation of Related Structures:  
3VM5 - PubMed Abstract: 
The medaka fish α-amylase was expressed and purified. The expression systems were constructed using methylotrophic yeast Pichia pastoris, and the recombinant proteins were secreted into the culture medium. Purified recombinant α-amylase exhibited starch hydrolysis activity. The optimal pH, denaturation temperature, and K(M) and V(max) values were determined; chloride ions were essential for enzyme activity. The purified protein was also crystallized and examined by X-ray crystallography. The structure has the (α/β)(8) barrel fold, as do other known α-amylases, and the overall structure is very similar to the structure of vertebrate (human and pig) α-amylases. A novel expression plasmid was developed. Using this plasmid, high-throughput construction of an expression system by homologous recombination in P. pastoris cells, previously reported for membrane proteins, was successfully applied to the secretory protein.
Organizational Affiliation: 
Graduate School of Agriculture, Kyoto University, Kyoto, Japan. kmizutani@kais.kyoto-u.ac.jp