The DNA fragment encoding β-hexosaminidase was synthesized, and cloned into pET-28a vector. 
pET-28a
The constructed plasmid pMD18-T-β-hexosaminidase was transformed into E. coli Top 10 and followed by expression of the protein induced by IPTG. 
IPTG
SDS-PAGE result showed that the relative molecular mass of the recombinant protein was about M, 55 000. 
SDS-PAGE