Purification and analysis of the structure of alpha-galactosidase from Escherichia coli

Alpha-Galactosidase, the product of the melA gene, was purified from a strain of Escherichia coli harboring a plasmid carrying melA, which over-produced the alpha-galactosidase. An apparent molecular weight was determined to be 50 kDa. The amino acid composition of this enzyme was determined. The result indicates that this enzyme is a hydrophilic and acidic protein. We have subjected the purified enzyme to 20 cycles of N-terminal sequence analysis. This verified the translation start site of the melA gene and the predicted N-terminal sequence.