Purification, characterization, and nucleotide sequence of an intracellular maltotriose-producing α-amylase from Streptococcus bovis 148

Abstract

An intracellular α-amylase from Streptococcus bovis 148 was purified and characterized. The enzyme was induced by maltose and soluble starch and produced about 80% maltotriose from soluble starch. Maltopentaose was hydrolyzed to maltotriose and maltose and maltohexaose was hydrolyzed mainly to maltotriose by the enzyme. Maltotetraose, maltotriose, and maltose were not hydrolyzed. This intracellular enzyme was considered to be a maltotriose- producing enzyme. The enzymatic characteristics and hydrolysis product from soluble starch were different from those of the extracellular raw-starch- hydrolyzing α-amylase of strain 148. The deduced amino acid sequence of the intracellular α-amylase was similar to the sequences of the mature forms of extracellular liquefying α-amylases from Bacillus strains, although the intracellular α-amylase did not contain a signal peptide. No homology between the intracellular and extracellular α-amylases of S. bovis 148 was observed.