Open AccessSweet potato β‐amylase
Author(s) -
TODA Hiroko,
NITTA Yasunori,
ASANAMI Shogo,
KIM Jun Pyong,
SAKIYAMA Fumio
Publication year - 1993
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1993.tb18112.x
Subject(s) - cyanogen bromide , biochemistry , peptide sequence , protease , chemistry , amylase , enzyme , protein subunit , amino acid , biology , gene
The complete amino acid sequence of a subunit of sweet potato β‐amylase, a homotetramer, was established by sequence analysis of peptides obtained by digestions with Achromobacter protease I and Staphylococcus aureus V8 protease and by cyanogen bromide cleavage of the S ‐carboxyme‐thylated subunit. The subunit of the enzyme is a single polypeptide consisting of 498 amino acid residues. It showed 50–60% identity in the amino acid sequence with those of β‐amylases from soybean and barley, while it about 25% with those of three bacterial β‐amylases deduced from the cDNA sequences. Sweet potato β‐amylase was completely inactivated with 2,3‐epoxypropyl α‐ d ‐[U‐ 14 C]glucopyranoside. Sequence analysis of the inactivated enzyme revealed that Glu187 was specifically esterified by the affinity labeling with the above reagent, proposing that Glu187 is a potent candidate involved directly in the catalysis with this plant β‐amylase.