Sweet potato beta-amylase. Primary structure and identification of the active-site glutamyl residue.
The complete amino acid sequence of a subunit of sweet potato beta-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-carboxymethylated 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 beta-amylases from soybean and barley, while it about 25% with those of three bacterial beta-amylases deduced from the cDNA sequences. Sweet potato beta-amylase was completely inactivated with 2,3-epoxypropyl alpha-D-[U-14C]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 beta-amylase.
Toda
H
H
Institute for Protein Research, Osaka University, Japan.
Nitta
Y
Y
Asanami
S
S
Kim
J P
JP
Sakiyama
F
F
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide; D004591:Electrophoresis, Polyacrylamide Gel; D005960:Glucosides / Q000494:pharmacology; D005971:Glutamates / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D018698:Glutamic Acid; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000378:metabolism; D014675:Vegetables / Q000201:enzymology*; D001614:beta-Amylase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism
D000596:Amino Acids; D005960:Glucosides; D005971:Glutamates; C007607:2',3'-epoxypropylglucopyranoside; D018698:Glutamic Acid; D001614:beta-Amylase; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; C036813:lysyl endopeptidase; D003488:Cyanogen Bromide