Characteristics of two forms of alpha-amylases and structural implication.
Complete (Ba-L) and truncated (Ba-S) forms of alpha-amylases from Bacillus subtilis X-23 were purified, and the amino- and carboxyl-terminal amino acid sequences of Ba-L and Ba-S were determined. The amino acid sequence deduced from the nucleotide sequence of the alpha-amylase gene indicated that Ba-S was produced from Ba-L by truncation of the 186 amino acid residues at the carboxyl-terminal region. The results of genomic Southern analysis and Western analysis suggested that the two enzymes originated from the same alpha-amylase gene and that truncation of Ba-L to Ba-S occurred during the cultivation of B. subtilis X-23 cells. Although the primary structure of Ba-S was approximately 28% shorter than that of Ba-L, the two enzyme forms had the same enzymatic characteristics (molar catalytic activity, amylolytic pattern, transglycosylation ability, effect of pH on stability and activity, optimum temperature, and raw starch-binding ability), except that the thermal stability of Ba-S was higher than that of Ba-L. An analysis of the secondary structure as well as the predicted three-dimensional structure of Ba-S showed that Ba-S retained all of the necessary domains (domains A, B, and C) which were most likely to be required for functionality as alpha-amylase.
Ohdan
K
K
Biochemical Research Laboratory, Ezaki Glico Co., Ltd., Utajima 4-6-5, Nishiyodogawa-ku, Osaka 555-8502, Japan.
Kuriki
T
T
Kaneko
H
H
Shimada
J
J
Takada
T
T
Fujimoto
Z
Z
Mizuno
H
H
Okada
S
S
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology*; D015139:Blotting, Southern; D015153:Blotting, Western; D003001:Cloning, Molecular; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D013213:Starch / Q000378:metabolism; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
D013213:Starch; D000516:alpha-Amylases