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A mutant α‐amylase with enhanced activity specific for short substrates
Author(s) -
Matsui Ikuo,
Ishikawa Kazuhiko,
Miyairi Sachio,
Fukui Sakuzo,
Honda Koichi
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)81335-j
Subject(s) - mutant , amylase , chemistry , biochemistry , enzyme , gene
The 210th lysine (K210) at the active site in Saccharomycopsis fibuligera α‐amylase was altered to arginine (R) or asparagine (N) by site‐directed mutagenesis. Replacement of K210 by R strengthened the 7th and weakened the 8th subsite affinities. K210 was found to contribute to both the 8th and the 7th subsites. The catalytic activity of the K210R enzyme for the hydrolysis of maltose (G 2 ) was three‐times higher than that of the native enzyme due to an increase in the affinity of the 7th subsite adjacent to the catalytic site, whereas the activity of the K210N enzyme for G 2 was decreased to 1% of that of the native enzyme by a reduction in the 7th subsite affinity.