Enhancement of the thermostability of the maltogenic amylase MAUS149 by Gly312Ala and Lys436Arg substitutions.
Bioresour Technol
; 102(2): 1740-6, 2011 Jan.
Article
em En
| MEDLINE
| ID: mdl-20855205
ABSTRACT
Based on sequence alignments and homology modeling, Gly 312 and Lys 436 of the maltogenic amylase from Bacillus sp. US149 (MAUS149) were selected as targets for site-directed mutagenesis to improve the thermostability of the enzyme. Variants of MAUS149 with amino acid substitutions G312A, K436R and G312A-K436R had substrate specificities, kinetic parameters and pH optima similar to those of the wild-type enzyme; however, the enzymes with substitutions K436R and G312A-K436R, had an optimal temperature of 45 °C instead of the 40 °C for the wild-type enzyme. The half-life time at 55 °C increased from 15 to 25 min for the double mutant. Molecular modeling suggests that the increase in thermostability was due to new hydrophobic interactions and the formation of a salt bridge and hydrogen bond in the G312A and K436R variants, respectively. The double mutant could be a potential candidate for application in the bread industry.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Temperatura
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Bacillus
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Mutagênese Sítio-Dirigida
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Substituição de Aminoácidos
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Aminoácidos
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Glicosídeo Hidrolases
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article