|
KMID : 0545120010110010118
|
|
Journal of Microbiology and Biotechnology
2001 Volume.11 No. 1 p.118 ~ p.123
|
|
|
Effect of His 192 Mutation on the Activity of Alginate Lyase A1-III from Sphingomonas Species A1
|
|
YOON, HYE-JIN
CHOI, YONG-JIN/MIYAKE, OSAMU/HASHIMOTO, WATARU/MURATA, KOUSAKU/MIKAMI, BUNZO
|
|
|
Abstract
|
|
|
|
The alginate lyase A1-Ⅲ gene of Sphingomonas species A1 is composed of 1,077 nucleotides, encoding a protein (359 amino acids) with a molecular mass of 40,322Da. Recombinant A1-Ⅲ expressed in Escherichia coli exhibited the same full enzymatic activity as native A1-Ⅲ. In order to identify the critical residue for activity, a site-directed mutation was introduced into the A1-Ⅲ gene (H192A, His192→Ala). Recombinant A1-Ⅲ (H192A) exhibited a significant decrease in enzyme activity (one-thirty thousandth of that of A1-Ⅲ), without any conformational change, as detected by the CD spectra in the far UV region. Also, the chemical modification of wild-type Al-III with methyl 4-nitro benzene sulfonate resulted in a 40% decrease from the initial activity, whereas the same modification of A1-Ⅲ (H192A) produced no change in the activity. The role of His192 on the catalytic process was also explored based on a model of A1-Ⅲ docked with mannuronic acid into the active site.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
  
|
|