scholarly journals A Single Residue Change in Vibrio harveyi Hemolysin Results in the Loss of Phospholipase and Hemolytic Activities and Pathogenicity for Turbot (Scophthalmus maximus)

2007 ◽  
Vol 189 (6) ◽  
pp. 2575-2579 ◽  
Author(s):  
Boguang Sun ◽  
Xiao-Hua Zhang ◽  
Xuexi Tang ◽  
Shushan Wang ◽  
Yingbin Zhong ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Enzymatic Activity ◽  
Vibrio Harveyi ◽  
Scophthalmus Maximus ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Virulence Determinant ◽  
Phospholipase B ◽  
Turbot Scophthalmus Maximus

ABSTRACT Vibrio harveyi hemolysin, an important virulence determinant in fish pathogenesis, was further characterized, and the enzyme was identified as a phospholipase B by gas chromatography. Site-directed mutagenesis revealed that a specific residue, Ser153, was critical for its enzymatic activity and for its virulence in fish.

Improvement of stability and enzymatic activity by site-directed mutagenesis of E. coli asparaginase II

2014 ◽  
Vol 1844 (7) ◽  
pp. 1219-1230 ◽  
Author(s):  
Shikha Verma ◽  
Ranjit Kumar Mehta ◽  
Prasanta Maiti ◽  
Klaus-Heinrich Röhm ◽  
Avinash Sonawane
Keyword(s):  
Enzymatic Activity ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
E Coli

scholarly journals Improving the Thermostability of Raw-Starch-Digesting Amylase from a Cytophaga sp. by Site-Directed Mutagenesis

2003 ◽  
Vol 69 (4) ◽  
pp. 2383-2385 ◽  
Author(s):  
Rong-Jen Shiau ◽  
Hui-Chen Hung ◽  
Chii-Ling Jeang
Keyword(s):  
Amino Acids ◽  
Enzymatic Activity ◽  
Half Life ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Wild Type ◽  
Raw Starch ◽  
Heat Stable ◽  
Independent Mechanism

ABSTRACT A heat-stable raw-starch-digesting amylase (RSDA) was generated through PCR-based site-directed mutagenesis. At 65°C, the half-life of this mutant RSDA, which, compared with the wild-type RSDA, lacks amino acids R178 and G179, was increased 20-fold. While the wild type was inactivated completely at pH 3.0, the mutant RSDA still retained 41% of its enzymatic activity. The enhancement of RSDA thermostability was demonstrated to be via a Ca2+-independent mechanism.

A conserved cysteine residue in yeast uroporphyrinogen decarboxylase is not essential for enzymatic activity

1997 ◽  
Vol 43 (8) ◽  
pp. 792-795 ◽  
Author(s):  
Celestino Di Flumeri ◽  
Nicholas H. Acheson ◽  
Teresa Keng
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Enzymatic Activity ◽  
Mutant Strain ◽  
Cysteine Residue ◽  
Catalytic Site ◽  
Heme Biosynthesis ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Decarboxylase Activity ◽  
Uroporphyrinogen Decarboxylase

Uroporphyrinogen decarboxylase catalyzes the fifth step of heme biosynthesis in Saccharomyces cerevisiae. Studies utilizing sulfhydryl-specific reagents suggest that the enzyme requires a cysteine residue within the catalytic site This hypothesis was tested directly by site-directed mutagenesis of highly conserved cysteine-52 to serine or alanine. Plasmids containing these mutations were able to complement a hem6 mutant strain. In addition, properties associated with decreased uroporphyrinogen decarboxylase activity were not detected in the mutant strain transformed with these mutant plasmids. These results suggest that the conserved cysteine-52 by itself is not essential for enzymatic activity.Key words: heme biosynthesis, uroporphyrinogen decarboxylase, site-directed mutagenesis.

Sign in / Sign up

Export Citation Format

Share Document