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Results 1 - 5 of 5
EC Number
Amino acid exchange
Commentary
Reference
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construction of beta-lactamase (AmpC) and cephalosporin acetyl esterase (Aes) single or double knockout mutant strains from Escherichia coli strains JM105 and JM109(DE3), the chromosomal genes ampC and aes are disrupted by the phage lambda red recombinase system, which involves three stepswith three helper plasmids pKD13, pKD46 and pCP20, single or double knockout of ampC and aes from Escherichia coli JM105 have minimal effects on formal growth of the recombinant cells. Recombinant expression of Pseudomonas sp. strain SE83 cephalosporin C acylase II (sCPCAcy), EC 3.5.1.93, from vector pMKC-sCPCacy restores the cephalosporin C decomposition activity to an even higher level compared to wild-type, overview. CPC acylase II catalyzes a one-step enzymatic conversion of cephalosporin C into 7-aminocephalosporanic acid
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construction of truncation variants lacking four and ten residues of the N-terminal region. The truncations do not affect the secondary structure or the fold but modulate the oligomerization dynamics. A modest in substrate specificity for acetylated xylose is observed compared with acetylated glucose. Variants show a drastic reduction of 30-40C in the optimum temperature for activity
P228A
the mutation does not affect the overall secondary, tertiary, and quaternary structures and moderately decreases the thermal stability. However, the wild type cis conformation of the 227-228 peptide bond adopts a trans conformation in the variant. The results suggest that the conserved proline residue is responsible for the cis conformation of the peptide and shapes the geometry of the active site. Elimination of the pyrrolidine ring results in the loss of van der Waals and hydrophobic interactions with both the alcohol and acyl moeities of the ester substrate, leading to significant impairment of the activity and perturbation of substrate specificity; the mutation does not affect the overall secondary, tertiary, and quaternary structures, but has a significantly decreasing effect on the activity and moderately decreases the thermal stability of the enzyme. The wild type cis conformation of the 227-228 peptide bond adopts a trans conformation in the variant
S188A
active site knockout
synthesis
synthesis of peracetic acid. Recombinant enzyme can be efficiently produced in a low-cost autoinduction medium with an activity of 6800 U/ml. Optimal synthesis of peracetic is achieved with 0.30 mg/ml crude enzyme, 300 mM glycerol triacetate, and 1 M hydrogen peroxide, pH 8.0, and 2C, which produces approximately 150 mM of peracetic acid within 5 min. When immobilized on an acrylate amino resin, the activity of the immobilized enzyme is 383.7 U/g
Results 1 - 5 of 5