scholarly journals Characterization of the type I dehydroquinase from Salmonella typhi

1993 ◽  
Vol 295 (1) ◽  
pp. 277-285 ◽  
Author(s):  
J D Moore ◽  
A R Hawkins ◽  
I G Charles ◽  
R Deka ◽  
J R Coggins ◽  
...  
Keyword(s):  
Tertiary Structure ◽  
Salmonella Typhi ◽  
Type I ◽  
Active Site Residues ◽  
X Ray ◽  
E Coli ◽  
Product Mixture ◽  
Secondary And Tertiary Structure ◽  
Nabh4 Reduction

The type I dehydroquinase from the human pathogen Salmonella typhi was overexpressed in an Escherichia coli host and purified to homogeneity. The S. typhi enzyme was characterized in terms of its kinetic parameters, important active-site residues, thermal stability and c.d. and fluorescence properties. In all important respects, the enzyme from S. typhi behaves in a very similar fashion to the well-characterized enzyme from E. coli, including the remarkable conformational stabilization observed on reduction of the substrate/product mixture by NaBH4. This gives confidence that the information from X-ray studies on the S. typhi enzyme [Boys, Fawcett, Sawyer, Moore, Charles, Hawkins, Deka, Kleanthous and Coggins (1992) J. Mol. Biol. 227, 352-355] can be applied to other type I dehydroquinases. Studies of the quenching of fluorescence of the S. typhi enzyme by succinimide show that NaBH4 reduction of the substrate/product imine complex involves a dramatic decrease in the flexibility of the enzyme, with only very minor changes in the overall secondary and tertiary structure.

Sub‐ and Supramolecular X‐Ray Characterization of Engineered Tissues from Equine Tendon, Bovine Dermis, and Fish Skin Type‐I Collagen

2020 ◽  
Vol 20 (5) ◽  
pp. 2000017 ◽  
Author(s):  
Alberta Terzi ◽  
Nunzia Gallo ◽  
Simona Bettini ◽  
Teresa Sibillano ◽  
Davide Altamura ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Skin Type ◽  
Type I ◽  
Fish Skin ◽  
X Ray ◽  
Engineered Tissues

scholarly journals Inducible overproduction of the Aspergillus nidulans pentafunctional AROM protein and the type-I and -II 3-dehydroquinases from Salmonella typhi and Mycobacterium tuberculosis

1992 ◽  
Vol 287 (1) ◽  
pp. 173-181 ◽  
Author(s):  
J D Moore ◽  
H K Lamb ◽  
T Garbe ◽  
S Servos ◽  
G Dougan ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Aspergillus Nidulans ◽  
Sole Carbon Source ◽  
Double Mutant ◽  
Salmonella Typhi ◽  
Type I ◽  
Type Ii ◽  
E Coli ◽  
Heat Stable ◽  
Km Value

The aroQ gene of Mycobacterium tuberculosis, encoding a type-II 3-dehydroquinase, and the aroD gene of Salmonella typhi, encoding a type-I 3-dehydroquinase, have been highly overexpressed in Escherichia coli using the powerful trc promoter contained within the expression vector pKK233-2. The M. tuberculosis type-II 3-dehydroquinase has been purified in bulk from overproducing strains of E. coli to greater than 95% homogeneity. The protein is extremely heat-stable, is active as a homododecamer and has the lowest reported Km value of any type-II 3-dehydroquinase. The pentafunctional aromA gene of Aspergillus nidulans has been overexpressed more than 120-fold in an A. nidulans aromA- qutB- double mutant from a truncated quinate-inducible qutE promoter, such that the AROM protein is visible as a significant fraction (approx. 6%) in cell-free crude extracts. The M. tuberculosis aroQ gene has been fused to the same truncated qutE promoter and shown to encode quinate-inducible 3-dehydroquinase activity that allows a qutE- mutant strain of A. nidulans to utilize quinate as sole carbon source.

scholarly journals Preparation and Characterization of Chitosan Nanocomposite Based on Nanoscale Silver and Nanomontmorillonite

2019 ◽  
Vol 2 (2) ◽  
pp. 5-12 ◽  
Author(s):  
Fatemeh- Sadat Ebnerasool ◽  
Negar Motakef Kazemi
Keyword(s):  
Food Packaging ◽  
Solution Method ◽  
In Situ Synthesis ◽  
Diffusion Method ◽  
X Ray ◽  
E Coli ◽  
Packaging Industry ◽  
Scanning Electron

The chitosan nanocomposites were rapidly prepared by simple solution method. This biopolymer matrix was modified by prepared nanoscale silver (Ag) using in situ synthesis from precursor and nanomontmorillonite (NMMT). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and energy dispersive x-ray spectroscopy (EDX). The water vapor properties (WVP) of nanocomposites were investigated using gravimetric standard. The antibacterial activity of nanocomposite was measured by the well diffusion method on Muller–Hinton Agar against Escherichia coli (E. coli) by zone inhibition. Based on the obtained results, the nanocomposite can have a good candidate for different applications and food packaging industry.

Bio-Synthesis and Characterization of CS–Ag Nano Hydrogel for Antibacterial Application

2020 ◽  
Vol 12 (4) ◽  
pp. 542-547
Author(s):  
Shikha Sharma ◽  
Fehmeeda Khatoon
Keyword(s):  
Ag Nanoparticles ◽  
Spectroscopic Method ◽  
Inhibition Zone ◽  
Plant Leaves ◽  
X Ray Diffraction ◽  
X Ray ◽  
E Coli ◽  
Optimum Wavelength ◽  
Xrd Method

An environmental technique of herbal mediated blend of Ag nanoparticles is a substantial stage in the ground of nanotechnology. Chitosan (CS) is a polymer which is biocompatible and antibacterial. In this work, we have synthesized CS–Ag Nano hydrogel which is form with chitosan-based hydrogel merged in the herbal synthesized Ag nanoparticles. These green synthesized Ag-nanoparticles made from Polygonum bistorta plant leaves and described with the assistance of UV-vis spectrophotometer, and Dynamic Light Scattering (DLS). In this work our main focus to synthesized CS–Ag Nano hydrogel. These hydrogel was described by Fourier transform infrared (FTIR) spectroscopic method, X-ray diffraction (XRD) method, and contact angle. Nanoparticle size distribution was within 1 to 100 nm by DLS and the optimum wavelength was noted in 400 to 450 nm by UV-vis spectroscopic readings. A good antibacterial behavior has been displayed by these synthesized CS–Ag Nano hydrogel films against both E. coli (gram –ve) and S. aureus (gram +ve) with the maximum 7 mm inhibition zone.

scholarly journals SYNTHESIS, CHARACTERIZATION OF ANTIMICROBIAL ACTIVITY OF 22’DICHLOROHYDROBENZOIN

2018 ◽  
Vol 11 (12) ◽  
pp. 334
Author(s):  
Thanuja B ◽  
Charles Kanagam
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Activities ◽  
Diffusion Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
E Coli ◽  
Vis Spectroscopy ◽  
Optical Behavior ◽  
Thermal Stability Of

Objective: The objective of this work to evaluate the antimicrobial activities of synthesized 22’dichlorohydrobenzoin (22’CD) a new organic crystal.Methods: 22’CD a new organic crystal was grown by vapor diffusion method. Single crystals of 22’CD have been subjected to X-ray diffraction analysis to estimate the lattice parameters and the space group. The molecular structure was confirmed using Fourier transform infrared and nuclear magnetic resonance (NMR) spectral analyses. Optical behavior and thermal stability of the crystal were determined using UV-Vis spectroscopy and thermogravimetry-differential thermal analysis curves. In the present study, antimicrobial activity of 22’CD was evaluated against Escherichia coli and Bacillus subtilis was evaluated by agar well diffusion method.Results: Antibacterial activity of 22’CD was analyzed with ciprofloxacin and miconazole standard and tested against E. coli, Pseudomonas aeruginosa, Salmonella paratyphi, Klebsiella pneumonia’s, Staphylococcus aureus, Streptococcus progenies, and B. subtilis.Conclusion: The 22’CD was found to be effective against E. coli and B. subtitles.

Salt bridges at the subdomain interfaces of the adenylation domain and active-site residues of Mycobacterium tuberculosis NAD+-dependent DNA ligase A (MtbLigA) are important for the initial steps of nick-sealing activity

2021 ◽  
Vol 77 (6) ◽  
Author(s):  
Mohammad Afsar ◽  
Ankita Shukla ◽  
Nelam Kumar ◽  
Ravishankar Ramachandran
Keyword(s):  
Active Site ◽  
Dna Ligase ◽  
Temperature Sensitive ◽  
Salt Bridges ◽  
Active Site Residues ◽  
X Ray ◽  
E Coli ◽  
Ligation Reaction ◽  
Dna Substrate

NAD+-dependent DNA ligase (LigA) is the principal bacterial ligase and catalyses a multistep ligation reaction. The adenylation (AdD) domain at the N-terminus consists of subdomains 1a and 1b, where subdomain 1a is unique to LigA. Small-angle X-ray scattering and X-ray diffraction studies were used to probe changes in the relative spatial dispositions of the two subdomains during the adenylation reaction. Structural analyses of the inter-subdomain interactions of the AdD domain suggest that salt bridges formed by Glu22, Glu26 and Glu87 of subdomain 1a with Arg144, Arg315 and His240 of subdomain 1b play an important role in stabilizing the intermediate conformations of the two subdomains. E22A, E26A and E87A mutations reduce the in vitro activity by 89%, 64% and 39%, respectively, on a nicked DNA substrate, while they show no activity loss on a pre-adenylated DNA substrate, thus suggesting that the salt bridges are important in the initial steps of the ligation reaction. Furthermore, the E22A, E26A and E87A mutants exhibited extremely delayed growth in complementation assays involving the Escherichia coli GR501 strain, which harbours its own temperature-sensitive LigA. The H236A and H236Y mutants, which involve the residue that stacks against the adenine moiety of AMP, severely impact the activity and the ability to complement the growth-defective E. coli GR501 strain. Analysis of the K123A and K123R mutations in the active site rationalizes their total loss of activity and inability to rescue the growth-defective E. coli GR501 strain.

Secondary and tertiary structure prediction of fenugreek (Trigonella foenum-graecum) protein

2016 ◽  
Vol 39 (1) ◽  
Author(s):  
Sharda Choudhary ◽  
Ravindra Singh ◽  
R. S. Meena ◽  
Geetika Jethra
Keyword(s):  
Structure Prediction ◽  
Tertiary Structure ◽  
Transmembrane Protein ◽  
Protein Domain ◽  
E Coli ◽  
Trigonella Foenum Graecum ◽  
Lab Experiments ◽  
Wet Lab ◽  
Protein Models ◽  
Secondary And Tertiary Structure

<italic>In-silico</italic> development of protein models in fenugreek (<italic>Trigonella foenum-graecum</italic>) has opened up new vistas using the modern computational tools. The identification of protein in fenugreek having homology with the protein domain of humans and E-coli shows that the database available on Apiaceae family are very low. The estimated molecular weight of identified for fenugreek AM-1 protein was 11372.8 and was predicted as basic. A channel in fenugreek transmembrane protein has been identified through which a ligand (an ion or a small molecule) might pass. The present finding may be a valuable addition to the proteomic information available on fenugreek. Further validation can be performed using wet lab experiments.

scholarly journals Characterization of Primed Adaptation in the Escherichia coli type I-E CRISPR-Cas System

2020 ◽  
Author(s):  
Anne M. Stringer ◽  
Lauren A. Cooper ◽  
Sujatha Kadaba ◽  
Shailab Shrestha ◽  
Joseph T. Wade
Keyword(s):  
Escherichia Coli ◽  
Nucleic Acid ◽  
Genetic Locus ◽  
Type I ◽  
Cornell University ◽  
E Coli ◽  
Nucleic Acid Molecule ◽  
Bacterial Immune Systems ◽  
Insight Into

ABSTRACTCRISPR-Cas systems are bacterial immune systems that target invading nucleic acid. The hallmark of CRISPR-Cas systems is the CRISPR array, a genetic locus that includes short sequences known as “spacers”, that are derived from invading nucleic acid. Upon exposure to an invading nucleic acid molecule, bacteria/archaea with functional CRISPR-Cas systems can add new spacers to their CRISPR arrays in a process known as “adaptation”. In type I CRISPR-Cas systems, which represent the majority of CRISPR-Cas systems found in nature, adaptation can occur by two mechanisms: naïve and primed. Here, we show that, for the archetypal type I-E CRISPR-Cas system from Escherichia coli, primed adaptation occurs at least 1,000 times more efficiently than naïve adaptation. By initiating primed adaptation on the E. coli chromosome, we show that spacers can be acquired across distances of >100 kb from the initially targeted site, and we identify multiple factors that influence the efficiency with which sequences are acquired as new spacers. Thus, our data provide insight into the mechanism of primed adaptation.[This paper has been peer reviewed, with Ailong Ke (Cornell University) serving as the editor. Reviews and point-by-point response, and a marked-up version of the edited manuscript are provided as supplementary files.]

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