New Ribozyme-Mimics Employing Mg(II) Ion As Catalytic Center

2001 ◽  
Vol 30 (6) ◽  
pp. 584-585 ◽  
Author(s):  
Akinori Kuzuya ◽  
Ryo Mizoguchi ◽  
Makoto Komiyama
Keyword(s):  
Catalytic Center ◽  
Ribozyme Mimics

m-[o-(2-Chloro-5-Fluorosulfonylphenylureido)Phenoxybutoxy]Benzamidine: Affinity Labeling Reagent Which Can Identify Secondary Binding Sites of Coagulation Complement and Fibrinolytic Serine Proteases

1979 ◽  
Author(s):  
D Bing ◽  
D Robison ◽  
J Andrews ◽  
R Laura
Keyword(s):  
Binding Sites ◽  
Serine Proteases ◽  
Enzyme Inhibitor ◽  
Molecular Model ◽  
Factor Xa ◽  
Affinity Labeling ◽  
Catalytic Center ◽  
Inhibitor Complex ◽  
Polypeptide Chains ◽  
Kinetics Of

We have determined that m-[o-(2-chloro-5-fluorosulfonylphenylureido)phenoxybutoxy]benza-midine [mCP(PBA)-F] is an affinity labeling reagent which labels both polypeptide chains of thrombin, factor Xa, complement component CIS and plasmin. As this means it is reacting outside of the catalytic center, we have called this reagent an exo-site affinity labeling reagent. Progressive irreversible inhibition of these enzymes by this reagent is rapid (k1st 2.5-4.6 x 10-3sec-1), the kinetics of inactivation are consistent with inhibition proceding via formation of a specific enzyme-inhibitor complex analogous to a Michaelis-Menton complex (KL - 115-26 μM), and diisopropylfluorophosphate or p-amidino-phenylmethanesulfonyfluoride Prevent labeling by [3H]mCP(PBA)-F. A molecular model of mCP(PBA)-F shows that the reactive SO2F group can be 17 A from the cationic amidine. The data are consistent with the hypothesis that both peptide chains are required for the specific proteolytic activity exhibited by these proteases and that the peptide chain which does not contain the active site serine is close to the catalytic center. (Supported by NIH and AHA grants

scholarly journals Monoclonal antibodies directed against mammalian RNA polymerase I. Identification of the catalytic center.

1983 ◽  
Vol 258 (21) ◽  
pp. 12976-12981 ◽  
Author(s):  
K M Rose ◽  
K A Maguire ◽  
J N Wurpel ◽  
D A Stetler ◽  
E D Márquez
Keyword(s):  
Monoclonal Antibodies ◽  
Rna Polymerase ◽  
Rna Polymerase I ◽  
Catalytic Center ◽  
Polymerase I

scholarly journals The Role of Arg13 in Protein Phosphatase M tPphA from Thermosynechococcus elongatus

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jiyong Su ◽  
Karl Forchhammer
Keyword(s):  
Amino Acid ◽  
Protein Phosphatase ◽  
Arginine Residue ◽  
Side Chain ◽  
Wild Type ◽  
Catalytic Center ◽  
Nitrophenyl Phosphate ◽  
Reduced Activity ◽  
Amino Acid Variants

A highly conserved arginine residue is close to the catalytic center of PPM/PP2C-type protein phosphatases. Different crystal structures of PPM/PP2C homologues revealed that the guanidinium side chain of this arginine residue can adopt variable conformations and may bind ligands, suggesting an important role of this residue during catalysis. In this paper, we randomly mutated Arginine 13 of tPphA, a PPM/PP2C-type phosphatase from Thermosynechococcus elongatus, and obtained 18 different amino acid variants. The generated variants were tested towards p-nitrophenyl phosphate and various phosphopeptides. Towards p-nitrophenyl phosphate as substrate, twelve variants showed 3–7 times higher Km values than wild-type tPphA and four variants (R13D, R13F, R13L, and R13W) completely lost activity. Strikingly, these variants were still able to dephosphorylate phosphopeptides, although with strongly reduced activity. The specific inability of some Arg-13 variants to hydrolyze p-nitrophenyl phosphate highlights the importance of additional substrate interactions apart from the substrate phosphate for catalysis. The properties of the R13 variants indicate that this residue assists in substrate binding.

Peroxidase and Toluidine Blue-Incorporated DNA Bio-Polyion Complex Film as Biosensing Layer for Hydrogen Peroxide Determination

2013 ◽  
Vol 750 ◽  
pp. 84-87 ◽  
Author(s):  
Ting Ting Gu ◽  
Hong Qi Xia ◽  
Jian Li Wang ◽  
Da Wei Yang ◽  
Yang Zhao ◽  
...  
Keyword(s):  
Toluidine Blue ◽  
Cathodic Current ◽  
Catalytic Center ◽  
Polyion Complex ◽  
Double Stranded Dna ◽  
Electron Transfer Rate Constant ◽  
Complex Membrane ◽  
Highly Sensitive ◽  
Electrochemical Redox ◽  
Complex Film

Horseradish peroxidase (HRP) and toluidine blue (TB) were incorporated in polyion complex membrane composed of double stranded DNA(dsDNA) and chitosan prepared on the surface of an glassy carbon (GC) disk electrode to fabricate highly sensitive and selective reagentless H2O2 biosensor. The embedded-TB in the DNA/chitosan membrane exhibited excellent electrochemical redox property with an electron transfer rate constant of 3.12 ± 0.5 sec−1, and shuttled electron effectively from the base GC electrode to catalytic center of the HRP. Under the applied potential of -0.22V (versus Ag/AgCl) and pH 7.0, the resulting electrode (HRP/DNA–TB/chitosan/GCE) exhibited rapid (<10 s) and sensitive response to H2O2. The calibration curve of H2O2, plotting steady-state cathodic current versus H2O2 concentration, was linear up to 0.1mM with a detection limit of 1 μM H2O2 (S/N = 3). The H2O2 response was scarcely interfered by ascorbic acid and uric acid, which potentially reduce oxidized intermediate of the HRP and interfere with the response of peroxidase-based electrodes.

scholarly journals Albumin nanoparticles loaded with hemin as peroxidase mimics for immunoassay

2021 ◽  
Author(s):  
Pavel Khramtsov ◽  
Maria Bochkova ◽  
Valeria Timganova ◽  
Dmitriy Kiselkov ◽  
Svetlana Zamorina ◽  
...  
Keyword(s):  
Colloidal Stability ◽  
Lower Cost ◽  
Clinical Diagnostics ◽  
Antibody Detection ◽  
Post Vaccination ◽  
Catalytic Center ◽  
Albumin Nanoparticles ◽  
Peroxidase Mimics ◽  
Colorimetric Immunoassay ◽  
Tetanus Antibodies

Contemporary immunoassays commonly used in clinical diagnostics mostly utilize enzymes, such as horseradish peroxidase, for signal generation. Numerous research is dedicated to the development of artificial peroxidase-mimicking catalysts with lower cost, high activity, better operational stability, and tunable properties. Herein we synthesized hemin-loaded bovine serum albumin (BSA) nanoparticles and applied them as catalytic labels (nanozymes) in colorimetric immunoassay of anti-tetanus antibodies. Hemin is a key part of the peroxidase catalytic center, possessing peroxidase like-activity. Albumin nanoparticles were loaded with multiple hemin molecules and decorated with Streptococcal protein G. Resulting nanozymes possessed good colloidal stability and allowed for antibody detection in blood serum. The sensitivity of antibody detection was sufficient for the assessment of post-vaccination immunity.

scholarly journals Insights into the functional architecture of the catalytic center of a maize β-glucosidase Zm-p60.1

2002 ◽  
Vol 58 (s1) ◽  
pp. c106-c106
Author(s):  
J. Marek ◽  
J. Zouhar ◽  
J. Vevodova ◽  
J. Damborsky ◽  
X.-D. Su ◽  
...  
Keyword(s):  
Functional Architecture ◽  
Catalytic Center

scholarly journals Ursolic Acid Targets Glucosyltransferase and Inhibits Its Activity to Prevent Streptococcus mutans Biofilm Formation

2021 ◽  
Vol 12 ◽  
Author(s):  
Yucui Liu ◽  
Yanxin Huang ◽  
Cong Fan ◽  
Zhongmei Chi ◽  
Miao Bai ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Ursolic Acid ◽  
Biofilm Formation ◽  
Natural Compound ◽  
Structural Integrity ◽  
Site Directed Mutagenesis ◽  
Extracellular Polysaccharides ◽  
Virulence Determinants ◽  
Pentacyclic Triterpene ◽  
Catalytic Center

Streptococcus mutans (S. mutans), the prime pathogen of dental caries, can secrete glucosyltransferases (GTFs) to synthesize extracellular polysaccharides (EPSs), which are the virulence determinants of cariogenic biofilms. Ursolic acid, a type of pentacyclic triterpene natural compound, has shown potential antibiofilm effects on S. mutans. To investigate the mechanisms of ursolic acid-mediated inhibition of S. mutans biofilm formation, we first demonstrated that ursolic acid could decrease the viability and structural integrity of biofilms, as evidenced by XTT, crystal violet, and live/dead staining assays. Then, we further revealed that ursolic acid could compete with the inherent substrate to occupy the catalytic center of GTFs to inhibit EPS formation, and this was confirmed by GTF activity assays, computer simulations, site-directed mutagenesis, and capillary electrophoresis (CE). In conclusion, ursolic acid can decrease bacterial viability and prevent S. mutans biofilm formation by binding and inhibiting the activity of GTFs.

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