Covalently immobilized catalase on functionalized graphene: effect on the activity, immobilization efficiency, and tetramer stability

2018 ◽  
Vol 6 (12) ◽  
pp. 3231-3240 ◽  
Author(s):  
Davide Barreca ◽  
Giulia Neri ◽  
Angela Scala ◽  
Enza Fazio ◽  
Davide Gentile ◽  
...  
Keyword(s):  
Biological Properties ◽  
Functionalized Graphene ◽  
Immobilized Catalase ◽  
Quaternary Structures ◽  
Covalently Linked ◽  
Tetramer Stability

The different anchorage modes of catalase covalently linked to graphene affect the secondary and quaternary structures determining the biological properties.

scholarly journals Shedding Light on the Chemistry and the Properties of Münchnone Functionalized Graphene

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1629
Author(s):  
Giulia Neri ◽  
Enza Fazio ◽  
Antonia Nostro ◽  
Placido Giuseppe Mineo ◽  
Angela Scala ◽  
...  
Keyword(s):  
Density Functional ◽  
Antimicrobial Properties ◽  
Biological Properties ◽  
Azomethine Ylide ◽  
Functionalized Graphene ◽  
Functional Theory ◽  
Pyrrole Derivatives ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Direct Functionalization

Münchnones are mesoionic oxazolium 5-oxides with azomethine ylide characteristics that provide pyrrole derivatives by a 1,3-dipolar cycloaddition (1,3-DC) reaction with acetylenic dipolarophiles. Their reactivity was widely exploited for the synthesis of small molecules, but it was not yet investigated for the functionalization of graphene-based materials. Herein, we report our results on the preparation of münchnone functionalized graphene via cycloaddition reactions, followed by the spontaneous loss of carbon dioxide and its further chemical modification to silver/nisin nanocomposites to confer biological properties. A direct functionalization of graphite flakes into few-layers graphene decorated with pyrrole rings on the layer edge was achieved. The success of functionalization was confirmed by micro-Raman and X-ray photoelectron spectroscopies, scanning transmission electron microscopy, and thermogravimetric analysis. The 1,3-DC reactions of münchnone dipole with graphene have been investigated using density functional theory to model graphene. Finally, we explored the reactivity and the processability of münchnone functionalized graphene to produce enriched nano biomaterials endowed with antimicrobial properties.

Silica nanoparticles functionalized with porphyrins and analogs for biomedical studies

2011 ◽  
Vol 15 (07n08) ◽  
pp. 517-533 ◽  
Author(s):  
Flávio Figueira ◽  
José A.S. Cavaleiro ◽  
João P.C. Tomé
Keyword(s):  
Photodynamic Therapy ◽  
Silica Nanoparticles ◽  
Biological Properties ◽  
Environmental Applications ◽  
Target Cells ◽  
Covalently Linked ◽  
The Times ◽  
Related Compounds

This review focus on the preparation of silica nanoparticles functionalized with porphyrins and related compounds. It is aimed to highlight their features as photosensitizers in the area of photodynamic therapy. In this field, photosensitizers have been covalently and non-covalently linked to silica nanoparticles, in order to study their photophysical and biological properties. Another fascinating scenario for photosensitizer-silica nanoparticles hybrids involves the possibility of including metal cores for conditioning the uptake in the target cells, allowing most of the times the combination of therapies and in certain conditions to facilitate the removal and reutilization of the photosensitizer in environmental applications.

scholarly journals Biogenesis, functions and clinical significance of circRNAs in gastric cancer

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Chan Shan ◽  
Yinfeng Zhang ◽  
Xiaodan Hao ◽  
Jinning Gao ◽  
Xinzhe Chen ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Molecular Mechanisms ◽  
Disease Diagnosis ◽  
Biological Properties ◽  
Circular Rnas ◽  
High Morbidity ◽  
Malignant Tumours ◽  
Diagnosis And Prognosis ◽  
Covalently Linked ◽  
New Biomarkers

Abstract Gastric cancer (GC) is one of the most common malignant tumours in the world and has high morbidity and mortality. Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently linked circular structures. In recent years, plentiful circRNAs have been discovered that participate in many biological processes, including the initiation and development of tumours. Increasing evidences suggest important biological functions of circRNAs, implying that circRNAs may serve as vital new biomarkers and targets for disease diagnosis and prognosis. Among these, circRNAs are tend to aberrantly expressed and are regarded as potential biomarkers in the carcinogenesis and progression of GC. This review systematically summarised the biogenesis, biological properties and functions of circRNAs, with a focus on their relationship with GC, as well as their probable clinical implications on GC. As our cognition of the relation between circRNAs and GC deepens, more molecular mechanisms of GC progression will be discovered, and new therapeutic strategies will be used for the prevention and treatment of GC.

scholarly journals Evidence concerning the mechanism of insulin-receptor interaction and the structure of the insulin receptor from biological properties of covalently linked insulin dimers

1983 ◽  
Vol 216 (3) ◽  
pp. 687-694 ◽  
Author(s):  
M A Tatnell ◽  
R H Jones ◽  
K P Willey ◽  
A Schüttler ◽  
D Brandenburg
Keyword(s):  
Insulin Receptor ◽  
Plasma Membranes ◽  
Gel Filtration ◽  
Biological Properties ◽  
Receptor Interaction ◽  
Cross Linking ◽  
Receptor Complex ◽  
Biological Responses ◽  
Rat Liver Plasma Membranes ◽  
Covalently Linked

Covalently linked insulin dimers have been prepared by cross-linking two insulin monomers with a flexible suberoyl chain at either the B1 phenylalanine or the B29 lysine residue. Binding potencies of dimers determined by inhibition of binding of 125I-insulin to isolated rat liver plasma membranes or adipocytes were 2.5-7-fold greater than their abilities to stimulate lipogenesis in adipocytes. Rates of liver plasma-membrane-associated degradation of labelled insulin and dimers, measured by gel filtration, were similar at 37 degrees C. Binding and lipogenesis potencies of dimers prepared by substitution of each monomeric half of an asymmetrical dimer with desoctapeptide insulin, an almost inactive derivative, implicated the B1-cross-linked monomeric half as predominantly interacting with the insulin receptor. These results suggest that (1) dimers bind univalently to a bivalent insulin-receptor complex, in which the two individual binding subunits are arranged with anti-parallel symmetry and (2) the mechanism by which insulin binds and initiates its biological responses requires a conformational change within the insulin-receptor complex and/or in the insulin molecule for full biological expression.

Three Dimensional structure and organization of diploid chromosomes by optical section microscopy

1987 ◽  
Vol 45 ◽  
pp. 633-635
Author(s):  
David A. Agard ◽  
Yasushi Hiraoka ◽  
John W. Sedat
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Developmental State ◽  
Mitotic Cell ◽  
Biological Properties ◽  
Dimensional Structure ◽  
Specific Gene ◽  
Three Dimensional Structure ◽  
Complementary Techniques ◽  
Dynamic Structures

In an effort to understand the complex relationship between structure and biological function within the nucleus, we have embarked on a program to examine the three-dimensional structure and organization of Drosophila melanogaster embryonic chromosomes. Our overall goal is to determine how DNA and proteins are organized into complex and highly dynamic structures (chromosomes) and how these chromosomes are arranged in three dimensional space within the cell nucleus. Futher, we hope to be able to correlate structual data with such fundamental biological properties as stage in the mitotic cell cycle, developmental state and transcription at specific gene loci.Towards this end, we have been developing methodologies for the three-dimensional analysis of non-crystalline biological specimens using optical and electron microscopy. We feel that the combination of these two complementary techniques allows an unprecedented look at the structural organization of cellular components ranging in size from 100A to 100 microns.

Large-cluster and combined fluorescent and gold immunoprobes

1996 ◽  
Vol 54 ◽  
pp. 892-893
Author(s):  
Richard D. Powell ◽  
James F. Hainfeld ◽  
Carol M. R. Halsey ◽  
David L. Spector ◽  
Shelley Kaurin ◽  
...  
Keyword(s):  
Metal Cluster ◽  
Sulfonyl Chloride ◽  
Gel Filtration ◽  
Cross Linking ◽  
Site Specific ◽  
Fab Fragments ◽  
Cluster Label ◽  
Covalently Linked ◽  
Texas Red ◽  
Fold Excess

Two new types of covalently linked, site-specific immunoprobes have been prepared using metal cluster labels, and used to stain components of cells. Combined fluorescein and 1.4 nm “Nanogold” labels were prepared by using the fluorescein-conjugated tris (aryl) phosphine ligand and the amino-substituted ligand in the synthesis of the Nanogold cluster. This cluster label was activated by reaction with a 60-fold excess of (sulfo-Succinimidyl-4-N-maleiniido-cyclohexane-l-carboxylate (sulfo-SMCC) at pH 7.5, separated from excess cross-linking reagent by gel filtration, and mixed in ten-fold excess with Goat Fab’ fragments against mouse IgG (obtained by reduction of F(ab’)2 fragments with 50 mM mercaptoethylamine hydrochloride). Labeled Fab’ fragments were isolated by gel filtration HPLC (Superose-12, Pharmacia). A combined Nanogold and Texas Red label was also prepared, using a Nanogold cluster derivatized with both and its protected analog: the cluster was reacted with an eight-fold excess of Texas Red sulfonyl chloride at pH 9.0, separated from excess Texas Red by gel filtration, then deprotected with HC1 in methanol to yield the amino-substituted label.

In vitro assembly of 2-D crystals from partially purified EA1 protein secreted by Bacillus anthracis strain Delta Sterne-1

1994 ◽  
Vol 52 ◽  
pp. 276-277
Author(s):  
Mary Beth Downs ◽  
Wilson Ribot ◽  
Joseph W. Farchaus
Keyword(s):  
Cell Wall ◽  
Molecular Sieves ◽  
Cell Envelope ◽  
Single Species ◽  
Supporting Cell ◽  
Surface Layers ◽  
Rabbit Igg ◽  
In Vitro Assembly ◽  
Covalently Linked

Many bacteria possess surface layers (S-layers) that consist of a two-dimensional protein lattice external to the cell envelope. These S-layer arrays are usually composed of a single species of protein or glycoprotein and are not covalently linked to the underlying cell wall. When removed from the cell, S-layer proteins often reassemble into a lattice identical to that found on the cell, even without supporting cell wall fragments. S-layers exist at the interface between the cell and its environment and probably serve as molecular sieves that exclude destructive macromolecules while allowing passage of small nutrients and secreted proteins. Some S-layers are refractory to ingestion by macrophages and, generally, bacteria are more virulent when S-layers are present.When grown in rich medium under aerobic conditions, B. anthracis strain Delta Sterne-1 secretes large amounts of a proteinaceous extractable antigen 1 (EA1) into the growth medium. Immunocytochemistry with rabbit polyclonal anti-EAl antibody made against the secreted protein and gold-conjugated goat anti-rabbit IgG showed that EAI was localized at the cell surface (fig 1), which suggests its role as an S-layer protein.

Structure of rattlesnake venom lectin determined by single particle high-resolution electron microscopy

1996 ◽  
Vol 54 ◽  
pp. 62-63
Author(s):  
Peter D. Moisiuk ◽  
Daniel R. Beniac ◽  
Ross A. Ridsdale ◽  
Martin Young ◽  
Bhushan Nagar ◽  
...  
Keyword(s):  
High Resolution Electron Microscopy ◽  
Lipid Monolayer ◽  
Outer Diameter ◽  
X Ray Diffraction ◽  
Single Particles ◽  
Crotalus Atrox ◽  
3D Reconstructions ◽  
X Ray ◽  
Rattlesnake Venom ◽  
Covalently Linked

Venom from the rattlesnake Crotalus atrox contains a mixture of enzymes that induce a localized effect leading to hemorrhaging, necrosis and edema. As a member of the crotalid family of snake venoms, Crotalus atrox venom contains a C-type lectin that will agglutinate blood cells in a Ca2+-dependent fashion. The lectin is a hydrophilic protein, consisting of two covalently linked, 135 amino acid residues, identical subunits that are rich in aspartic acid, glutamic acid and lysine. Sequence homology with known carbohydrate recognition domains (CRDs) indicates that rattlesnake venom lectin (RSLV) contains a CRD motif that is not linked to accessory domains. Preliminary X-ray diffraction and sedimentation analysis has indicated that lectin from Crotalus atrox forms decamers composed of two five-fold symmetric pentamers. Single particles of RSVL imaged at – 171°C displayed two distinct orientations on the specimen support (Figure a) following incubation in a crystallization Teflon well, coated with a lipid monolayer consisting of phosphatidylcholine and monosialoganglioside. When lying in an end-on orientation, the lectin exhibited a “pentagonal ring” with an outer diameter of 6.7 nm and an inner hollow core of 1.7 nm. A side orientation was also seen, whereby a thickness of 5.8 nm was measured for the lectin. Image processing of 2280 single particles placed in 100 classes (Figure b) led to 3D reconstructions of RSVL (Figure c). Density limited 3D reconstructions showed the lectin to be made of two five-fold symmetrical rings covalently linked between the five subunits that constitute each ring of this homodimer. These results are consistent with sedimentation and preliminary X-ray diffraction analysis on the shape of RSVL and provide the framework for structural verification by 2D electron crystallography.

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