scholarly journals Synthesis of a Porous C3N-Derived Framework with High Yield by Gallic Acid Cross-Linking Using Salt Melts

2020 ◽  
Vol 12 (11) ◽  
pp. 13127-13133 ◽  
Author(s):  
Zhihong Tian ◽  
Tobias Heil ◽  
Johannes Schmidt ◽  
Shaokui Cao ◽  
Markus Antonietti
Keyword(s):  
Gallic Acid ◽  
High Yield ◽  
Cross Linking ◽  
Salt Melts

scholarly journals Organization of FliN Subunits in the Flagellar Motor of Escherichia coli

2006 ◽  
Vol 188 (7) ◽  
pp. 2502-2511 ◽  
Author(s):  
Koushik Paul ◽  
David F. Blair
Keyword(s):  
Thermotoga Maritima ◽  
High Yield ◽  
Major Constituent ◽  
Cross Linking ◽  
Flagellar Motor ◽  
Electron Microscopic ◽  
Close Match ◽  
Terminal Domain ◽  
Equilibrium Sedimentation ◽  
Flagellar Assembly

ABSTRACT FliN is a major constituent of the C ring in the flagellar basal body of many bacteria. It is present in >100 copies per flagellum and together with FliM and FliG forms the switch complex that functions in flagellar assembly, rotation, and clockwise-counterclockwise switching. FliN is essential for flagellar assembly and switching, but its precise functions are unknown. The C-terminal part of the protein is best conserved and most important for function; a crystal structure of this C-terminal domain of FliN from Thermotoga maritima revealed a saddle-shaped dimer formed mainly from β strands (P. N. Brown, M. A. A. Mathews, L. A. Joss, C. P. Hill, and D. F. Blair, J. Bacteriol. 187:2890-2902, 2005). Equilibrium sedimentation studies showed that FliN can form stable tetramers and that a FliM1FliN4 complex is also stable. Here, we have examined the organization of FliN subunits by using targeted cross-linking. Cys residues were introduced at various positions in FliN, singly or in pairs, and disulfide cross-linking was induced by oxidation. Efficient cross-linking was observed for certain positions near the ends of the dimer and for some positions in the structurally uncharacterized N-terminal domain. Certain combinations of two Cys replacements gave a high yield of cross-linked tetramer. The results support a model in which FliN is organized in doughnut-shaped tetramers, stabilized in part by contacts involving the N-terminal domain. Electron microscopic reconstructions show a bulge at the bottom of the C-ring whose size and shape are a close match for the hypothesized FliN tetramer.

scholarly journals Conjugation of horseradish peroxidase to staphylococcal protein A with benzoquinone, glutaraldehyde, or periodate as cross-linking reagents.

1981 ◽  
Vol 29 (2) ◽  
pp. 266-270 ◽  
Author(s):  
H Nygren ◽  
H A Hansson
Keyword(s):  
Horseradish Peroxidase ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Protein A ◽  
Molecular Size ◽  
High Yield ◽  
Second Step ◽  
Cross Linking ◽  
Staphylococcal Protein A ◽  
Staphylococcal Protein

Horseradish peroxidase was conjugated to Staphylococcal protein A by three different two-step procedures using an increasing excess of peroxidase in the second step reaction. The yield of conjugated protein A was analyzed by SDS-polyacrylamide gel electrophoresis. Conjugation of peroxidase to protein A with benzoquinone or glutaraldehyde as cross-linking reagents at a 3- to 4-fold molar excess of peroxidase resulted in a high yield of coupled protein A with conjugates of low molecular size. Conjugation of peroxidase to protein A by the periodate method resulted in a high yield of coupled protein A with polymeric conjugates of large molecular size. Based on these results, conjugates produced with glutaraldehyde as cross-linking reagents were further analyzed. The capacity of the conjugates to precipitate human immunoglobulin evaluated by radial immunodiffusion was found to be reduced to about 50% of that of native protein A. Conjugates produced with glutaraldehyde as cross-linking reagent retained 70% of the enzyme activity of native peroxidase.

scholarly journals FliG Subunit Arrangement in the Flagellar Rotor Probed by Targeted Cross-Linking

2005 ◽  
Vol 187 (16) ◽  
pp. 5640-5647 ◽  
Author(s):  
Bryan J. Lowder ◽  
Mark D. Duyvesteyn ◽  
David F. Blair
Keyword(s):  
High Yield ◽  
Cross Linking ◽  
Amino Acid Residues ◽  
Electron Microscopic ◽  
Bacterial Flagellum ◽  
Terminal Domain ◽  
Complex Protein ◽  
Microscopic Studies ◽  
Discrete Domains ◽  
Α Helix

ABSTRACT FliG is a component of the switch complex on the rotor of the bacterial flagellum. Each flagellar motor contains about 25 FliG molecules. The protein of Escherichia coli has 331 amino acid residues and comprises at least two discrete domains. A C-terminal domain of about 100 residues functions in rotation and includes charged residues that interact with the stator protein MotA. Other parts of the FliG protein are essential for flagellar assembly and interact with the MS ring protein FliF and the switch complex protein FliM. The crystal structure of the middle and C-terminal parts of FliG shows two globular domains joined by an α-helix and a short extended segment that contains two well-conserved glycine residues. Here, we describe targeted cross-linking studies of FliG that reveal features of its organization in the flagellum. Cys residues were introduced at various positions, singly or in pairs, and cross-linking by a maleimide or disulfide-inducing oxidant was examined. FliG molecules with pairs of Cys residues at certain positions in the middle domain formed disulfide-linked dimers and larger multimers with a high yield, showing that the middle domains of adjacent subunits are in fairly close proximity and putting constraints on the relative orientation of the domains. Certain proteins with single Cys replacements in the C-terminal domain formed dimers with moderate yields but not larger multimers. On the basis of the cross-linking results and the data available from mutational and electron microscopic studies, we propose a model for the organization of FliG subunits in the flagellum.

scholarly journals Fluidity of Structure and Swiveling of Helices in the Subunit c Ring of Escherichia coli ATP Synthase as Revealed by Cysteine-Cysteine Cross-Linking

2007 ◽  
Vol 282 (46) ◽  
pp. 33788-33794 ◽  
Author(s):  
Owen D. Vincent ◽  
Brian E. Schwem ◽  
P. Ryan Steed ◽  
Warren Jiang ◽  
Robert H. Fillingame
Keyword(s):  
Escherichia Coli ◽  
Atp Synthase ◽  
Time Course ◽  
Structural Model ◽  
Ring Structure ◽  
High Yield ◽  
Cross Linking ◽  
E Coli ◽  
The Cross ◽  
Ilyobacter Tartaricus

Subunit c in the membrane-traversing F0 sector of Escherichia coli ATP synthase is known to fold with two transmembrane helices and form an oligomeric ring of 10 or more subunits in the membrane. Models for the E. coli ring structure have been proposed based upon NMR solution structures and intersubunit cross-linking of Cys residues in the membrane. The E. coli models differ from the recent x-ray diffraction structure of the isolated Ilyobacter tartaricus c-ring. Furthermore, key cross-linking results supporting the E. coli model prove to be incompatible with the I. tartaricus structure. To test the applicability of the I. tartaricus model to the E. coli c-ring, we compared the cross-linking of a pair of doubly Cys substituted c-subunits, each of which was compatible with one model but not the other. The key finding of this study is that both A21C/M65C and A21C/I66C doubly substituted c-subunits form high yield oligomeric structures, c2, c3... c10, via intersubunit disulfide bond formation. The results indicate that helical swiveling, with resultant interconversion of the two conformers predicted by the E. coli and I. tartaricus models, must be occurring over the time course of the cross-linking experiment. In the additional experiments reported here, we tried to ascertain the preferred conformation in the membrane to help define the most likely structural model. We conclude that both structures must be able to form in the membrane, but that the helical swiveling that promotes their interconversion may not be necessary during rotary function.

Preparation of Genipin by Hydrolysis of Geniposide with Co-Immobilized Enzyme

2011 ◽  
Vol 236-238 ◽  
pp. 1793-1798 ◽  
Author(s):  
Hua Zheng Liang ◽  
He Chen ◽  
Jian Feng Wang ◽  
Yu Lan He
Keyword(s):  
High Performance ◽  
Immobilized Enzyme ◽  
Low Cost ◽  
Enzymatic Properties ◽  
High Yield ◽  
Cross Linking ◽  
Optimum Temperature ◽  
Environmental Friendly ◽  
Optimum Ph ◽  
Hydrolysis Of

Co-immobilize enzyme by cross-linking and embedding, optimize conditions for immobilizing, determinate the enzymatic properties of co-immobilized enzyme and study the methods for preparation of genipin using co-immobilized enzyme to hydrolyze geniposide. Optimized immobilizing conditions include glutaraldehyde concentration being 0.15%, cross-linking temperature being 20°C, cross-linking time being 2 hours, the activity of co-immobilized β-glucosidase and cell reaches to 65.33U/mg and the enzyme activity recovery being 52.63%. Enzymatic properties of co-immobilized enzyme are following: optimum temperature is 55°C and optimum pH is 5.0. The transformation experiments are carried out with co-immobilized enzyme. The results show that half-life of co-immobilized enzyme reaches around 40 days, higher than the normal immobilized enzyme. The conversion rate of geniposide is above 95% after 8 hours. The genipin is isolated, purified and recrystallized to reach more than 98% of purity by High Performance Liquid Chromatography. Advantages to prepare genipin using co-immobilized enzyme include low cost, high yield, environmental friendly and easy to manufacturing.

High‐yield trapping of EGF‐induced receptor dimers by chemical cross‐linking 1

1989 ◽  
Vol 3 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Bradford O. Fanger ◽  
Judy E. Stephens ◽  
James V. Staros
Keyword(s):  
High Yield ◽  
Cross Linking ◽  
Receptor Dimers ◽  
Chemical Cross Linking

High Yield Polyborosilazane Precursor for SiBN Ceramics

2014 ◽  
Vol 1004-1005 ◽  
pp. 409-414 ◽  
Author(s):  
Shuai Yong Jin ◽  
Kang Kang Guo ◽  
Hui Min Qi ◽  
Ya Ping Zhu ◽  
Fan Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Yield ◽  
Cross Linking ◽  
Differential Scanning Calorimetric ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
X Ray Diffraction ◽  
Ceramic Yield ◽  
X Ray ◽  
Amorphous Structures

The processible and high yield polyborosilazane (PBSZ) precursor for SiBN ceramics was prepared by coammonolysis reaction of dichlorosilane and trichloroborazine. The synthesized PBSZ precursor was characterized by Fourier Transform Infrared spectroscopy (FTIR),1H,11B, and29Si Nuclear Magnetic Resonance (NMR), and its ceramic conversion chemistry was investigated by differential scanning calorimetric (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). The PBSZ precursor is a viscous liquid and changes to an insoluble solid via a cross-linking reaction between the N-H group and Si-H group as post-heated from 60 to 180°C. The insoluble solid is transformed to Si3N4and BN amorphous structures with an approximately 95% ceramic yield after being pyrolyzed to 1000°C.

scholarly journals In Vitro Assembly and Structure of Trichocyte Keratin Intermediate Filaments

2000 ◽  
Vol 151 (7) ◽  
pp. 1459-1468 ◽  
Author(s):  
He Wang ◽  
David A.D. Parry ◽  
Leslie N. Jones ◽  
William W. Idler ◽  
Lyuben N. Marekov ◽  
...  
Keyword(s):  
Intermediate Filaments ◽  
Disulfide Bonds ◽  
Cell Types ◽  
High Yield ◽  
Cross Linking ◽  
In Vitro Assembly ◽  
Type Ia ◽  
Molecular Alignments ◽  
The 1960S

Intermediate filaments (IF) have been recognized as ubiquitous components of the cytoskeletons of eukaryotic cells for 25 yr. Historically, the first IF proteins to be characterized were those from wool in the 1960s, when they were defined as low sulfur keratins derived from “microfibrils.” These proteins are now known as the type Ia/type IIa trichocyte keratins that constitute keratin IF of several hardened epithelial cell types. However, to date, of the entire class of >40 IF proteins, the trichocyte keratins remain the only ones for which efficient in vitro assembly remains unavailable. In this paper, we describe the assembly of expressed mouse type Ia and type IIa trichocyte keratins into IF in high yield. In cross-linking experiments, we document that the alignments of molecules within reduced trichocyte IF are the same as in type Ib/IIb cytokeratins. However, when oxidized in vitro, several intermolecular disulfide bonds form and the molecular alignments rearrange into the pattern shown earlier by x-ray diffraction analyses of intact wool. We suggest the realignments occur because the disulfide bonds confer substantially increased stability to trichocyte keratin IF. Our data suggest a novel role for disulfide bond cross linking in stabilization of these IF and the tissues containing them.

scholarly journals Basic density and pulp yield relationship with some chemical parameters in eucalyptus trees

2006 ◽  
Vol 41 (12) ◽  
pp. 1687-1691 ◽  
Author(s):  
Ana Maria Loureiro da Seca ◽  
Fernando Manoel de Jesus Domingues
Keyword(s):  
Gallic Acid ◽  
Group Analysis ◽  
Basic Density ◽  
Methoxyl Group ◽  
High Yield ◽  
Pulp Yield ◽  
Total Phenols ◽  
Chemical Parameters ◽  
Total Sugars ◽  
Frequency Distributions

The objective of this work was to evaluate the use of basic density and pulp yield correlations with some chemical parameters, in order to differentiate an homogeneous eucalyptus tree population, in terms of its potential for pulp production or some other technological applications. Basic density and kraft pulp yield were determined for 120 Eucalyptus globulus trees, and the values were plotted as frequency distributions. Homogenized samples from the first and fourth density quartiles and first and fourth yield quartiles were submitted to total phenols, total sugars and methoxyl group analysis. Syringyl/guaiacyl (S/G) and syringaldehyde/vanillin (S/V) ratios were determined on the kraft lignins from wood of the same quartiles. The results show the similarity between samples from high density and low yield quartiles, both with lower S/G (3.88-4.12) and S/V (3.99-4.09) ratios and higher total phenols (13.3-14.3 g gallic acid kg-1 ). Woods from the high yield quartile are statistically distinguished from all the others because of their higher S/G (5.15) and S/V (4.98) ratios and lower total phenols (8.7 g gallic acid kg-1 ). Methoxyl group and total sugars parameters are more adequate to distinguish wood samples with lower density.

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