Search results for "Isoelectric Point"

A simple method to estimate the isoelectric point of modified Tomato bushy stunt virus (TBSV) particles

2017

We present a simple method to estimate the isoelectric point (pI) of Tomato Bushy Stunt particles. We demonstrate that the combination of agarose gels with different pH buffers can be used to electrophorese the virus particles and their migration patterns can be compared. This method allows us to estimate the pI of the virus particles (wild type, wt, and genetically modified particles) and to monitor the effect of the pI of modified peptide side chains of the viral capsid subunit on the pI of the whole virus particle.

The Galactose-Specific Lectin from the Sponge Chondrilla Nucula Displays Anti-Human Immunodeficiency Virus Activity in vitro via Stimulation of the (…

1990

A new lectin has been isolated from the sponge Chondrilla nucula. The purified CN lectin is a protein composed of four polypeptide chains with a molecular weight (MW) of 15600. The isoelectric point is 4.5 and the amino acid composition is rich in aspartic and glutamic acid. The lectin precipitates erythrocytes from humans (A, B, O) with a titre between 25 and 210. The CN lectin is d-galactose-specific and displays a moderate mitogenic effect on spleen lymphocytes from mice and on CD4-positive human H9 cells. An interesting feature of this lectin is its ability to stimulate the (2′-5′)oligoriboadenylate [(2′-5′)A] metabolic pathway in non-infected and human immunodeficiency virus (HIV-1)-i…

Analysis of tear proteins by one- and two-dimensional thin-layer iosoelectric focusing, sodium dodecyl sulfate electrophoresis and lectin blotting. D…

1998

· Background: Isoelectric focusing (IEF) of tear proteins has not yet been carried out in a satisfactory way. Two-dimensional (2D) electrophoresis, especially in the combination of IEF with SDS, is able to differentiate between proteins in detail. The purpose of this study was therefore to analyze tear proteins by 1D IEF alone and in combination with a 2D pattern, and by IEF followed by lectin staining. · Methods: Ampholines, covering a broad range from pH 3 to pH 10, were applied. After IEF, semi-dry blotting and incubation with a group II lectin and two group V lectins was performed. · Results: Tear proteins could be separated into 31 single bands. Tear-specific pre-albumin (TSPA), lactof…

Human liver cytosolic epoxide hydrolases.

1988

Human liver epoxide hydrolases were characterized by several criteria and a cytosolic cis-stilbene oxide hydrolase (cEHcso) was purified to apparent homogeneity. Styrene oxide and five phenylmethyloxiranes were tested as substrates for human liver epoxide hydrolases. With microsomes activity was highest with trans-2-methylstyrene oxide, followed by styrene 7, 8-oxide, cis-2-With methylstyrene oxide, cis-1,2-dimethylstyrene oxide, trans-1, 2-dimethylstyrene oxide and 2, 2-dimethylstyrene oxide. With cytosol the same order was obtained for the first three substrates, whereas activity with 2, 2-dimethylstyrene oxide was higher than with cis-1,2-dimethylstyrene oxide and no hydrolysis occurred …

Halloysite/Keratin Nanocomposite for Human Hair Photoprotection Coating

2020

We propose a novel keratin treatment of human hair by its aqueous mixtures with natural halloysite clay nanotubes. The loaded clay nanotubes together with free keratin produce micrometer-thick protective coating on hair. First, colloidal and structural properties of halloysite/keratin dispersions and the nanotube loaded with this protein were investigated. Above the keratin isoelectric point (pH = 4), the protein adsorption into the positive halloysite lumen is favored because of the electrostatic attractions. The ζ-potential magnitude of these core-shell particles increased from -35 (in pristine form) to -43 mV allowing for an enhanced colloidal stability (15 h at pH = 6). This keratin-cla…

Comparative analysis of the electrostatics of the binding of cationic proteins to vesicles: Asymmetric location of anionic phospholipids

2009

The role of electrostatics is studied in the adsorption of cationic proteins to zwitterionic phosphatidylcholine (PC) and anionic PC/phosphatidylglycerol (PG) mixed small unilamellarvesicles (SUVs). For model proteins the interaction is monitored vs. PG content at low ionic strength. The adsorption of lysozyme and myoglobin (isoelectric point, pl 7-11) is investigated in SUVs, along with changes of the fluorescence emission spectra of the cationic proteins, via their adsorption on SUVs. In the Gouy-Chapman formalism, the activity coefficient goes with the square of charge number. Deviations from the ideal model could indicate the asymmetric location of the anionic phospholipid in the bilaye…

Electrostatics regulate Epigallocatechin-Gallate effects on Bovine Serum Albumin aggregation

Protein aggregation processes are complex phenomena often involved in the etiology of several pathologies. It is now assessed that all proteins, in suitable conditions, may undergo supramolecular assembly. Aggregation pathways are known to be controlled by solution conditions which regulate protein-protein and protein-solvent interactions affecting binding mechanisms, morphology and inherent toxicity of the aggregate species. In this context, the presence of small molecules was indicated as a promising method to modulate protein-protein interactions reducing pathogenic aggregation. In the light of the idea that common mechanisms regulate anti-aggregogenic properties of small molecules, we h…

A new form of tumor and fetal collagen that binds laminin.

1993

Human breast and colon carcinoma tissues contain a form of collagen, not described before, composed of alpha 1 chains of similar size (approximately 100 kDa) but different charge. The three constitutive chains, separated by two-dimensional electrophoresis, are a unique acidic component, undetectable in other collagen types, with an apparent isoelectric point of 4-5, and two more basic components displaying the same electrophoretic behavior as alpha 1(III) and alpha 1(I), respectively. The acidic chain is structurally distinct from alpha 1(I) and displays a cyanogen bromide-derived fragment of similar size to CB5(III). This collagen in its native state is resistant to trypsin and metalloprot…

Improving Fractionation of Human Milk Proteins through Calcium Phosphate Coprecipitation and Their Rapid Characterization by Capillary Electrophoresis

2018

This work describes a simple sample pretreatment method for the fractionation of human milk proteins (into their two main groups, whey and caseins) prior to their analysis. The protein-extraction protocol is based on the addition of calcium phosphate to nonadjusted pH human milk. The combination of calcium ions with phosphate results in an effective coprecipitation of caseins. To assess the suitability of this fractionation protocol, the protein extracts were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), LC-MS/MS, and capillary electrophoresis (CE) analysis. The results evidence a significant decrease in contamination of casein fraction with whey proteins…

Species-Specific Aggregation Factor in Sponges

1978

An aggregation factor (AF) from the siliceous sponge Suberites domuncula has been isolated and purified by the following steps: Sepharose 2 B gel chromatography, sucrose gradient, Nonidet treatment, Sephadex G-100 gel chromatography and DEAE-Sephadex ion-exchange chromatography. By this procedure the AF was purified 1340-fold with a 63% yield nearly to homogeneity. The AF is originally associated with large particles, characterized by a sedimentation of 2200 S. These particles have been visualized electron microscopically; they are characterized by a filament-like shape of a length of 3400 A and a cross-sectional diameter of 230 A. The purified, low-molecular weight AF has a buoyant density…