Search results for "Isoelectric Point"
showing 10 items of 65 documents
Physicochemical characterization of the fifth (C5), sixth (C6), seventh (C7), eighth (C8) and ninth (C9) component of guinea pig complement.
1971
A physicochemical characterization of the purified guinea pig complement components C5 to C9 is given. For this purpose the sedimentation rate, the diffusion coefficient, the molecular weight and the isoelectric point were determined and compared with the values already known for the guinea pig and human complement system. For the determination of the physicochemical parameters gel filtration on Sephadex G-200, ultracentrifugation applying a sucrose density gradient and thin-layer isoelectric focusing were used. By comparing the values of the human and guinea pig complement a remarkable similarity is shown.
Proteomic analysis of the photosystem I light-harvesting antenna in tomato (Lycopersicon esculentum).
2004
Until now, more genes of the light-harvesting antenna of higher-plant photosystem I (PSI) than proteins have been described. To improve our understanding of the composition of light-harvesting complex I (LHCI) of tomato (Lycopersicon esculentum), we combined one- and two-dimensional (1-D and 2-D, respectively) gel electrophoresis with immunoblotting and tandem mass spectrometry (MS/ MS). Separation of PSI with high-resolution 1-D gels allowed separation of five bands attributed to proteins of LHCI. Immunoblotting with monospecific antibodies and MS/MS analysis enabled the correct assignment of the four prominent bands to light-harvesting proteins Lhcal -4. The fifth band was recognized by o…
Isolation and characterization of a 60-70-kD plasma membrane glycoprotein involved in the contact-dependent inhibition of growth
1990
Previous studies have shown that plasma membrane compounds are involved in the contact-dependent inhibition of growth of human diploid fibroblasts. The purification of the active plasma membrane glycoprotein is described in this report. The glycoprotein has an apparent molecular mass of 60-70 kD and, due to differential sialylation, isoelectric points between pH 5.5. and 6.2. Treatment with sialidase yielded one spot in two-dimensional gel electrophoresis with an isoelectric point of 6.3. After removal of the N-glycosidically linked oligosaccharide chains, the apparent molecular mass is reduced by approximately 22 kD. Treatment was diluted NaOH, which removes the O-glycosidically linked por…
Killer toxin of Hanseniaspora uvarum
1990
The yeast Hanseniaspora uvarum liberates a killer toxin lethal to sensitive strains of the species Saccharomyces cerevisiae. Secretion of this killer toxin was inhibited by tunicamycin, an inhibitor of N-glycosylation, although the mature killer protein did not show any detectable carbohydrate structures. Culture supernatants of the killer strain were concentrated by ultrafiltration and the extracellular killer toxin was precipitated with ethanol and purified by ion exchange chromatography. SDS-PAGE of the electrophoretically homogenous killer protein indicated an apparent molecular mass of 18,000. Additional investigations of the primary toxin binding sites within the cell wall of sensitiv…
Rat and human liver cytosolic epoxide hydrolases: evidence for multiple forms at level of protein and mRNA.
1990
Two forms of human liver cytosolic epoxide hydrolase (cEH) with diagnostic substrate specificity for trans-stilbene oxide (cEHTSO) and cis-stilbene oxide (cEHCSO) have been identified, and cEHCSO was purified to apparent homogeneity. The enzyme had a monomer molecular weight of 49 kDa and an isoelectric point of 9.2. Pure cEHCSO hydrolyzed CSO at a rate of 145 nmole/min/mg. TSO was not metabolized at a detectable level, and like cEHTSO, the enzyme was about three times more active at pH 7.4 than at pH 9.0. Unlike cEHTSO, cEHCSO was efficiently inhibited by 1 mM 1-trichloropropene oxide (90.5%) and 1 mM STO (92%). Similarly, liver cEH purified 541-fold from fenofibrate induced Fischer 344 ra…
A novel galactose- and arabinose-specific lectin from the sponge Pellina semitubulosa: isolation, characterization and immunobiological properties.
1992
A new lectin from the sponge Pellina semitubulosa is derived which was extracted and purified to homogeneity. The purified lectin is probably a hexamer of polypeptide chains (each M(r) 34,000) which are covalently linked via disulfide linkages; the isoelectric point is 6.1. The lectin displays the following specificities: D-galactose (50% inhibition of hemagglutination at 0.2 mM) = L-arabinose (0.2 mM) greater than D-fucose (1.5 mM) greater than D-glucose (3.0 mM). It precipitates human erythrocytes (A1, A2, A1B, B, and O) with a titer between 2(8) and 2(11) and erythrocytes from sheep and rabbits with a titer between 2(5) and 2(10). The Pellina lectin displays a strong mitogenic effect on …
Thermal aggregation of bovine serum albumin at different pH: comparison with human serum albumin.
2007
We report here a study on thermal aggregation of BSA at two different pH values selected to be close to the isoelectric point (pI) of this protein. Our aim is to better understand the several steps and mechanisms accompanying the aggregation process. For this purpose we have performed kinetics of integrated intensity emission of intrinsic and extrinsic dyes, tryptophans and ANS respectively, kinetics of Rayleigh scattering and of turbidity. The results confirm the important role played by conformational changes in the tertiary structure, especially in the exposure of internal hydrophobic regions that promote intermolecular interactions. We also confirm that the absence of electrostatic repu…
Caseicin 80: purification and characterization of a new bacteriocin from Lactobacillus casei
1990
When grown in complex or synthetic media, Lactobacillus casei B 80 synthesizes a mitomycin C-inducible polypeptide with very specific bactericidal activity against the sensitive strain Lactobacillus casei B 109. The amount of secreted bacteriocin in the culture solution was low, about 1 mg/l. The bacteriocin which we called caseicin 80, was also detectable in cell extracts, although only 2% of the total activity was retained intracellularly. Caseicin 80 was concentrated by ultrafiltration and purified by cation exchange chromatography with Cellulose SE-23 and Superose. The molecular weight was in the range of M r=40,000–42,000 and the isoelectric point was pH 4.5.
Polymeric monolithic microcartridges with gold nanoparticles for the analysis of protein biomarkers by on-line solid-phase extraction capillary elect…
2020
In this study, polymeric monoliths with gold nanoparticles (AuNP@monolith) were investigated as microcartridges for the analysis of protein biomarkers by on-line solid-phase extraction capillary electrophoresis-mass spectrometry (SPE-CE-MS). “Plug-and-play” microcartridges (7 mm) were prepared from a glycidyl methacrylate (GMA)-based monolithic capillary column (5 cm x 250 µm i.d.), which was modified with ammonia and subsequently functionalized with gold nanoparticles (AuNPs). The performance of these novel microcartridges was evaluated with human transthyretin (TTR), which is a protein related to different types of familial amyloidotic polyneuropathies (FAP). Protein retention depended on…
Identification and characterization of a constitutive HSP75 in sea urchin embryos.
1997
Abstract An antiserum against a hsp of the 70-kDa family was prepared, by means of a fusion protein, which was able to detect a constitutive 75-kDa hsc in the sea urchinP. lividus.This hsc was present both during oogenesis and at all developmental stages. A two-dimensional electrophoresis has revealed four isolectric forms of this 75-kDa hsc. The amino acid sequence of the fragment used to prepare the anti-hsp70 antibodies revealed a 43% identity with the corresponding part of sea urchin sperm receptor, and in mature eggs a brighter immunofluorescence was seen all around the cell cortex where the receptor for sea urchin sperm is localized. In oocytes the hsp75 was localized in the cytoplasm…