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21.
I. T. L. Bresolin M. Borsoi-Ribeiro W. M. S. C. Tamashiro E. F. P. Augusto M. A. Vijayalakshmi S. M. A. Bueno 《Applied biochemistry and biotechnology》2010,160(7):2148-2165
Monoclonal antibodies (MAbs) have been used for therapies and some analytical procedures as highly purified molecules. Many
techniques have been applied and studied, focusing on monoclonal antibodies purification. In this study, an immobilized metal
affinity chromatography membrane was developed and evaluated for the purification of anti-TNP IgG1 mouse MAbs from cell culture supernatant after precipitation with a 50% saturated ammonium sulfate solution. The chelating
ligands iminodiacetic acid, carboxymethylated aspartic acid (CM-Asp), nitrilotriacetic acid, and tris (carboxymethyl) ethylenediamine
in agarose gels with immobilized Ni(II) and Zn(II) ions were compared for the adsorption and desorption of MAbs. The most
promising chelating ligand—CM-Asp—was then coupled to poly(ethylene vinyl alcohol) (PEVA) hollow fiber membranes. According
to SDS-PAGE and ELISA analyses, a higher selectivity and a purification factor of 85.9 (fraction eluted at 500 mM Tris) were
obtained for IgG1 using PEVA-CM-Asp-Zn(II). The anti-TNP MAb could be eluted under mild pH conditions causing no loss of antigen binding capacity. 相似文献
22.
A Mueller-matrix imaging polarimeter was developed to measure spatially resolved polarization properties in the living human eye. The apparatus is a double-pass setup that incorporates two liquid-crystal variable retarders and a slow-scan CCD camera in the recording stage. Series of 16 images for the combinations of independent polarization states in the first and second passages were recorded for two experimental conditions: with the camera conjugated either with the retina or with the eye's pupil plane. Spatially resolved collections of Mueller matrices and the degree of polarization were calculated from those images for both retinal and pupil planes. 相似文献
23.
Maqueda M Gálvez A Bueno MM Sanchez-Barrena MJ González C Albert A Rico M Valdivia E 《Current protein & peptide science》2004,5(5):399-416
After the discovery of bacteriocin AS-48, a 70-residue cyclic peptide produced by Enterococcus faecalis subsp. liquefaciens, some naturally-occurring cyclic proteins from bacteria have been reported. AS-48 is encoded by the 68-kb pheromone-responsive plasmid pMB2, and the gene cluster involved in production and immunity has been identified and sequenced. This peptide exerts a bactericidal action on sensitive cells (most of the Gram-positive and some Gram-negative bacteria). Its target is the cytoplasmic membrane, in which it opens pores, leading to the dissipation of the proton motive force and cell death, a mechanism similar to that proposed for the action of defensins or, most generally, cationic antibacterial peptides. This fact, together with its remarkable stability and solubility over a wide pH range, suggest that this bacteriocin could be a good candidate as a natural food preservative. The amino acid composition of purified AS-48 shows the absence of modified or dehydrated residues, making it clearly different from lantibiotics. Bacteriocin AS-48 also differs from defensins in that it does not contain cysteines and consequently no disulfide bridges, which makes is high stability even more remarkable. Composition analysis of AS-48 shows a high proportion of basic to acidic amino acids, conferring to this peptide a strong basic character, with an isoelectric point close to 10.5. Determination of the AS-48 structural gene DNA sequence, together with the sequences of AS-48 protease digestion fragments and mass spectrometry determinations, allowed us to determine unambiguously the cyclic structure of the molecule, being the first example of a posttranslational modification in which a cyclic structure arises from a "head-to-tail" linkage. We have solved the three-dimensional structure of AS-48 in solution, and it consists of a globular arrangement of five alpha-helices enclosing a compact hydrophobic core. Interestingly, the head-to-tail peptide link between Trp-70 and Met-1 lies in the middle of alpha-helix 5, which is shown to have a pronounced effect on the stability of the three-dimensional structure. Analysis of structure-function relationship allowed us to propose models to understand the aspects of the molecular function of AS-48. The purpose of this work is to review recent developments in our understanding about the biochemical and biological characteristics and structure of this unusual type of bacteriocin. 相似文献
24.
We have developed an aberro-polariscope that simultaneously measures spatially resolved polarization properties and wave-front aberration in a living human eye. The setup consists of an infrared Hartmann-Shack sensor that incorporates a polariscope. A series of four Hartmann-Shack images corresponding to independent polarization states were recorded. The corresponding wave-front aberration was computed from each image. Moreover, from each set of four images spatially resolved (over the pupil plane) parameters of polarization were also determined. This instrument allows useful information on both the optical and the biomechanical properties of the eye to be obtained. 相似文献
25.
Mariele M. Pedroso Ailton M. Watanabe Maria Cristina Roque-Barreira Paulo R. Bueno Ronaldo C. Faria 《Microchemical Journal》2008,89(2):153-158
A Quartz Crystal Microbalance (QCM) was used to monitor the mass changes on a quartz crystal surface containing immobilized lectins that interacted with carbohydrates. The strategy for lectin immobilization was developed on the basis of a multilayer system composed of Au–cystamine–glutaraldehyde–lectin. Each step of the immobilization procedure was confirmed by FTIR analysis. The system was used to study the interactions of Concanavalin A (ConA) with maltose and Jacalin with Fetuin. The real-time binding of different concentrations of carbohydrate to the immobilized lectin was monitored by means of QCM measurements and the data obtained allowed for the construction of Langmuir isotherm curves. The association constants determined for the specific interactions analyzed here were (6.4 ± 0.2) × 104 M− 1 for Jacalin–Fetuin and (4.5 ± 0.1) × 102 M− 1 for ConA–maltose. These results indicate that the QCM constitutes a suitable method for the analysis of lectin–carbohydrate interactions, even when assaying low molecular mass ligands such as disaccharides. 相似文献
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Using martingale methods in reliability theory we developed the Barlow and Proschan reliability importance of a pattern to the system reliability under dependence conditions. We allowed several levels of information to calculate the importance measure. 相似文献
30.
In this paper, we consider shifted tridiagonal matrices. We prove that the standard algorithm to compute the LU factorization
in this situation is mixed forward-backward stable and, therefore, componentwise forward stable. Moreover, we give a formula
to compute the corresponding condition number in O(n) flops.
This research has been partially supported by Dirección General de Investigación (Ministerio de Ciencia y Tecnología) of Spain
through grants BFM2003-06335-C03-02 and MTM2006-06671 as well as by the Postdoctoral Fellowship EX2004-0658 provided by Ministerio
de Educación y Ciencia of Spain. 相似文献