Publications by authors named "Milos Barut"

The serotype specificity of adenovirus ion-exchange chromatography has previously been studied using standard particle-based columns, and the hexon protein has been reported to determine retention time. In this study, we have submitted Adenovirus type 5 recombinants to anion-exchange chromatography using methacrylate monolithic supports. Our experiments with hexon-modified adenoviral vectors show more precisely that the retention time is affected by the substitution of amino acids in hypervariable region 5, which lies within the hexon DE1 loop.

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In order to perform their function, proteins frequently interact with other proteins. Various methods are used to reveal protein interacting partners, and affinity chromatography is one of them. Snake venom is composed mostly of proteins, and various protein complexes in the venom have been found to exhibit higher toxicity levels than respective components separately.

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HPLC based analytical assay is a powerful technique that can be used to efficiently monitor plasmid DNA (pDNA) purity and quantity throughout the entire purification process. Anion exchange monolithic and non-porous particle based stationary phases were used to study the recovery of the different pDNA isoforms from the analytical column. Three differently sized pDNA molecules of 3.

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To exploit different chromatographic modes for efficient plasmid DNA (pDNA) purification a novel monolithic chromatographic support bearing multimodal histamine (HISA) groups was developed and characterized. Electrostatic charge of HISA groups depends on the pH of the mobile phase, being neutral above pH 7 and becoming positively charged below. As a consequence, HISA groups exhibit predominantly ion-exchange character at low pH values, which decreases with titration of the HISA groups resulting in increased hydrophobicity.

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Potato spindle tuber viroid (PSTVd) is the causal agent of a number of agriculturally important diseases. It is a single-stranded, circular and unencapsidated RNA molecule with only 356-360 nucleotides and no coding capacity. Because of its peculiar structural features, it is very stable ex vivo and it is easily transmitted mechanically by contaminated hands, tools, machinery, etc.

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The production of economically acceptable viral vaccines of high quality requires simple and efficient methods for purification and concentration of viral particles. Ion-exchange chromatography (IEC) has become one of commonly used methods for large-scale downstream purification of viruses. Viruses possess different biological and/or biochemical properties and therefore IEC conditions must be established specifically for each virus.

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Adenovirus type 3 dodecahedric virus-like particles (Ad3 VLP) are an interesting delivery vector. They penetrate animal cells in culture very efficiently and up to 300,000 Ad3 VLP can be observed in one cell. The purification of such particles usually consists of several steps.

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Monoliths are chromatographic stationary phases, which were specially designed for efficient purification of large biomolecules, like proteins, viruses and DNA. In this work, the small scale monolithic butyl (C4) and styrene-divinyl benzene (SDVB) columns were applied for reversed phase analyses of various degraded influenza viruses. The binding of the HA1 subunit of haemagglutinin to the monolithic columns was confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and the Western blot.

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Monoliths represents the 4th generation of chromatographic supports. They consist of a single piece of highly porous material with interconnected flow through pores. Because of that transport is based on convection what results in a flow unaffected separation and dynamic binding capacity.

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To support effective process development there is a requirement for rapid analytical methods that can identify and quantitate adenoviral particles throughout the manufacturing process, from cellular lysate through to purified adenovirus. An anion-exchange high-performance liquid chromatography method for the analysis of adenovirus type 5 (Ad5) particles has been developed using a novel quaternary amine monolithic column (Bio-Monolith QA, Agilent). The developed method separates intact Ad5 from contaminating proteins and DNA, thus allowing analysis of non-purified samples during process development.

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Human serum albumin (HSA) and immunoglobulin G (IgG) represent over 75% of all proteins present in human plasma. These high-abundance proteins prevent the detection of low-abundance proteins which are potential markers for various diseases. The depletion of HSA and IgG is therefore essential for further proteome analysis.

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This review describes the novel chromatography stationary phase--a porous monolithic methacrylate-based polymer--in terms of the design of the columns and some of the features that make these columns attractive for the purification of large biomolecules. We first start with a brief summary of the characteristics of these large molecules (more precisely large proteins like immunoglobulins G and M, plasmid deoxyribonucleic acid (DNA), and viral particles), and a list of some of the problems that were encountered during the development of efficient purification processes. We then briefly describe the structure of the methacrylate-based monolith and emphasize the features which make them more than suitable for dealing with large entities.

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A high-performance liquid chromatography (HPLC) method for the determination of DNA entrapment efficiency in liposomes has been developed. Plasmid DNA was encapsulated into positively charged liposomes. Non-entrapped DNA was separated by ultracentrifugation from liposomes and supernatant was chromatographed on Convective Interaction Media (CIM) DEAE disk.

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In order to enable the detection of low abundance proteins from human plasma, it is necessary to remove high abundance proteins. Among them, human serum albumin and immunoglobulin G represent more than 75% of all such proteins. In this paper, the characterization of short monolithic columns was performed followed by the optimization of a multidimensional approach, known as conjoint liquid chromatography, to deplete human serum albumin and immunoglobulin G from a human plasma sample.

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New therapeutics that are being developed rely more and more on large and complex biomacromolecules like proteins, DNA, and viral particles. Manufacturing processes are being redesigned and optimized both upstream and downstream to cope with the ever-increasing demand for the above target molecules. In downstream processing, LC still represents the most powerful technique for achieving high yield and high purities of these molecules.

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The isolation and purification of nucleic acids is essential for many procedures in molecular biology. After showing that bacterial and eukaryotic genomic DNA can be specifically bound to the CIM DEAE monolithic column, this characteristic was exploited in development of a simple and fast chromatographic procedure for isolation and purification of genomic DNA from cell lysates that does not include the usage of toxic organic solutions. The purity and the quality of the isolate as well as the duration of the procedure was similar to other chromatographic methods used today for isolation of genomic DNA, but the initial sample volume was not restricted.

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Analysis of crude samples from biotechnological processes is often required to demonstrate that residual host cell impurities are reduced or eliminated during purification. Current knowledge suggests that a continuous-cell-line DNA can be considered a cellular contaminant rather than a significant risk factor requiring removal to extremely low levels. Anion-exchange chromatography is one of the most important methods used in the downstream processing and analysis of different biomolecules.

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Anion-exchange chromatography is one of the most important methods in downstream processing of plasmid DNA, both as a process and as an analytical technique. Separation of plasmid DNA on traditional particle-based anion-exchange supports is usually slow. Moreover, such supports have a low capacity for plasmid DNA due to the steric exclusion effects.

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Monolithic chromatography media represent a novel generation of stationary phases introduced in the last 10-15 years providing a chromatography matrix with enhanced mass transfer and hydrodynamic properties. These features allow for an efficient and fast separation of especially large biomolecules like e.g.

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Monolithic supports represent a novel type of stationary phases for liquid and gas chromatography, for capillary electrochromatography, and as supports for bioconversion and solid phase synthesis. As opposed to individual particles packed into chromatographic columns, monolithic supports are cast as continuous homogeneous phases. They represent an approach that provides high rates of mass transfer at lower pressure drops as well as high efficiencies even at elevated flow rates.

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