Human serum albumin chromatography by Cibacron Blue F3GA-derived microporous polyamide hollow-fiber affinity membranes

Affinity Membranes and Monoliths for Protein Purification

Affinity capture represents an important step in downstream processing of proteins and it is conventionally performed through a chromatographic process. The performance of this step highly depends on the type of matrix employed. In particular, resin beads and convective materials, such as membranes and monoliths, are the commonly available supports. The present work deals with non-competitive binding of bovine serum albumin (BSA) on different chromatographic media functionalized with Cibacron Blue F3GA (CB). The aim is to set up the development of the purification process starting from the lab-scale characterization of a commercially available CB resin, regenerated cellulose membranes and polymeric monoliths, functionalized with CB to identify the best option. The performance of the three different chromatographic media is evaluated in terms of BSA binding capacity and productivity. The experimental investigation shows promising results for regenerated cellulose membranes and monoliths, whose performance are comparable with those of the packed column tested. It was demonstrated that the capacity of convective stationary phases does not depend on flow rate, in the range investigated, and that the productivity that can be achieved with membranes is 10 to 20 times higher depending on the initial BSA concentration value, and with monoliths it is approximately twice that of beads, at the same superficial velocity.

Feasibility of a plasma bioassay to assess oxidative protection of low-density lipoproteins by high-density lipoproteins

BACKGROUND

Traditionally, the impact of lipoproteins on vascular disease has been evaluated in light of their quantity, that is, cholesterol content, in plasma. However, recent studies of high-density lipoproteins (HDLs) have focused on functionality with regard to atheroprotection. For example, bioassays have emerged to assess the ability of HDL, in its near native plasma environment, to promote cholesterol removal (efflux) from cells. As a result, attention has focused on developing plasma-based assays for other putative HDL protective functions including protecting low-density lipoproteins (LDLs) from oxidative damage.

OBJECTIVE

To determine the feasibility of such an assay in a complex sample such as plasma, we evaluated the contribution of HDL vs other plasma factors in preventing LDL oxidation.

METHODS

We separated normolipidemic human plasma by gel filtration chromatography and assessed each fraction for its ability to prevent LDL modification by water soluble radical and copper-initiated oxidation mechanisms.

RESULTS

Using proteomics and selective precipitation methods, we identified major antioxidative contributions for fibrinogen, immunoglobulin G, albumin, and small soluble molecules like uric acid and ascorbate, with albumin being especially dominant in copper-initiated mechanisms. HDL particles were minor contributors (∼1%-2%) to the antioxidant capacity of plasma, irrespective of oxidation mechanism.

CONCLUSIONS

Given the overwhelming background of antioxidant capacity inherent to highly abundant plasma proteins, specific bioassays of HDL antioxidative function will likely require its complete separation from plasma.

Semi-Automated Sample Preparation for Plasma Proteomics

The discovery of new biomarkers will be an essential step to enhance our ability to better diagnose and treat human disease. The proteomics research community has recently increased its use of human blood (plasma/serum) as a sample source for these discoveries. However, while blood is fairly non-invasive and readily available as a specimen, it is not easily analyzed by liquid chromatography (LC)/mass spectrometry (MS), because of its complexity. Therefore, sample preparation is a crucial step prior to the analysis of blood. This sample preparation must also be standardized in order to gain the most information from these valuable samples and to ensure reproducibility. We have designed a semi-automated and highly parallel procedure for the preparation of human plasma samples. Our process takes the samples through eight successive steps before analysis by LC/MS: (1) receipt, (2) reformatting, (3) filtration, (4) depletion, (5) concentration determination and normalization, (6) digestion, (7) extraction, and (8) randomization, triplication, and lyophilization. These steps utilize a number of different liquid handlers and liquid chromatography (LC) systems. This process enhances our ability to discover new biomarkers from human plasma.

Anthraquinones As Pharmacological Tools and Drugs

Anthraquinones (9,10-dioxoanthracenes) constitute an important class of natural and synthetic compounds with a wide range of applications. Besides their utilization as colorants, anthraquinone derivatives have been used since centuries for medical applications, for example, as laxatives and antimicrobial and antiinflammatory agents. Current therapeutic indications include constipation, arthritis, multiple sclerosis, and cancer. Moreover, biologically active anthraquinones derived from Reactive Blue 2 have been utilized as valuable tool compounds for biochemical and pharmacological studies. They may serve as lead structures for the development of future drugs. However, the presence of the quinone moiety in the structure of anthraquinones raises safety concerns, and anthraquinone laxatives have therefore been under critical reassessment. This review article provides an overview of the chemistry, biology, and toxicology of anthraquinones focusing on their application as drugs.

Affinity-recognition-based polymeric cryogels for protein depletion studies

Supermacroporous cryogels can be used for the depletion of highly abundant proteins prior to proteome investigations.

The use of NanoTrap particles as a sample enrichment method to enhance the detection of Rift Valley Fever Virus

BACKGROUND

Rift Valley Fever Virus (RVFV) is a zoonotic virus that is not only an emerging pathogen but is also considered a biodefense pathogen due to the threat it may cause to public health and national security. The current state of diagnosis has led to misdiagnosis early on in infection. Here we describe the use of a novel sample preparation technology, NanoTrap particles, to enhance the detection of RVFV. Previous studies demonstrated that NanoTrap particles lead to both 100 percent capture of protein analytes as well as an improvement of more than 100-fold in sensitivity compared to existing methods. Here we extend these findings by demonstrating the capture and enrichment of viruses.

RESULTS

Screening of NanoTrap particles indicated that one particle, NT53, was the most efficient at RVFV capture as demonstrated by both qRT-PCR and plaque assays. Importantly, NT53 capture of RVFV resulted in greater than 100-fold enrichment from low viral titers when other diagnostics assays may produce false negatives. NT53 was also capable of capturing and enhancing RVFV detection from serum samples. RVFV that was inactivated through either detergent or heat treatment was still found bound to NT53, indicating the ability to use NanoTrap particles for viral capture prior to transport to a BSL-2 environment. Furthermore, both NP-40-lysed virus and purified RVFV RNA were bound by NT53. Importantly, NT53 protected viral RNA from RNase A degradation, which was not observed with other commercially available beads. Incubation of RVFV samples with NT53 also resulted in increased viral stability as demonstrated through preservation of infectivity at elevated temperatures. Finally, NanoTrap particles were capable of capturing VEEV and HIV, demonstrating the broad applicability of NanoTrap particles for viral diagnostics.

CONCLUSION

This study demonstrates NanoTrap particles are capable of capturing, enriching, and protecting RVFV virions. Furthermore, the use of NanoTrap particles can be extended to a variety of viruses, including VEEV and HIV.

Analysis of Cibacron blue F3G-A interaction with therapeutic proteins by MALDI-TOF mass spectrometry

The formation of the complexes between Cibacron blue F3G-A and two therapeutic proteins, recombinant human interferon-alpha2b and recombinant human growth hormone, was investigated. The method of time-resolved limited proteolysis coupled with MALDI-TOF mass spectrometry was used. The analysis of peptide maps revealed that A(17)HR(19) and L(20)HQLAFDTYQEFEEAYIPK(38) of hGH, and R(14)TLMLLAQMR(23) and D(33)RHDFGFPQEEFGNQFQK(50) of hIFN-alpha2b, exhibit affinity to Cibacron blue F3G-A.

Adsorption of papain with Cibacron Blue F3GA carrying chitosan-coated nylon affinity membranes

Covalent coupling of chitosan (CS) to activated nylon membrane was performed after the reaction of the microporous nylon membrane with formaldehyde. Non-specific adsorption on the CS-coated nylon membrane decreased greatly, compared with plain nylon membrane. The dye Cibacron Blue F3GA (CB F3GA) as a ligand was then covalently immobilized on the CS-coated membranes. Physical properties of the composite membrane and its applications in affinity membrane chromatography were examined. The contents of CS and CB F3GA-attached membranes were 89.6 mg/g nylon membrane and 146.1 micromol/g nylon membrane, respectively. These CB F3GA-attached composite membranes were used in the papain adsorption studies. Higher papain adsorption capacity, up to 235.3mg/g affinity membrane, was obtained. The adsorption isotherm fitted the Freundlich model well. Significant amount of the adsorbed papain (about 94.3%) was eluted by 1.0M NaSCN at pH 9.0. Experiments on regeneration and dynamic adsorption were also performed. It appears that CB F3GA-CS nylon membranes can be applied for papain separation without causing any denaturation.

N-methacryloly-(L)-histidinemethylester carrying a pseudospecific affinity sorbent for immunoglobulin-G isolation from human plasma in a column system

N-methacryloly-(L)-histidinemethylester (MAH) as a pseudospecific ligand was synthesized by using methacryloyl chloride and histidine. Spherical beads with an average size of 63-75 microm were obtained by suspension polymerization of ethylene glycol dimethacrylate (EGDMA), 2-hydroxyethyl methacrylate (HEMA) and MAH conducted in an aqueous dispersion medium. The specific surface area of the beads was found to be 18.3 m2/g. Poly(EGDMA-HEMA-MAH) beads were used in the separation of immunoglobulin-G (HIgG) from aqueous solutions and/or human plasma in a packed-bed column system. HIgG adsorption capacity of the beads decreased with an increase in the flow-rate of plasma. The maximum HIgG adsorption on the poly(EGDMA-HEMA-MAH) sorbents was observed at pH 7.4. HIgG adsorption onto the poly(EGDMA-HEMA) sorbents was negligible. Higher adsorption values (up to 135 mg/g) were obtained when the poly(EGDMA-HEMA-MAH) sorbents were used from aqueous solutions. HIgG adsorption increased with decreasing temperature and the maximum adsorption achieved at 4 degrees C. MAH incorporation significantly affected HIgG adsorption capacity (135 mg/g). Higher amounts of HIgG were adsorbed from human plasma (up to 165 mg/g). Adsorption capacities of other blood proteins were obtained as 8.7 mg/g for fibrinogen and 14.6 mg/g for albumin. The total protein adsorption was determined as 191 mg/g. The pseudospecific affinity beads allowed one-step separation of HIgG from human plasma. HIgG molecules could be repeatedly adsorbed and desorbed with these sorbents without noticeable loss in their HIgG adsorption capacity.

Dye-ligand affinity systems

Dye-ligands have been considered as one of the important alternatives to natural counterparts for specific affinity chromatography. Dye-ligands are able to bind most types of proteins, in some cases in a remarkably specific manner. They are commercially available, inexpensive, and can easily be immobilized, especially on matrices bearing hydroxyl groups. Although dyes are all synthetic in nature, they are still classified as affinity ligands because they interact with the active sites of many proteins mimicking the structure of the substrates, cofactors, or binding agents for those proteins. A number of textile dyes, known as reactive dyes, have been used for protein purification. Most of these reactive dyes consist of a chromophore (either azo dyes, anthraquinone, or phathalocyanine), linked to a reactive group (often a mono- or dichlorotriazine ring). The interaction between the dye ligand and proteins can be by complex combination of electrostatic, hydrophobic, hydrogen bonding. Selection of the supporting matrix is the first important consideration in dye-affinity systems. There are several methods for immobilization of dye molecules onto the support matrix, in which usually several intermediate steps are followed. Both the adsorption and elution steps should carefully be optimized/designed for a successful separation. Dye-affinity systems in the form of spherical sorbents or as affinity membranes have been used in protein separation.