Wash Buffer II for ChIP (High-Salt)

Evaluating the efficacy of immobilized metal affinity chromatography (IMAC) for host cell protein (HCP) removal from anti-HER2 scFv expressed in Escherichia coli

DNA isolation is one of the most crucial part in DNA analysis and is reflected by the abundance of ready-to-use DNA isolation kits available in the market. However, the chaotropic salts used in conventional kits during the binding step has been known to inhibit the downstream process of PCR and deteriorate when exposed to air. This study aims to design a better and faster DNA isolation process with better DNA isolation performance to replace the conventional one. This study aims to replace the chaotropic salt in binding buffer with organic acids or salt and improve the buffer used during the wash step. Sodium perchlorate and several other salts and acids were chosen as candidates for the binding buffer. Simultaneously, 10Mm NaCl and 10Mm Tris-Cl with varying concentrations of organic solvents were selected as candidates for the wash buffer. The performance of the selected buffers was then compared to the readily available commercial kit. Organic acid B was among the best candidates for binding buffer with 81.91% and 83.20% recovery rates. For wash buffer, it was observed that the DNA recovery increases with an increasing organic solvent concentration in 10Mm NaCl and 10Mm Tris-Cl. Wash buffer with 90% organic solvent shows the best compromise of DNA yield and purity compared to 70%, 80%, and 100% organic solvent concentration in 10Mm NaCl and 10Mm Tris-Cl. A combination of organic acid B in binding buffer and 90% organic solvent A in wash buffer were tested against a commercial DNA extraction kit. The combination of organic acid B and 90% organic solvent yielded 72.81 ng/ul compared to 28.46 ng/ul by the commercial kit. The combination of the binding buffer organic acid B and 90% organic solvent in 10Mm NaCl and 10Mm Tris-Cl can replace the current commercial kits without the problems posed by the presence of chaotropic salt.

Inhalational anthrax is caused by spores of the bacterium Bacillus anthracis (B. anthracis), and is an extremely dangerous disease that can kill unvaccinated victims within 2 weeks. Modern antibiotic-based therapy can increase the survival rate to ∼50%, but only if administered presymptomatically (within 24-48 h of exposure). To discover host signaling responses to presymptomatic anthrax, label-free quantitative phosphoproteomics via liquid chromatography coupled to mass spectrometry was used to compare spleens from uninfected and spore-challenged mice over a 72 h time-course. Spleen proteins were denatured using urea, reduced using dithiothreitol, alkylated using iodoacetamide, and digested into peptides using trypsin, and the resulting phosphopeptides were enriched using titanium dioxide solid-phase extraction and analyzed by nano-liquid chromatography-Linear Trap Quadrupole-Orbitrap-MS(/MS). The fragment ion spectra were processed using DeconMSn and searched using both Mascot and SEQUEST resulting in 252,626 confident identifications of 6248 phosphopeptides (corresponding to 5782 phosphorylation sites). The precursor ion spectra were deisotoped using Decon2LS and aligned using MultiAlign resulting in the confident quantitation of 3265 of the identified phosphopeptides. ANOVAs were used to produce a q-value ranked list of host signaling responses. Late-stage (48-72 h postchallenge) Sterne strain (lethal) infections resulted in global alterations to the spleen phosphoproteome. In contrast, ΔSterne strain (asymptomatic; missing the anthrax toxin) infections resulted in 188 (5.8%) significantly altered (q<0.05) phosphopeptides. Twenty-six highly tentative phosphorylation responses to early-stage (24 h postchallenge) anthrax were discovered (q<0.5), and ten of these originated from eight proteins that have known roles in the host immune response. These tentative early-anthrax host response signaling events within mouse spleens may translate into presymptomatic diagnostic biomarkers of human anthrax detectable within circulating immune cells, and could aid in the identification of pathogenic mechanisms and therapeutic targets.

Normal platelets were examined by conventional coagulation methods and specific immunological techniques for the presence of platelet-associated coagulation factors. Platelets washed in buffer containing calcium chloride gave different results form those washed in the absence of calcium. Factor XI was not detected in washed platelets by any technique. Factor II and factor X were removed from platelets by washing in calcium-free buffer but not by calcium-containing buffer. Procoagulant factor VIII was readily removed or inactivated by washing in the presence or absence of calcium, but factor VIII related antigen was consistently demonstrated after multiple washes in either buffer. Factor V activity and antigen was detected in platelet suspensions after multiple washes although the presence of calcium in the washing buffer gave higher factor V assays and stronger immunological reactions than when calcium-free buffer was used. The results are consistent with the presence of calcium dependent binding sites in platelets which may have a role in the enhancement of factor V and phospholipid reactions.

Zeta potential, defined as the electric charge at the shear plane, is widely used as a proxy parameter for bacterial cell surface charge. Nonspecific adsorption of ions or polyelectrolytes onto the cell surface, however, alters the value and polarity of the measured zeta potential, leading to erroneous results. Multiple wash and centrifugation steps are commonly used in preparing cells for zeta potential analysis, where various wash buffers (such as 9 g/L NaCl, 0.001M KCl, and 0.1M NaNO3) are routinely used for removing (by charge screening) ions and charged molecules that bind nonspecifically to the cell surface. Using Escherichia coli DH5α grown in LB Lennox (with 2 g/L glucose), experiment data showed that the zeta potential-pH profile was not significantly different over the pH range from 2 to 12 for deionized water, 9 g/L NaCl, and phosphate buffer saline (PBS) wash buffers. As LB Lennox is a low salt medium without a phosphate buffer, it was likely that the extent of nonspecific adsorption of ions on the cell surface was not severe, and the different wash buffers would correspondingly not exert much effect on measured zeta potential. Zeta potential-pH profiles for E. coli grown in a semi-defined medium (with a high capacity phosphate buffer system), on the other hand, was significantly different over the pH range from 1 to 12 for deionized water, 9 g/L NaCl, 0.1M NaNO3, 0.1M sodium acetate, and 0.1M sodium citrate wash buffers with the deviation positively correlated with wash buffer’s ionic strength. Furthermore, the point of zero charge (pHzpc) for E. coli grown in the semi-defined medium varies between 1.5 and 3, in an ionic strength dependent manner, for the various wash buffers tested. Collectively, this preliminary study highlights the importance of wash buffer ionic strength in affecting removal efficiency of non-specifically absorbed ions on bacterial cell surface, where a threshold exists (0.15M) for charge screening to be effective. At the upper bound, 0.6M ionic strength might remove cations intrinsic to the cell envelope, leading to possible cell surface damage and erroneous measurements.

Pharmacologic approaches to studying palmitoylation are limited by the lack of specific inhibitors. Recently, screens have revealed five chemical classes of small molecules that inhibit cellular processes associated with palmitoylation (Ducker, C. E., L. K. Griffel, R. A. Smith, S. N. Keller, Y. Zhuang, Z. Xia, J. D. Diller, and C. D. Smith. 2006. Discovery and characterization of inhibitors of human palmitoyl acyltransferases. Mol. Cancer Ther. 5: 1647-1659). Compounds that selectively inhibited palmitoylation of N-myristoylated vs. farnesylated peptides were identified in assays of palmitoyltransferase activity using cell membranes. Palmitoylation is catalyzed by a family of enzymes that share a conserved DHHC (Asp-His-His-Cys) cysteine-rich domain. In this study, we evaluated the ability of these inhibitors to reduce DHHC-mediated palmitoylation using purified enzymes and protein substrates. Human DHHC2 and yeast Pfa3 were assayed with their respective N-myristoylated substrates, Lck and Vac8. Human DHHC9/GCP16 and yeast Erf2/Erf4 were tested using farnesylated Ras proteins. Surprisingly, all four enzymes showed a similar profile of inhibition. Only one of the novel compounds, 2-(2-hydroxy-5-nitro-benzylidene)-benzo[b]thiophen-3-one [Compound V (CV)], and 2-bromopalmitate (2BP) inhibited the palmitoyltransferase activity of all DHHC proteins tested. Hence, the reported potency and selectivity of these compounds were not recapitulated with purified enzymes and their cognate lipidated substrates. Further characterization revealed both compounds blocked DHHC enzyme autoacylation and displayed slow, time-dependent inhibition but differed with respect to reversibility. Inhibition of palmitoyltransferase activity by CV was reversible, whereas 2BP inhibition was irreversible.

Understanding virus retention mechanisms on protein a chromatography based on using different wash buffers – Evaluating the possibility for a generic wash buffer toolbox to improve virus clearance capacity

This study represents the first scanning electron microscope (SEM) evaluation of cestode larvae infecting Red Sea fish. General structures of the larvae and different types of microtriches on the integument are described.Plerocercoids of Trypanorhyncha were collected from the mesenteries and liver of Cephalopholis oligostricta. The capsule of each larva was opened, the plerocercoid was removed and fixed in 10% formalin. Following buffer (pH. 7.3) wash, they were fixed in OSO4 12 hr, washed in buffer, immersed in 2% tannic acid 8 hr, washed in buffer, fixed again in OSO4 2 hr, buffer washed, dehydrated, critical point dried, and sputter coated with gold.The plerocercoids were identified as belonging to the genus Otobothrium. Each organism was divided into a scolex and body. The scolex consisted of two large bothria, each bothrium was nearly round in outline and possessed two circular invaginations on its posterior margin. On the apex of the scolex, four extended tentacles covered with hooks were observed (Fig 1).

We report characterization of a novel testis- and sperm-specific protein, FSCB (fibrous sheath CABYR binding), that is expressed post-meiotically and localized in mouse sperm flagella. FSCB was identified as a binding partner of CABYR, a calcium-binding protein that is tyrosine-phosphorylated during capacitation. Orthologous genes of FSCB are present in other mammals, including rat and human, and conserved motifs in FSCB include PXXP, proline-rich and extensin-like regions. FSCB is phosphorylated by protein kinase A as shown by in vitro phosphorylation assay and also by determining phosphorylation sites in native FSCB from mouse sperm. Calcium overlay assay showed that FSCB is a calcium-binding protein from sperm. FSCB is a post meiotic protein first expressed at step 11 of mouse spermatogenesis in the elongating spermatids, and it subsequently incorporates into the flagellar principal piece of the sperm. Ultrastructurally, FSCB localized to a cortical layer of intermediate electron density at the surface of the ribs and longitudinal columns of the fibrous sheath. Due to its temporal appearance during spermiogenesis and location at the cortex of the fibrous sheath, FSCB is postulated to be involved in the later stages of fibrous sheath assembly.

The sperm acrosome is a large secretory granule that undergoes calcium-stimulated exocytosis by a mechanism analogous to neuronal secretion. In neurons the core SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex, composed of syntaxin (Stx), SNAP-25, and VAMP2, mediates vesicle fusion, whereas calcium regulation is thought to be accomplished by the synaptotagmin (Syt) family, some of which exhibit calcium-dependent binding to syntaxin and SNAP-25. Sperm express Syt VI and VIII and Stx2, which are co-localized to the acrosomal compartment where they might mediate exocytosis in response to calcium influx. Therefore, we examined the calcium dependence and isoform-specific interaction of Syt and Stx. We found that Stx2 binds to Syt I, VI, and VIII in a calcium-dependent manner with EC(50) values of 175, 233, and 96 mum calcium, respectively. We also determined that the EC(50) for calcium of the acrosome reaction in streptolysin O-permeabilized sperm is 87 mum, which closely coincides with the calcium sensitivity of Stx2 and Syt VIII interaction. Consistent with this is the greater potency of recombinant Syt VIII, VI, and Stx2 compared with other isoforms in inhibiting the acrosome reaction in streptolysin O-permeabilized sperm. Similarly, introduction of Syt VIII-specific antibodies was equally effective in inhibiting the acrosome fusion. Taken together, our data suggest a critical role for Syt VIII and Stx2 in membrane fusion and acrosome reaction in the sperm.

Streptococcus pyogenes AP1, a strain of the highly virulent M1 serotype, uses exclusively protein H to bind the complement inhibitor C4b-binding protein (C4BP). We found a strong correlation between the ability of AP1 and its isogenic mutants lacking protein H to inhibit opsonization with complement C3b and binding of C4BP. C4BP bound to immobilized protein H or AP1 bacteria retained its cofactor activity for degradation of (125)I-C4b. Furthermore, C4b deposited from serum onto AP1 bacterial surfaces was processed into C4c/C4d fragments, which did not occur on strains unable to bind C4BP. Recombinant C4BP mutants, which (i) lack certain CCP domains or (ii) have mutations in single aa as well as (iii) mutants with additional aa between different CCP domains were used to determine that the binding is mainly mediated by a patch of positively charged amino acid residues at the interface of domains CCP1 and CCP2. Using recombinant protein H fragments, we narrowed down the binding site to the N-terminal domain A. With a peptide microarray, we identified one single 18-amino acid-long peptide comprising residues 92-109, which specifically bound C4BP. Biacore was used to determine KD = 6 × 10(-7) M between protein H and a single subunit of C4BP. C4BP binding also correlated with elevated levels of adhesion and invasion to endothelial cells. Taken together, we identified the molecular basis of C4BP-protein H interaction and found that it is not only important for decreased opsonization but also for invasion of endothelial cells by S. pyogenes.

<i>Citrus tristeza closterovirus</i>

Bacterial cell surface carries an electrical charge due to the myriad functional groups present, as well as assortment of ions and molecules non-specifically adsorbed to the cell surface. Thus, solution in contact with the bacterial cell surface play a critical role in influencing the overall surface charge characteristics through conferring non-specifically adsorbed ions and molecules. Various wash buffers are commonly used in removing non-specifically adsorbed ions and molecules for revealing the real surface charge of the bacterium. Using electrophoretic mobility measurement of zeta potential, this study attempted to understand the surface charge characteristics of Bacillus subtilis NRS-762 (ATCC 8473) with the help of three wash buffers: deionized (DI) water, 0.1M sodium nitrate, and 9 g/L sodium chloride. Experiment results revealed that B. subtilis NRS-762 was negatively charged over the entire pH range from 1.5 to 12. Specifically, with deionized water as wash buffer, the point-of-zero-charge (pHzpc) was at pH 1.5, which indicated that large amount of negatively charged functional groups were present on the cell surface. Comparison between the zeta potential-pH profiles of B. subtilis NRS-762 cultivated at 30 oC and 37 oC revealed that the profile for growth at 37 oC was more negatively charged over the entire pH range compared to that for growth at 30 oC. This highlighted that physiological adaptation might had occurred on the cell surface for coping with growth at a higher temperature. Zeta potential-pH profiles obtained revealed that DI water could not remove significant quantities of the non-specifically adsorbed ions and molecules. On the other hand, the zeta potential-pH profiles of cells washed with 0.1M sodium nitrate and 9 g/L sodium chloride overlapped each other substantially and were more negatively charged over the pH range from 2 to 11, compared to that of cells washed with DI water. This revealed substantial removal of non-specifically adsorbed ions and molecules with the use of 0.1M sodium nitrate (0.1M ionic strength) and 9 g/L sodium chloride (0.15M ionic strength), which helped reveal the actual surface charge of B. subtilis NRS-762 cells. Collectively, actual surface charge of B. subtilis NRS-762 was masked by non-specifically adsorbed ions and molecules, which could be removed by 0.1M sodium nitrate and 9 g/L sodium chloride wash buffer. Thus, in the case of B. subtilis NRS-762, 0.1M ionic strength wash buffer was the threshold at which there was complete removal of non-specifically adsorbed ions and molecules from the cell surface.

Identification and characterization of BEND2 as a novel and key regulator of meiosis during mouse spermatogenesis

To evaluate the influence of pretreatment IgG against streptokinase on the outcome of streptokinase treatment in acute myocardial infarction. Coronary care unit. From 88 patients admitted to the coronary care unit due to chest pain, blood samples were taken for determination of the pre-existing titre of antibodies against streptokinase. The patients were treated and monitored according to standard protocols. Fifty of the patients received thrombolytic therapy with streptokinase due to acute myocardial infarction and were monitored with continuous dynamic vectorcardiography, making possible the continuous analysis of ST- and QRS-vector changes and determination of the event of reperfusion. None of these 50 patients had been given streptokinase therapy previously. According to the vectorcardiographic criteria 21(42%) patients had signs of early (within 2 h) reperfusion after streptokinase therapy. These patients had lower pre-existing antibody titres than patients without signs of reperfusion (mean values 0.20 and 0.45 arbitrary units, P = 0.01). None of the patients with a titre higher than 0.50 arbitrary units (nine patients) had signs of early reperfusion. Of the 41 patients with a titre lower than 0.50 arbitrary units 52.5% had signs of early reperfusion. The present investigation indicates that pre-existing streptokinase antibodies play an important role in reperfusion failure during thrombolytic therapy with streptokinase in acute myocardial infarction. Therefore, the determination of streptokinase antibodies may differentiate between those patients who may benefit from streptokinase treatment and those who should be treated with some other regime.