Notes: The authors showed that LipL32, a major surface-exposed protein of Leptospira sp., bound to the host extracellular matrix (ECM). They expressed and purified recombinant LipL32 for use in a solid-phase binding assay to test its ability to bind to ECM proteins. LipL32 was expressed with an N-terminal biotin-acceptor tag and purified using the SoftLink™ Soft Release Avidin Resin. (3899)

Notes: To investigate the importance of the zinc knuckle motif of early B cell factor (EBF) in DNA binding and transcription activation of target genes, the authors used a baculovirus system to express wildtype and mutated forms of EBF, then purified the proteins for use in DNA-binding assays. The EBF proteins were expressed with a biotinylated tag and purified using SoftLink™ Soft Release Avidin Resin. (3917)

Notes: To determine which proteins are present in DNA replication complexes, the authors used biotin-tagged replication proteins as nanoscale biopointers. T4 DNA replication complexes were recreated in vitro, and biotin-tagged replication proteins were substituted for wildtype replication proteins. Streptavidin was allowed to bind to the biotin-tagged proteins, and the replication complexes were visualized by electron microscopy. The biotin-tagged helicase and DNA polymerase were purified from E. coli using SoftLink™ Soft Release Avidin Resin. (3806)

Notes: The authors developed a new method for analyzing interactions between lipids and lipid transfer proteins, using sterol carrier protein-2 (SCP-2) as a prototype. SCP-2 was expressed with a modified AviTag, consisting of a prolyl-rich semi-rigid hinge linker and the biotinylated AviTag, in E. coli. Biotinylated SCP-2 was purified using the SoftLink™ Soft Release Avidin Resin and an elution buffer containing 5mM biotin. Matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry was used to confirm and SCP-2 contained a single biotin moiety at the expected position. Biotinylated SCP-2 was then immobilized on a streptavidin-coated chip, and the on- and off-rate constants of various lipids were determined using surface plasmon resonance. When expressing biotinylated SCP-2, the authors cotransfected E. coli with the SCP-2 expression construct and a plasmid encoding biotin ligase to enhance biotin ligation. (3855)

Notes: The authors examined the interaction between poly(ADP-ribose) (PAR) and PAR-binding proteins as a function of PAR chain length. ADP-ribose chains of various lengths were end-labeled with a biotin moiety, then size fractionated by high-resolution anion exchange HPLC. Purification of ADP-ribose chains of defined lengths was performed with the SoftLink™ Soft Release Avidin, and the ADP-ribose chains were used in a novel electrophoretic mobility shift assay. (3802)

Notes: The authors show that substitution of alanine for the conserved glycine 224 of Nog1, a eukaryotic GTPase, disrupts assembly of pre-60S ribosome subunits but does not significantly affect GTP binding. Amino acids 1–357 of Nog1 (Nog1NG) were expressed with an N-terminal biotinylated tag in E. coli, then purified using the SoftLink™ Soft Release Avidin Resin. The resin was incubated with the cleared lysate for 2 hours with mixing and washed with B300 buffer (25mM Tris-HCl [pH7.4], 10mM MgOAc₂, 10% glycerol, 0.05% Brij 30, 1mM dithiothreitol, 300mM KOAc) and B1000 buffer (25mM Tris-HCl [pH7.4], 10mM MgOAc₂, 10% glycerol, 0.05% Brij 30, 1mM dithiothreitol, 1M KOAc). Purified protein was eluted with B300 buffer containing 5mM biotin, and the protein was concentrated and biotin removed by ultracentrifugation. The protein was estimated to be 95% pure by SDS-PAGE. GTP-binding assays were performed by UV cross-linking purified Nog1NG and [α-³²P]-GTP, recovering the protein by binding to SAM² Biotin Capture Membrane and quantifying the amount of GTP bound using a Phosphorimager. (3804)

Notes: In early stage of Lyme disease in humans, the primary immune response is the production of antibodies to outer surface protein C (OspC). In previous work, the authors demonstrate that the antibody response is specific to the 50 amino acids nearest to the OspC C-terminus. In this study, the authors used smaller OspC fragments of 7 and 16 amino acids to more specifically locate the epitope. Proteins consisting of the final 7 C-terminal amino acids (C7) or 16 C-terminal amino acids (C16) were expressed as biotinylated proteins in E. coli. To purify C7 and C16, the E. coli cultures were sonicated and passed over columns of SoftLink™ Soft Release Avidin Resin at a rate of 0.5ml/minute at 4°C. The captured proteins were analyzed by SDS-PAGE and Western blot analysis using anti-OspC antibodies to confirm protein purity. An affinity column for OspC antibodies was generated by passing biotinylated C7 or C16 over a column of TetraLink™ Tetrameric Avidin Resin, which irreversibly binds biotinylated proteins. Human sera were passed over this column, and the flowthrough fractions were tested in an ELISA to determine the extent to which the OspC antibodies were adsorbed to C7 or C16 fragments. (3663)

Notes: To identify proteins expressed on the cell surface of various strains of Leptospira, the authors labeled intact Leptospira cells with biotin, solubilized the cells with Triton^® X-100, then captured the biotinylated proteins using the SoftLink™ Soft Release Avidin Resin. The captured products were analyzed by one- and two-dimensional gel electrophoresis. The spots were excised and washed with 50mM ammonium bicarbonate /100% acetonitrile. The gel pieces were then dried, rehydrated in a solution containing 12ng of Sequencing Grade Modified Trypsin, and incubated in 50mM ammonium bicarbonate overnight at 37°C. The proteins were concentrated, desalted and subjected to MALDI-TOF mass spectrometry to identify the individual proteins of the Leptospira surfaceome. (3661)

Notes: These authors investigated the relationship between the CD3zeta protein and the TCRαβCD3εδγ complex after T-cell activation. Several of the mutant CD3zeta coding sequences used in these studies were cloned into the pCI-neo Mammalian Expression Vector, and T-cell hybridomas were transfected with these constructs to express mutant proteins. The amounts of CD3 associated with the TCRαβCD3εδγ complex at the cell surface was quantitated by biotinylating cell-surface proteins, purifying the biotinylated proteins with the SoftLink™ Soft Release Avidin Resin, immunoprecipitating the complex with an anti-TCR-Cβ antibody, then detecting the protein by Western blot analysis using a streptavidin-alkaline phosphatase conjugate. (3662)

Notes: Researchers used PCR primers with Kpn I and Hind III restriction sites to clone human IL-2 from a known rhIL-2 E. coli clone containing the PTCGF-11 vector. The PCR product was digested with Kpn I and Hind III and cloned into the PinPoint™ Xa-3 Vector. Transformed E. coli JM109 clones were then pre-incubated in the presence of 8μM biotin for 2 hours before being induced with 100μM IPTG for an additional 2 hours. After induction, the cells were collected and resuspended in a lysis buffer before mechanical lysis with a French press. The lysate was then passed over a SoftLink™ Soft Release Avidin Resin column and the biotinylated rhIL-2 eluted. The resultant purified biotinylated rhIL-2 displayed similar properties and biological activity to native IL-2. Elutants from cells transformed with the PinPoint™ Xa Control Vector produced no biotinylated rhIL-2 and did not display any properties indicating that IL-2 was present. (2680)

Notes: The authors used the PinPoint™ Xa-1 Vector to clone two herpes simplex virus (HSV) genes and express the encoded proteins, IE63 and thymidine kinase, in E. coli JM109 for use as immunogens. Proteins expressed from the PinPint™ Vectors have a biotinylated tag, and the authors used this tag to purify the HSV proteins using the SoftLink™ Soft Release Avidin Resin. In a large-scale purification, the typical yield of IE63 protein was ~650µg/L. The recommended PinPoint™ purification protocol was modified in several ways: 1) the optimal incubation temperature and time for protein induction in E. coli cultures was chosen based on JM109 growth curves; 2) the post-induction time was optimized by monitoring protein expression levels using Western blot analysis; 3) the length of time that proteins were allowed to bind to the SoftLink™ Resin was optimized. The authors found that shortening the length of binding time to 2 hours eliminated the co-purification of endogenous biotinylated proteins in E. coli. (3850)

Notes: Chloroplast processing enzyme (CPE), was expressed in E. coli as a biotinylated fusion protein, and biotinylation was demonstrated using Promega's SoftLink™ Soft Release Avidin Resin. The singly-biotinylated protein was immobilized onto Streptavidin MagneSphere^® Paramagnetic Particles. The immobilized CPE was incubated with the [³⁵S]Methionine-labeled preribulose-1,5-bisphosphate carboxylase/oxygenase activase (preRBCA) and the processed RBCA protein was detected by autoradiography. To further demonstrate the processing, unlabeled preRBCA was processed with the immobilized CPE and the resulting RBCA was analyzed by N-terminal sequencing. The labeled pRBCA was generated with the Rabbit Reticulocyte Lysate System. (0515)

Notes: The authors used the SoftLink™ Soft Release Avidin Resin to isolate E2F with or without bound Rb, p107, or p130 from quiescent or activated Daudi cell extracts using a biotinylated WT E2F DNA binding site. The extract was precleared of non-specific DNA binding proteins first using a biotinylated mutant E2F DNA binding site. (0261)

Notes: The PinPoint™ Protein Purification System was used to express a 178 kDa protein. The protein was expressed, purified on the SoftLink™ Avidin and the purification tag cleaved with Factor Xa. (0563)

Notes: The authors used rhFGF, Basic, and anti-acidic FGF antibody (antibody has been discontinued) to analyze the effect of these factors on the activity of angiogenin on endothelial cells. They also labeled surface molecules of endothelial cells with biotin following treatment with angiogenin to aid in purification of angiogenin receptor. Then they took biotin-labeled molecules and purified using SoftLink™ Soft Release Avidin Resin, detected proteins on Western blot using Streptavidin Alkaline Phosphatase, and grew human umbilical arterial endothelial cells on Fibronectin-coated dishes. (1018)

Notes: The authors constructed mutant E. coli lactose permease proteins in expression vectors with a biotin acceptor domain and factor Xa protease recognition sites C-terminal of the E. coli protein. The proteins were expressed in E. coli and the permease was purified from the extracted membranes with the use of the SoftLink™ Soft Release Avidin Resin. (1075)

Notes: The nine carboxyl terminal amino acids of NR2B, a subunit of the NMDA receptor, were fused into the PinPoint™ Xa3 Vector. The protein was expressed in DH5α and purified with the SoftLink™ Soft Release Avidin Resin. The purified protein was used to probe various bacterially-expressed fusion protein immobilized on nitrocellulose. Proteins containing the PDZ3 domain interacted with the biotinylated fusion protein and were visualized with a streptavidin-HRP conjugate. (0670)

Notes: The 273 amino acid prtB cDNA was cloned into the PinPoint™ Xa-3 Vector and expressed in E. coli HB101 cells. The protein was purified using the SoftLink™ Soft Release Avidin Resin. The purified protein was treated with Factor Xa Protease. Both the fusion protein and the Factor Xa cleaved protease were functional enzymes. (1481)