OBJECTIVETo construct vitiligo-specific HLA-A*0201-peptide tetramers and to apply the constructed tetramers in detection of vitiligo-specific cytotoxic T lymphocytes (CTL).

METHODSProteins HLA-A0201*-BSP and β2M were obtained by effective prokaryotic expression. The purified proteins were refolded with vitiligo antigen peptides MelanA 26-35, gp100 209-217, and tyrosinase 1-9, respectively to form HLA-A*0201-peptide complex. The complex was biotinylated by BirA enzyme and purified by gel-filtration chromatography. The tetramers were generated by mixing the complex with phycoerythrin (PE)-streptavidin at a ratio of 4∶1 and identified by Dot-blot assay. The capacity of tetramer to detect vitiligo-specific CTL was analyzed by flow cytometry.

RESULTSThe biotinylation of vitiligo-specific HLA-A*0201-peptide tetramers were successfully performed by Dot-blot. Flow cytometry analysis indicated that the tetramer effectively bound to specific CTL from peripheral blood of patients with vitiligo.

CONCLUSIONThree kinds of biotinylated vitiligo-specific HLA-A*0201-peptide tetramers have been constructed successfully. The tetramer can detect antigen specific CTL from patients with vitiligo.

Biotinylation ; Flow Cytometry ; HLA-A2 Antigen ; Humans ; Peptides ; T-Lymphocytes, Cytotoxic ; cytology ; Vitiligo ; diagnosis ; immunology

PURPOSE: Porphyromonas gingivalis and Tannerella forsythia have been implicated as the major etiologic agents of periodontal disease. These two bacteria are frequently isolated together from the periodontal lesion, and it has been suggested that their interaction may increase each one's virulence potential. The purpose of this study was to identify proteins on the surface of these organisms that are involved in interbacterial binding. METHODS: Biotin labeling of surface proteins of P. gingivalis and T. forsythia and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was performed to identify surface proteins involved in the coaggregating activity between P. gingivalis and T. forsythia. RESULTS: It was found that three major T. forsythia proteins sized 161, 100, and 62 kDa were involved in binding to P. gingivalis, and P. gingivalis proteins sized 35, 32, and 26 kDa were involved in binding to T. forsythia cells. CONCLUSIONS: LC-MS/MS analysis identified one T. forsythia surface protein (TonB-linked outer membrane protein) involved in interbacterial binding to P. gingivalis. However, the nature of other T. forsythia and P. gingivalis surface proteins identified by biotin labeling could not be determined. Further analysis of these proteins will help elucidate the molecular mechanisms that mediate coaggregation between P. gingivalis and T. forsythia.
Bacteria ; Bacterial Outer Membrane Proteins ; Biotin ; Biotinylation ; Forsythia* ; Mass Spectrometry ; Membrane Proteins ; Membranes ; Periodontal Diseases ; Periodontitis ; Porphyromonas gingivalis* ; Porphyromonas* ; Virulence

OBJECTIVETo investigate single-molecule detection and characterization of DNA replication.

METHODSSingle-stranded DNA (ssDNA) as the template of DNA replication was attached to DNA origami by a hybridization reaction based on the complementary base-pairing principle. DNA replication catalyzed by E.coli DNA polymerase I Klenow Fragment (KF) was detected using atomic force microscopy (AFM). The height variations between the ssDNA and the double-stranded DNA (dsDNA), the distribution of KF during DNA replication and biotin-streptavidin (BA) complexes on the DNA strand after replication were detected. Agarose gel electrophoresis was employed to analyze the changes in the DNA after replication.

RESULTSThe designed ssDNA could be anchored on the target positions of over 50% of the DNA origami. The KF was capable of binding to the ssDNA fixed on DNA origami and performing its catalytic activities, and was finally dissociated from the DNA after replication. The height of DNA strand increased by about 0.7 nm after replication. The addition of streptavidin also resulted in an DNA height increase to about 4.9 nm due to the formation of BA complexes on the biotinylated dsDNA. The resulting dsDNA and BA complex were subsequently confirmed by agarose gel electrophoresis.

CONCLUSIONSThe combination of AFM and DNA origami allows detection and characterization of DNA replication at the single molecule level, and this approach provides better insights into the mechanism of DNA polymerase and the factors affecting DNA replication.

Biotinylation ; DNA ; chemistry ; DNA Replication ; DNA, Single-Stranded ; chemistry ; DNA-Directed DNA Polymerase ; Electrophoresis, Agar Gel ; Microscopy, Atomic Force ; Nucleic Acid Hybridization ; Streptavidin

The aim was to develop a single multiple-epitope fusion antigen which incorporates all of the major immunodominant epitopes from the six functional regions of the HCV genome. A nucleic acid sequence consisting of viral core, E1, E2, NS3, NS4, and NS5 regions was constructed and inserted into the Promega Pinpoint Xa-1 T vector for inducing expression. The protein was expressed in JM109 (DE3) as a fusion protein with a 13 kD biotinlated tag to be used for detection and affinity purification. Immunogenicity and biotinylated tag of the fusion protein were detected by Western blot analysis with positive anti-HCV serum and streptavidin alkaline phosphatase. After purified by Promega SoftLink Soft Release Avidin Resin, the protein was pre-coated on microwell and detected with anti-core, anti-NS3, anti-NS4 and anti-NS5 positive sera by EIA, respectively. The results indicated that the recombinant soluble protein was expressed and labelled with biotin successfully, it reacted with anti-HCV positive serum, and exposed all of the major immunogenic epitopes chosen. In conclusion, this recombinant antigen may be used to design an double antigen sandwich anti-HCV immunoassay.
Antigens, Viral ; genetics ; immunology ; Biotinylation ; Cloning, Molecular ; Enzyme-Linked Immunosorbent Assay ; Hepacivirus ; immunology ; Hepatitis C Antibodies ; blood ; Humans ; Immunodominant Epitopes ; Recombinant Fusion Proteins ; genetics ; immunology

OBJECTIVETo prepare streptavidin-tagged human interferon-inducible T cell alpha chemoattractant bifunctional fusion proteins (SA/hI-TAC) and evaluate its biological activity.

METHODSpET24a-SA-hI-TAC/pET21a-hI-TAC-SA plasmids were constructed and expressed in BL21. SA-hI-TAC and hI-TAC-SA fusion proteins were purified by Ni-NTA affinity chromatography, refolded by dialysis and identified by Western blotting. The bifunctionality of the fusion proteins (biotin-binding function and hI-TAC activity) was analyzed by flow cytometry and lymphocyte chemotaxis experiment, respectively.

RESULTSSA-hI-TAC/hI-TAC-SA fusion proteins were expressed at about 12% and 25% of the total bacterial protein, respectively. The two fusion proteins had a purity of about 85% and 90% after purification, and their purity reached 98% after purification with S-100 gel filtration chromatography. Both of the fusion proteins were efficiently immobilized on the surface of biotinylated mouse bladder cancer MB49 cells (91.3% for SA-hI-TAC and 98.8% for hI-TAC-SA). SA/hI-TAC induced lymphocyte chemotaxis in a dose-dependent manner, and hI-TAC-SA showed a stronger chemotactic effect than SA-hI-TAC.

CONCLUSIONSWe successfully obtained SA/hI-TAC bifunctional fusion proteins, which may potentially be used in local treatment of tumor and as a tumor vaccine.

Animals ; Biotinylation ; Blotting, Western ; Cancer Vaccines ; Cell Line, Tumor ; Chemokine CXCL11 ; chemistry ; Chromatography, Affinity ; Humans ; Interferons ; chemistry ; Mice ; Plasmids ; Recombinant Fusion Proteins ; biosynthesis ; chemistry ; Streptavidin

Multidrug resistance 3 (MDR3) is expressed on the canalicular membrane of the hepatocytes and plays an important role in protecting the liver from bile acids. Altered ABCB4 gene expression can lead to a rare hepatic disease, low phospholipid-associated cholelithiasis (LPAC). In this study, we characterized 3 ABCB4 mutations in LPAC patients using various in vitro assay systems. We first measured the ability of each mutant to transport paclitaxel and then the mechanisms by which these mutations might change MDR3 transport activity were determined using immunoblotting, cell surface protein biotinylation, and immunofluorescence. Through a membrane vesicular transport assay, we observed that the uptake of paclitaxel was significantly reduced in membrane vesicles expressing 2 ABCB4 mutations, F165I and S320F. Both mutants showed significantly decreased total and cell surface MDR3 expression. These data suggest two missense mutations of ABCB4 may alter function of MDR3 and ultimately can be determined as LPAC-causing mutations.
Bile Acids and Salts ; Biotinylation ; Cholelithiasis* ; Drug Resistance, Multiple ; Fluorescent Antibody Technique ; Gene Expression ; Hepatocytes ; Humans ; Immunoblotting ; Liver ; Membranes ; Mutation, Missense ; Paclitaxel

OBJECTIVETo clarify the binding character between Beta-2-glycoprotein I (Beta-2-GPI) and HBsAg.

METHODSBeta-2-GPI was purified from human plasma and labelled with biotin. Solid phase enzyme linked absorbance assay was used to investigate its binding with HBsAg.

RESULTSBiotinylated Beta-2-GPI was found to bind HBsAg and the reaction could be inhibited by excess unlabelled Beta-2-GPI.

CONCLUSIONSBeta-2-GPI may play a role in hepatitis B virus infection.

Binding Sites ; Biotinylation ; Enzyme-Linked Immunosorbent Assay ; methods ; Glycoproteins ; isolation & purification ; metabolism ; Hepatitis B Surface Antigens ; metabolism ; Hepatitis B virus ; chemistry ; metabolism ; Humans ; beta 2-Glycoprotein I

To investigate the interaction between tumor necrosis factor alpha (TNF alpha) mimotopes and TNF alpha-binding peptides screened from random phage display peptide library with TNF alpha mimotopes displayed on phage clone as the target, the computational docking program AutoDock (with confirmation calculations using Discover) was used to predict and analyze the binding modes of LLT-18 (TNF alpha binding peptide, sequence EHMALTYPFRPP) with TNF alpha, after which LCS-7 (TNF alpha mimic phage clone, displayed positive sequence c-RRPAQSG-c) was docked to LLT-18 manually. The binding between LLT-18 and TNF alpha or LCS-7 was stabilized predominantly through electrostatic interaction and H-bond formation. The Arg residues in TNF alpha or LCS-7 were important for their interaction with LLT-18. For LLT-18, the key amino acid residues were Glu1, His2, Met3 and Tyr7. These results suggest the feasibility of screening ligand to single epitope with specific phage clone as the target, and of predicting the interaction between small peptides by computer-aided molecular modeling.
Amino Acid Sequence ; Animals ; Antibodies, Monoclonal ; immunology ; Biotinylation ; Computer Simulation ; Drug Evaluation, Preclinical ; methods ; Epitopes ; immunology ; Humans ; Ligands ; Models, Molecular ; Oligopeptides ; chemistry ; metabolism ; Peptide Library ; Protein Conformation ; Solubility ; Tumor Necrosis Factor-alpha ; chemistry ; immunology ; metabolism

Biotinylated chitosan nanoparticles (Bio-CS-NP) were prepared for the active delivery to cancer cells and its characterization was investigated in this study. The preparation process included two steps. First, biotinylated chitosan ( Bio-CS ) was obtained through a reaction between sulfosuccinimidobiotin and chitosan (CS). Second, Bio-CS-NP were prepared by the precipitation of Bio-CS with sodium chloride solution. With a biotin reagent box, the conjugation densities of biotin on the surface of Bio-CS-NP were determined. The morphology and diameter of the nanoparticles were assayed by transmission electron microscope (TEM) and laser light scattering particle analyzer, respectively. The uptake of nanoparticles by human hepotacarcinoma HepG2 cells, for example, Bio-CS-NP and chitosan nanoparticles (CS-NP) without any modification, was quantitatively examined. The results indicated that the conjugation densities of biotin on the surface of Bio-CS-NP were 2.2 biotin CS. Bio-CS-NP were spherical, smooth on the surface. The average diameter was 296.8 nm. The polydispersion index was 0.155. The uptake of Bio-CS-NP by HepG2 cells was much higher than that of CS-NP (P < 0.05). It demonstrated that Bio-CS-NP can be applied as a new vehicle to actively deliver anticancer drugs to tumor cells. The method for the determination of biotin was simple and practical.
Biotin ; analogs & derivatives ; chemistry ; metabolism ; Biotinylation ; Carcinoma, Hepatocellular ; metabolism ; pathology ; Cell Line, Tumor ; Chitosan ; chemistry ; metabolism ; Drug Carriers ; Drug Compounding ; Drug Delivery Systems ; Humans ; Liver Neoplasms ; metabolism ; pathology ; Nanoparticles ; Particle Size ; Succinimides ; chemistry ; metabolism

BACKGROUND AND OBJECTIVEIntravesical administration of Bacillus Calmette-Guerin (BCG) after transurethral resection is by far the most effective local therapy for superficial bladder cancer, the fifth most common cancer in the world. However, approximately one-third of patients fail to respond and most patients eventually relapse. In addition, there are pronounced side effects of BCG therapy, such as BCG sepsis and a high frequency of BCG-induced cystitis. This study established a novel immunotherapy through immobilization of streptavidin-tagged human IL-2 (SA-hIL-2) on the biotinylated mucosal surface of bladder wall.

METHODSA mouse orthotopic model of MB49 bladder cancer was established by perfusing MB49 cells into mouse bladders. The SA-hIL-2 fusion protein was immobilized on the biotinylated mucosal surface of the bladder wall. Treatment began on day 1 after MB49 implantation, once every 3 days for 6 times. Immunohistochemical assay was performed to assess the persistence of SA-hIL-2 immobilized on the biotinylated mucosal surface of the bladder wall. The mice were monitored for tumor growth and survival. On day 60 after MB49 implantation, the SA-hIL-2-cured mice, which were found to have no hematuria or palpable tumors, were challenged with wild-type MB49 cells implanted into the pretreated bladder and monitored for survival.

RESULTSSA-hIL-2 could be immobilized efficiently and durably on the bladder mucosal surface as long as 7 days. On day 60 after MB49 implantation, 9 out of 20 SA-hIL-2-treated mice survived, but all mice in PBS control group died. More importantly, 5 out of 9 tumor-free mice in the SA-hIL-2 group were protected against a second intravesical wild-type MB49 tumor challenge.

CONCLUSIONSSA-hIL-2 fusion protein could significantly inhibit tumor growth and extend the survival time in the orthotopic model of MB49 bladder cancer.

Animals ; Biotinylation ; Cell Line, Tumor ; Female ; Immobilized Proteins ; metabolism ; therapeutic use ; Immunotherapy ; methods ; Interleukin-2 ; metabolism ; therapeutic use ; Mice ; Mice, Inbred C57BL ; Mucous Membrane ; metabolism ; Neoplasm Transplantation ; Receptors, Interleukin-2 ; metabolism ; Recombinant Fusion Proteins ; metabolism ; therapeutic use ; Streptavidin ; metabolism ; therapeutic use ; Urinary Bladder ; pathology ; Urinary Bladder Neoplasms ; immunology ; therapy