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34 protocols using vivaspin 500

1

Radiolabeling and Imaging of Anti-IFNγ Antibody

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Radiochemistry of anti-mouse-IFNγ (clone AN18, Thermo Fisher Scientific) and IgG1 isotype control anti-horseradish peroxidase (clone HRPN, BE0088, BioXCell) was performed as described previously (22 (link), 26 (link)). All antibodies were conjugated to p-SCN-Bn-Desferrioxamine (DFO) with a 1:5 mole ratio of mAb : DFO in saline at pH ~9 for 1hr at 37°C. Unbound DFO was removed via spin column centrifugation (MWCO: 30 kDa, GE Vivaspin 500). 89Zr (3D Imaging) was incubated with the mAb-DFO conjugates at pH ~ 7.2-7.4 at room temperature for 1hr. Unbound 89Zr was removed via spin column centrifugation (MWCO: 30 kDa, GE Vivaspin 500) using saline as eluent buffer. [89Zr]Zr-DFO-anti-IFNγ and [89Zr]Zr-DFO-IgG were each labeled at a specific activity of ~5 mCi/mg. Radiochemical yields of both constructs were >95% as determined via radio-instant thin layer chromatography (iTLC, Eckert & Ziegler). Tumor-bearing animals used for imaging were injected i.v. with radiolabeled antibodies (189 ± 31 µCi) in ~150 µL sterile saline. PET images were acquired 72 hrs post-injection on a Bruker Albira SI microPET/CT system. Images were decay corrected and analyzed in PMOD version 4.304. Volume of Interest (VOI) measurements within tumors were used to determine the uptake of the radiotracer, which is expressed as the maximum injected dose per mL (%ID/mL).
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2

Radiolabeled Antibody Development

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All antibodies (Bioxcell) were buffer exchanged in saline prior to conjugation to p-SCN-Bn-deferoxamine (DFO). Antibody tracers were developed following established protocols (23 (link), 24 (link)). Both the murine antibody R2.9A5 (αIL-12) and a control non-specific rat IgG isotype were conjugated with a 1:5 mole ratio of mAb : DFO in saline at pH ~9 for 1 h at 37°C. Unbound DFO was removed via spin column centrifugation (MWCO: 30 kDa, GE Vivaspin 500). 89Zr in oxalic acid (3D Imaging, Little Rock, AR) was incubated with the mAb-DFO conjugates at pH ~ 7.2-7.4 at room temperature. Unbound 89Zr was removed via centrifugation with molecular weight column filters (MWCO: 30 kDa, GE Vivaspin 500) using saline as eluent buffer. [89Zr]Zr-DFO-αIL12 was labeled at a specific activity of 259 ± 2.6 MBq/mg (7.01 ± 0.07 mCi/mg) and [89Zr]Zr-DFO-IgG was labelled at a specific activity of 258 ± 1 MBq/mg (6.98 ±0.03 mCi/mg). Radiochemical yields of both constructs were >95% as determined via radio-instant thin layer chromatography (iTLC, Eckert & Ziegler). Stability of the intact [89Zr]Zr-DFO-αIL12 was monitored between 24-96 h post-synthesis in saline at 37°C.
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3

Quantification of Cytochrome C in Cellular Fractions

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The concentration of CytC in cytosolic and mitochondrial fractions was quantitated by solid phase sandwich ELISA (Quantikine ELISA, human Cytochrome C Immunoassay, R&D Systems) as described by the manufacturer. Prior to the assay, fractions containing cytoplasmic proteins were concentrated on Vivaspin 500 centrifugal concentrators (GE HealthCare, molecular weight cut off 5000), mitochondrial pellets were resuspended in Cell Lysis Buffer provided with the kit, and total protein of the respective fractions was evaluated by BCA protein assay (Thermo Fisher Scientific/Pierce). Samples and human CytC standards were diluted in Calibrator Diluent and incubated with microtiter wells pre-coated with a monoclonal antibody specific for human CytC. After washing away unbound proteins, wells were further incubated with an HRP-linked monoclonal antibody anti-human CytC, color developed with tetramethylbenzinine peroxidase substrate, and evaluated through quantitation of the Absorbance at 450 nm. The CytC concentration of the different samples was interpolated from the standard curve with the aid of GraphPad Prism and normalized to the protein content of the respective subcellular fractions.
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4

Activation of Latent AbPPO4 Enzyme

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Latent AbPPO4 was converted into its active form by treatment with proteinase K. The protease was used at a ratio of 1:10 (equivalent to 45 µg of proteinase K per mg of latent AbPPO4) in a reaction buffer containing 50 mM Tris-HCl pH 8 @ 25 °C, 100 mM sodium ascorbate and 20 g l−1 of latent AbPPO4 for a total reaction time of 90 min. The reaction was stopped by addition of 2 mM PMSF after which the solution was concentrated to less than 70 µl by ultrafiltration (Vivaspin® 500, 30 kDa molecular weight cut-off) and applied onto a size exclusion column (Superdex 200 Increase from GE Healthcare) equilibrated with 50 mM sodium citrate pH 6.8 and run with the same buffer at 4 °C and with a flow rate of 0.5 ml min−1. The eluted fractions possessing tyrosinase activity were pooled and concentrated by ultrafiltration (Vivaspin® 500, 30 kDa molecular weight cut-off).
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5

Miniature Gelatin Affinity Chromatography for Gelatinase Purification

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Gelatinase purification was performed by miniature gelatin affinity chromatography [19 (link)]. Briefly, 0.5 mL of pooled sera of five lung cancer patients, diluted with 0.5 mL of 50 mM Tris pH 7.5, 0.6 M NaCl (equilibration buffer), were added to mini-spin columns (Bio-Rad Laboratories, Segrate, MI, Italy) loaded with 0.5 mL gelatin-Sepharose 4B beads (GE Healthcare, Uppsala, Sweden) previously equilibrated with equilibration buffer. The mixture was then equilibrated at 4 °C for 60 min (vortexing every 10 min and reversing the column). Successively, the cap was removed and the unbound sample was removed by centrifugation at 3000× g (Amicon MC-13 microcentrifuge; Millipore, Bedford, MA, USA), for 2 min. Beads were washed two times with washing buffer 50 mM Tris pH 7.5, 0.1 M NaCl, and gelatinases were eluted with 150 μL of 5% DMSO in 50 mM Tris pH 7.5, 0.1 M NaCl after incubation for 30 min. at room temperature. The eluate was desalted and concentrated to a final volume of 30 μL with 2.0 mL of water in Vivaspin 500 (MWCO 30,000; GE Healthcare, Uppsala, Sweden). A total of 5 µL of purified gelatinase was applied for 2-DZ analysis, whereas 25 µL of sample was subjected to 2-DE analysis for western blot identification of 65 kDa MMP-9 active form.
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6

Stereochemical Analysis of PTE Hydrolysis

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To enable the identification of the specific diastereomer being hydrolyzed by wild-type PTE, G60A-PTE, In1W-PTE and Sb-PTE, the reaction products were interrogated by 31P NMR. Reactions were conducted in a reaction volume of 4.0 mL with 2.0 mM compound 1, 30% methanol, and 50 mM HEPES (pH 8.0). The progress of the reaction was monitored by removing small aliquots and measurement of the absorbance at 400 nm. At various time points, 1.0 mL samples were removed from the reaction mixture, and the enzyme removed by ultrafiltration using a Vivaspin 500 (GE Healthcare) centrifugal filtration device. The sample was brought to 10 mM EDTA in 20% D2O and the 31P NMR spectrum obtained using a sample volume of 750 μL.
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7

N-Glycan Release and Characterization from gp120

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N-glycans were released from 150 μg recombinant gp120 (JRCSF) by incubation with PNGase F(New England BioLabs) according to manufacturer’s protocol. Glycans were separated from the protein by spin-filtration through 5000 Da MWCO filter (Vivaspin, GE Healthcare) and speedvac dried. Released glycans were 2-AB labelled as described previously (Struwe and Rudd, 2012 (link)). Briefly, glycans were incubated with 20 μL 1 % formic acid for 45 min at room temperature, and dried before addition of 5 μL 2-AB labelling solution (DMSO:glacial acetic acid (7:3 v/v), 1M sodium cyanoborohydride, 0.5 M anthranilamide (2-AB)), followed by incubation for 3 h at 65 °C. Excess dye was removed by purification with PhyNexus normal phase columns, equilibrated with 95% acetonitrile and eluted with 20% acetonitrile. 2-AB labelled glycans were incubated with BanLec for 1 h at 37°C for the depletion assays. Unbound 2-AB labelled glycans were separated from BanLec-glycan complexes using Vivaspin 500, 5000 Da MWCO spin columns (GE Healthcare). Glycans were dried and resuspended in 30 μL 65% CAN prior to analysis using a LudgerSep N2 amide HPLC column (Ludger Ltd). Each HPLC injection consisted of N-glycans released from 10 μg gp120. Analysis was performed using a Waters Acquity system with Empower software.
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8

Purification and storage of antibodies

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For experiments in Fig. 8b and d and Extended Data Fig. 9bd, polyclonal rabbit IgG control (Abcam, cat. no. AB171870) and polyclonal rabbit α-IGFBP3 Ab (Abcam, cat. no. AB76001) were stored at 4 °C until use. To avoid freeze/thaw cycling and remove stabilizing excipients such as azides, prior to application to cultured tissue or cells, an appropriate quantity of antibody was washed 5 times with a 5x volume of sterile PBS using 5 kD size-exclusion columns (Vivaspin 500, GE Healthcare, cat. no. 28-9322-23) in a 4 °C microcentrifuge (12,000 RCF, 15 min), resuspended in PBS to a final concentration of 1 μg/μl, and stored at 4 °C until use for no more than 24 h. For experiments in Fig. 8e, recombinant α-Igfbp3 Ab (Abcam, cat. no. AB224530; clone: EPR18680-153 without carrier) or polyclonal rabbit IgG control (Abcam, cat. no. AB171870) were purified as above on receipt, and stored in individual aliquots at −20 °C to avoid freeze-thaw effects. For experiments in Fig. 7df, polyclonal rabbit IgG control (Abcam, cat. no. AB171870) and recombinant α-Igfbp3 Ab (Abcam, cat. no. ab193910; clone: EPR18680–153 with carrier) were purified as above on receipt, and stored in individual aliquots at −20 °C to avoid freeze-thaw effects.
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9

Microalgal Cell Concentration and Extraction

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Cells were grown in 200 mL of BG-11 to an OD of 0.8. They were then centrifuged at 2760 g for 8 min and the supernatant was discarded. The cell pellet was then re-suspended in 5 mL of BG-11. The cell suspension was subjected to 2 min of thorough vortexing followed by another centrifugation at 2760 g for 8 min. The supernatant was carefully removed without disrupting the cell pellet and concentrated using a Vivaspin 500 column with a 5 kDa molecular weight cut off (GE Healthcare, UK) to a final volume of 50 µL.
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10

Visualizing DENV2 Viral Particles

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Msq-DENV2-P1 at 107 PFU was fixed with the same volume of 4% paraformaldehyde overnight. The next day, the viral samples were 10-fold-concentrated with Vivaspin 500 (3 kDa MWCO; GE Healthcare) by centrifugation at 13,500 g at 4°C for 30 min. To negative stain, 10 μl of the concentrated viral sample was aspirated onto mesh nickel grids (FCF300-Ni, Electron Microscopy Sciences), followed by staining with 40 μl of 2% uranyl acetate for 30 sec. Images were viewed with a Hitachi H-7650 transmission electron microscope (TEM) using an accelerating voltage of 120 kV. The size of viral particles was quantified by ImageJ software.
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