After cell lysis, my mass spectrometry sample is very viscous and difficult to pipette. How do I reduce the sample viscosity?
High sample viscosity after lysis is due to release of DNA from the nucleus. Sonication or addition of a nuclease such as the Pierce Universal Nuclease (Cat. No. 88700, 88701, or 88702) can be used to degrade DNA and reduce sample viscosity.
Can you explain how the B-PER Bacterial Protein Extraction Reagent lyses cells?
The B-PER Reagent solution contains a proprietary, mild, non-ionic detergent in 20 mM Tris-HCl, pH 7.5. It effectively disrupts cells and solubilizes native or recombinant proteins without denaturation. The reagent creates holes in the cell membrane that will leak out cytosolic proteins. The sample may become very viscous when the bacterial chromosome is released. We recommend adding DNAse I (Cat. No. 90083) to the reagent to reduce viscosity. For better lysis efficiency and if there are inclusion bodies, we recommend adding Lysozyme (Cat. No. 90082) to the reagent. Alternatively, you may purchase the B-PER Bacterial Protein Extraction Reagent with Enzymes Kit (Cat. No. 90078 or 90079) that includes the B-PER Bacterial Protein Extraction Reagent, DNase I, and Lysozyme.
Validation of an IFN-gamma ELISpot assay to measure cellular immune responses against viral antigens in non-human primates.
Authors:Yang F,Patton K,Kasprzyk T,Long B,Gupta S,Zoog SJ,Tracy K,Vettermann C
Journal:Gene therapy
PubMed ID:33432123
Adeno-Associated Virus (AAV)-based gene therapy vectors are in development for many inherited human disorders. In nonclinical studies, cellular immune responses mediated by cytotoxic T cells may target vector-transduced cells, which could impact safety and efficacy. Here, we describe the bioanalytical validation of an interferon-gamma (IFN-γ)-based Enzyme-Linked Immunospot (ELISpot) assay for ... More
Characterization of an expanded set of assays for immunomodulatory proteins using targeted mass spectrometry.
Immunotherapies are revolutionizing cancer care, but many patients do not achieve durable responses and immune-related adverse events are difficult to predict. Quantifying the hundreds of proteins involved in cancer immunity has the potential to provide biomarkers to monitor and predict tumor response. We previously developed robust, multiplexed quantitative assays for ... More
PhoXplex: Combining Phospho-enrichable Cross-Linking with Isobaric Labeling for Quantitative Proteome-Wide Mapping of Protein Interfaces.
Integrating cross-linking mass spectrometry (XL-MS) into structural biology workflows provides valuable information about the spatial arrangement of amino acid stretches, which can guide elucidation of protein assembly architecture. Additionally, the combination of XL-MS with peptide quantitation techniques is a powerful approach to delineate protein interface dynamics across diverse conditions. While ... More
An efficient and cost-effective purification protocol for Staphylococcus aureus Cas9 nuclease.
Here, we describe a protocol for purifying functional clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) from Staphylococcus aureus within 24 h and over 90% purity. SaCas9 purification begins with immobilized metal affinity chromatography, followed by cation exchange chromatography, and ended with centrifugal concentrators. The simplicity, cost-effectiveness, and reproducibility ... More
p53 is active in murine stem cells and alters the transcriptome in a manner that is reminiscent of mutant p53.
Authors:Yan H, Solozobova V, Zhang P, Armant O, Kuehl B, Brenner-Weiss G, Blattner C
Journal:
PubMed ID:25719246
Since it was found that p53 is highly expressed in murine embryonic stem cells, it remained a mystery whether p53 is active in this cell type. We show that a significant part of p53 is localised in the nucleus of murine embryonic stem cells and that the majority of this ... More