SDS-PAGE to Immunoblot in One Hour

In Vitro Biochemical Characterization of Excised Macrocyclizing Thioesterase Domains from Non-ribosomal Peptide Synthetases

Characterization of thioesterases (TEs) is an important step in understanding natural product biosynthesis. Studying non-ribosomal peptide synthetase (NRPS) TEs presents a unique set of challenges with specific cloning and expression issues as well as the challenging synthesis of the thioester peptides substrate required for characterization of the TE. In this method, we describe the cloning and expression of NRPS TEs, the synthesis of thioester peptides, and the in vitro biochemical characterization of the enzyme.

Under-5-Minute Immunoblot Assays by Vortex Fluidic Device Acceleration

Unlocking the potential of personalized medicine in point-of-care settings requires a new generation of biomarker and proteomic assays. Ideally, assays could inexpensively perform hundreds of quantitative protein measurements in parallel at the bedsides of patients. This goal greatly exceeds current capabilities. Furthermore, biomarker assays are often challenging to translate from benchtop to clinic due to difficulties achieving and assessing the necessary selectivity, sensitivity, and reproducibility. To address these challenges, we developed an efficient (<5 min), robust (comparatively lower CVs), and inexpensive (decreasing reagent use and cost by >70 %) immunoassay method. Specifically, the immunoblot membrane is dotted with the sample and then developed in a vortex fluidic device (VFD) reactor. All assay steps-blocking, binding, and washing-leverage the unique thin-film microfluidics of the VFD. The approach can accelerate direct, indirect, and sandwich immunoblot assays. The applications demonstrated include assays relevant to both the laboratory and the clinic.

Artifacts and Common Errors in Protein Gel Electrophoresis

In spite of taking precautions, some common mistakes creep into well-planned gel electrophoresis experiments. This occurs commonly in relation to calculating the cross-linking factor of a gel, polymerization temperature and time for a polyacrylamide gel, inducing aggregates in samples for electrophoresis, titrating the running buffer in electrophoresis, proper sample preparation, amount of protein to be loaded on a gel, sample buffer-to-protein ratios, incompletely removing phosphate-buffered saline from cells prior to cell lysis, and over-focusing of IPG strip in two-dimensional gel electrophoresis. In addition, subtle artifacts can have significant deleterious effects on carefully planned and executed experiments. Proteases that act at room temperature upon proteins in the sample buffer prior to heating, cleavage of the Asp-Pro bond upon prolonged heating of proteins at high temperatures, contamination of sample or sample buffer with keratin, leaching of chemicals from disposable plastic ware, and contamination of urea with ammonium cyanate are some of the common reasons for artifacts in gel electrophoresis. Taking proper heed to all these factors can greatly help generate good experimental results.

Ultrarapid Sodium Dodecyl Sulfate Polyacrylamide Mini-Gel Electrophoresis

We describe here an ultrafast method for electrophoresing proteins on SDS-PAGE. Previously we reported a method to complete SDS-PAGE and immunoblotting in an hour, including electrophoresing proteins at 70°C in 10 min. Here we show that we can electrophorese molecular weight standards and bovine serum albumin on a 4-20% gradient gel in well under 10 min using heated (44 °C) Laemmli running buffer and high voltage.

An overview of technical considerations for Western blotting applications to physiological research

The applications of Western/immunoblotting (WB) techniques have reached multiple layers of the scientific community and are now considered routine procedures in the field of physiology. This is none more so than in relation to skeletal muscle physiology (i.e., resolving the mechanisms underpinning adaptations to exercise). Indeed, the inclusion of WB data is now considered an essential aspect of many such physiological publications to provide mechanistic insight into regulatory processes. Despite this popularity, and due to the ubiquitous and relatively inexpensive availability of WB equipment, the quality of WB in publications and subsequent analysis and interpretation of the data can be variable, perhaps resulting in spurious conclusions. This may be due to poor laboratory technique and/or lack of comprehension of the critical steps involved in WB and what quality control procedures should be in place to ensure robust data generation. The present review aims to provide a detailed description and critique of WB procedures and technicalities, from sample collection through preparation, blotting and detection, to analysis of the data collected. We aim to provide the reader with improved expertise to critically conduct, evaluate, and troubleshoot the WB process, to produce reproducible and reliable blots.