A novel sodium bis(2-ethylhexyl) sulfosuccinate-PAGE system suitable for the separation of small peptides

Oral engineered Bifidobacterium longum expressing rhMnSOD to suppress experimental colitis

In recent years, using genetic engineering and bioengineering techniques, Bifidobacterium as a carrier to express specific functions of the protein or polypeptide, has become a new treatment for disease. Ulcerative colitis (UC) is a type of inflammatory bowel diseases (IBD). Although the cause of this inflammatory disorder is still unknown, a large amount of evidence suggests that ulcerative colitis is associated with increased activity of reactive oxygen species (ROS), manganese superoxide dismutase (MnSOD) is a kind of superoxide dismutase (SOD) has been demonstrated to play a key role in the pathophysiology of colitis. Here, we explored the Bifidobacterium as a drug delivery system to orally deliver a potent anti-inflammatory but poor penetration and stability antioxidant enzymes human MnSOD, transported into cells by a penetratin PEP-1. We constructed an expression vector expressing PEP-1-hMnSOD fusion protein, and successfully expressed hMnSOD fusion protein in engineered Bifidobacterium. Then we identified the bioactivity of engineered Bifidobacterium in LPS-induced inflammatory cell model. Finally, we used Bifidobacterium expressing PEP-1-hMnSOD fusion protein against DSS-induced ulcerative colitis mice. B. longum-PEP-1-rhMnSOD can successfully express rhMnSOD in the colon. We found that levels of inflammatory cytokines TNF-α, IL-1β, IL-6 and IL-8 as well as histological damage in colonic tissues showed that engineered Bifidobacterium effectively reduced dextran sulfate sodium(DSS)-induced ulcerative colitis, we also tested the MPO, verified the above conclusions. These results suggest that oral Bifidobacterium expressing PEP-1-hMnSOD fusion protein can be treated as a new method of UC treatment.

Oral delivery of Bifidobacterium longum expressing α-melanocyte-stimulating hormone to combat ulcerative colitis

α-Melanocyte-stimulating hormone (α-MSH) is a tridecapeptide derived from pro-opiomelanocortin that exhibits potent anti-inflammatory properties by regulating the production of inflammatory mediators. This peptide has been well established in several inflammatory models, including inflammatory bowel disease (IBD). However, its extremely short duration in vivo limits its clinical application. To address this limitation, Bifidobacterium was used here as a carrier to deliver α-MSH. We utilized α-MSH-engineered Bifidobacterium against IBD, which is closely linked to immune and intestinal microbiota dysfunction. First, we constructed a Bifidobacterium longum secreting α-MSH (B. longum-α-MSH). We then tested the recombinant α-MSH expression and determined its bioactivity in HT-29 cells. To assess its effectiveness, B. longum-α-MSH was used against an ulcerative colitis (UC) model in rats induced by dextran sulfate sodium. The data showed that α-MSH expression in B. longum-α-MSH was effective, and its biological activity was similar to the synthesized one. This UC model experiment indicated that B. longum-α-MSH successfully colonized the intestinal gut, expressed bioactive α-MSH and had a significant anti-inflammatory effect. The results demonstrate the feasibility of preventing IBD by using B. longum-α-MSH.

High-resolution Native-PAGE for membrane proteins capable of fluorescence detection and hydrodynamic state evaluation

An improved native polyacrylamide gel electrophoresis (PAGE) method capable of evaluating the hydrodynamic states of membrane proteins and allowing in-gel fluorescence detection was established. In this method, bis(alkyl) sulfosuccinate is used to provide negative charges for detergent-solubilized membrane proteins to facilitate proper electrophoretic migration without disturbing their native hydrodynamic states. The method achieved high-resolution electrophoretic separation, in good agreement with the elution profiles obtained by size exclusion chromatography. The applicability of in-gel fluorescence detection for tagged green fluorescent protein (GFP) facilitates the analysis of samples without any purification. This method might serve as a general analytical technique for assessing the folding, oligomerization, and protein complex formation of membrane proteins.

SARCOSYL-PAGE: a new method for the detection of MIRCERA- and EPO-doping in blood

The detection of doping with MIRCERA (the brand name for Continuous Erythropoietin Receptor Activator, or CERA) is hampered by the limited excretion of the rather large molecule (approximately 60 kDa) in urine. Blood (serum, plasma) in combination with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) appears to be the ideal matrix for detecting all forms of doping with erythropoiesis-stimulating agents (ESAs) because the apparent molecular masses of ESAs are different from the mass of human serum erythropoietin (shEPO). While SDS-PAGE has proven the most sensitive method for the detection of doping with Dynepo, the sensitivity of SDS-PAGE for MIRCERA is drastically decreased. By exchanging the SDS for SARCOSYL (SAR) in the sample and running buffers the sensitivity problem was solved. SARCOSYL, a methyl glycine-based anionic surfactant, is only binding to the protein-part of MIRCERA but not to its polyethylene glycol (PEG)-chain, while SDS binds to both parts. In consequence, the monoclonal anti-EPO antibody (clone AE7A5) no longer interacts with the fully SDS-solubilized MIRCERA molecules. Only those molecules that contain SDS bound to the protein-chain are detected. Due to the inability of SARCOSYL to solubilize PEG-molecules, MIRCERA can be detected on SARCOSYL-PAGE with the same sensitivity as non-PEGylated epoetins. In a typical SAR-PAGE experiment, 200 microL of serum are used, which allows the direct detection of MIRCERA, recombinant epoetins (such as NeoRecormon, Dynepo, NESP), and shEPO in a single experiment and with high (i.e. femtogram) sensitivity.