Gasotransmitters in the tumor microenvironment: Impacts on cancer chemotherapy (Review).

Nitric oxide, carbon monoxide and hydrogen sulfide are three endogenous gasotransmitters that serve a role in regulating normal and pathological cellular activities. They can stimulate or inhibit cancer cell proliferation and invasion, as well as interfere with cancer cell responses to drug treatments. Understanding the molecular pathways governing the interactions between these gases and the tumor microenvironment can be utilized for the identification of a novel technique to disrupt cancer cell interactions and may contribute to the conception of effective and safe cancer therapy strategies. The present review discusses the effects of these gases in modulating the action of chemotherapies, as well as prospective pharmacological and therapeutic interfering approaches. A deeper knowledge of the mechanisms that underpin the cellular and pharmacological effects, as well as interactions, of each of the three gases could pave the way for therapeutic treatments and translational research.

Efficient removal of dyes and proteins by nitrogen-doped porous graphene blended polyethersulfone nanocomposite membranes.

Nitrogen-doped porous graphene oxide (N-PGO) was synthesized, characterized, and applied as a hydrophilic nanomaterial in fabrication of polyethersulfone (PES) membrane for Reactive Red 195 dye and bovine serum albumin (BSA) protein separation. The N-PGO nanosheets not merely showed a good adhesion towards polymers, but simultaneously promoted hydrogen bonding action. Therefore, high-efficiency permeation passageway in the separation layer of membranes was attained. X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDX) and Fourier transform infra-red spectroscopy (FTIR) analyses approved nitrogen doping, which increased hydrophilicity and hydrogen bonding ability of PGO in water filtration. The pure water permeation of nanocomposite membranes could reach as high as 190 L m-2 h-1 at 3 bar. A dye rejection efficiency higher than 92% and BSA rejection higher than 95% were accordingly obtained. Atomic force microscopy (AFM) images approved formation of a rough surface that was decreased by addition of low amounts of the PGO. SEM images provided from the surface also confirmed enlarged pore size and increased porosity. Antifouling properties were investigated by BSA filtration, and results showed that the flux recovery ratio of the N-PGO membrane was improved. Overall, the N-PGO hybrid membranes exhibited potential for application in separation of typical proteins and dyes with good antifouling properties.

Interlaboratory Comparison of Hydrogen-Deuterium Exchange Mass Spectrometry Measurements of the Fab Fragment of NISTmAb.

Hydrogen-deuterium exchange mass spectrometry (HDX-MS) is an established, powerful tool for investigating protein-ligand interactions, protein folding, and protein dynamics. However, HDX-MS is still an emergent tool for quality control of biopharmaceuticals and for establishing dynamic similarity between a biosimilar and an innovator therapeutic. Because industry will conduct quality control and similarity measurements over a product lifetime and in multiple locations, an understanding of HDX-MS reproducibility is critical. To determine the reproducibility of continuous-labeling, bottom-up HDX-MS measurements, the present interlaboratory comparison project evaluated deuterium uptake data from the Fab fragment of NISTmAb reference material (PDB: 5K8A ) from 15 laboratories. Laboratories reported ∼89 800 centroid measurements for 430 proteolytic peptide sequences of the Fab fragment (∼78 900 centroids), giving ∼100% coverage, and ∼10 900 centroid measurements for 77 peptide sequences of the Fc fragment. Nearly half of peptide sequences are unique to the reporting laboratory, and only two sequences are reported by all laboratories. The majority of the laboratories (87%) exhibited centroid mass laboratory repeatability precisions of ⟨ sLab⟩ ≤ (0.15 ± 0.01) Da (1σx̅). All laboratories achieved ⟨sLab⟩ ≤ 0.4 Da. For immersions of protein at THDX = (3.6 to 25) °C and for D2O exchange times of tHDX = (30 s to 4 h) the reproducibility of back-exchange corrected, deuterium uptake measurements for the 15 laboratories is σreproducibility15 Laboratories( tHDX) = (9.0 ± 0.9) % (1σ). A nine laboratory cohort that immersed samples at THDX = 25 °C exhibited reproducibility of σreproducibility25C cohort( tHDX) = (6.5 ± 0.6) % for back-exchange corrected, deuterium uptake measurements.

Quantifying Protection in Disordered Proteins Using Millisecond Hydrogen Exchange-Mass Spectrometry and Peptic Reference Peptides.

The extent and location of transient structure in intrinsically disordered proteins (IDPs) provide valuable insights into their conformational ensembles and can lead to a better understanding of coupled binding and folding. Millisecond amide hydrogen exchange (HX) can provide such information, but it is difficult to quantify the degree of transient structuring. One reason is that transiently disordered proteins undergo HX at rates only slightly slower than the rate of amide HX by an unstructured random coil, the chemical HX rate. In this work, we evaluate several different methods of obtaining an accurate model for the chemical HX rate suitable for millisecond hydrogen exchange mass spectrometry (HX-MS) analysis of disordered proteins: (1) calculations using the method of Englander [Bai, Y., et al. (1993) Proteins 17, 75-86], (2) measurement of HX in the presence of 6 M urea or 3 M guanidinium chloride, and (3) measurement of HX by peptide fragments derived directly from the proteins of interest. First, using unstructured model peptides and disordered domains of the activator for thyroid and retinoid receptors and the CREB binding protein as the model IDPs, we show that the Englander method has slight inaccuracies that lead to underestimation of the chemical exchange rate. Second, HX-MS measurements of model peptides show that HX rates are changed dramatically by high concentrations of the denaturant. Third, we find that measurements of HX by reference peptides from the proteins of interest provide the most accurate approach for quantifying the extent of transient structure in disordered proteins by millisecond HX-MS.