An investigation into non-covalent functionalization of a single-walled carbon nanotube and a graphene sheet with protein G:A combined experimental and molecular dynamics study.

Investigation of non-covalent interaction of hydrophobic surfaces with the protein G (PrG) is necessary due to their frequent utilization in immunosensors and ELISA. It has been confirmed that surfaces, including carbonous-nanostructures (CNS) could orient proteins for a better activation. Herein, PrG interaction with single-walled carbon nanotube (SWCNT) and graphene (Gra) nanostructures was studied by employing experimental and MD simulation techniques. It is confirmed that the PrG could adequately interact with both SWCNT and Gra and therefore fine dispersion for them was achieved in the media. Results indicated that even though SWCNT was loaded with more content of PrG in comparison with the Gra, the adsorption of the PrG on Gra did not induce significant changes in the IgG tendency. Several orientations of the PrG were adopted in the presence of SWCNT or Gra; however, SWCNT could block the PrG-FcR. Moreover, it was confirmed that SWCNT reduced the α-helical structure content in the PrG. Reduction of α-helical structure of the PrG and improper orientation of the PrG-SWCNT could remarkably decrease the PrG tendency to the Fc of the IgG. Importantly, the Gra could appropriately orient the PrG by both exposing the PrG-FcR and also by blocking the fragment of the PrG that had tendency to interact with Fab in IgG.

Protein G selects two binding sites for carbon nanotube with dissimilar behavior; a molecular dynamics study.

BACKGROUND: Study of nanostructure-protein interaction for development of various types of nano-devices is very essential. Among carbon nanostructures, carbon nanotube (CNT) provides a suitable platform for functionalization by proteins. Previous studies have confirmed that the CNT induces changes in the protein structure. METHODS: Molecular dynamics (MD) simulation study was employed to illustrate the changes occurring in the protein G (PGB) in the presence of a CNT. In order to predict the PGB surface patches for the CNT, Autodock tools were utilized. RESULTS: Docking results indicate the presence of two different surface patches with diverse amino acids: the dominant polar residues in the first (PGB-CNT1) and the aromatic residues in the second (PGB-CNT2) surface patch. Displacement of amino acids in the PGB-CNT2 complex occurred during the simulation and it caused an increase in its stability at the end of simulation. The amino acids' displacements diminished the PGB α-helix structure by breakage of hydrogen bonds and generated more transient structures. Principal component analysis determined that the interaction of the CNT with the second surface patch of the PGB raised the extent and modes of the PGB motions. In contrast, insignificant structural changes induced in the PGB while the CNT bonded through the first surface patch. CONCLUSION: Even though neither of the PGB-CNT complexes could prevent structural changes in the PGB, development of the PGB-CNT1 complex induce slight structural changes in its fragment of crystallizable receptor (FCR). Dissimilar structural changes induced in the PGB-CNT complexes are possibly related to various characteristics of the PGB binding sites.

Microbiota potential for the treatment of sexual dysfunction.

Inability to have a satisfactory sexual intercourse is a serious problem affecting many people. Despite enormous efforts for developing effective treatments for pathologic conditions associated with sexual malfunction, still a lot of patients do not respond well to such treatments. Microbiota has been shown to affect obesity, diabetes, hypertension, stress/anxiety and sex hormonal disturbances. Nevertheless, no research has concentrated on the link between microbiota and human sexuality or sexual dysfunction. We propose another line of enquiry into sexual dysfunction by hypothesizing a relationship between microbiota and factors affecting human sexuality. Hence, it can be assumed that microbiota manipulation may improve sexual behavior and reduce sexual dysfunction. We also discuss the evidence to back up this hypothesis, and present some predictions.

DBT desulfurization by decorating Rhodococcus erythropolis IGTS8 using magnetic Fe3O4 nanoparticles in a bioreactor.

Today, crude oil is an important source of energy and environmental contamination due to the continued use of petroleum products is a matter or urgent concern. In this work, two technological platforms, namely, the use of a robust desulfurizing bacteria and the use of nanotechnology to decorate the surface of the bacteria with nanoparticles (NP), were combined to enhance biodesulfurization (BDS). BDS is an ecologically friendly method for desulfurizing petroleum products while avoiding damage to the hydrocarbons due to the high temperatures normally associated with physical desulfurization methods. First, a bacterium known to be a good organism for desulfurization (Rhodococcus erythropolis IGTS8) was employed in cell culture to remove a recalcitrant sulfur molecule from a common sulfur-containing compound found in crude petroleum products (dibenzothiophene). 2-Hydroxybiphenyl (2-HBP) produced as a consequence of the BDS of dibenzothiophene was determined using Gibbs' assay. The synthesized NP were characterized by field emission scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and vibrating sample magnetometer. The field emission scanning electron microscope and transmission electron microscopy images showed the size of the NP is 7-8 nm. The decorated cells had a long lag phase, but the growth continued until 148 h (at OD600 = 3.408) while the noncoated bacteria grow until 96 h before entering the stationary phase at OD600 = 2.547. Gibbs' assay results showed that production of 2-HBP by decorated cells was 0.210 mM at t = 148 h, while 2-HBP production by nondecorated cells was 0.182 mM at t = 96 h. Finally, the experiments were repeated in a fermenter.

Fibrillation of alpha-lactalbumin: effect of crocin and safranal, two natural small molecules from Crocus sativus.

Formation of toxic amyloid structures is believed to be associated with various late-onset neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. The fact that many proteins in addition to those that are associated with clinical conditions have the potential to form amyloid fibrils in vitro provides opportunities for studying the fundamentals of protein aggregation and amyloid formation in model systems. Accordingly, considerable interest and effort has been directed toward developing small molecules to inhibit the formation of fibrillar assemblies and their associated toxicities. In the present study, we investigated the inhibitory effect of crocin and safranal, two principal components of saffron, on fibrillation of apo-alpha-lactalbumin (a-alpha-LA), used as a model protein, under amyloidogenic conditions. In the absence of any ligand, formation of soluble oligomers became evident after 18 h of incubation, followed by subsequent appearance of mature fibrils. Upon incubation with crocin or safranal, while transition phase to monomeric beta structures was not significantly affected, formation of soluble oligomers and following fibrillar assemblies were inhibited. While both safranal and crocin had the ability to bind to hydrophobic patches provided in the intermediate structures, and thereby inhibit protein aggregation, crocin was found more effective, possibly due to its simultaneous hydrophobic and hydrophilic character. Cell viability assay indicated that crocin could diminish toxicity while safranal act in reverse order.