Protein Moiety Research Articles

Erythroid spectrin binding modulates peroxidase and catalase activity of heme proteins.

Hemoglobin oxidation due to oxidative stress and disease conditions leads to the generation of ROS (reactive oxygen species) and membrane attachment of hemoglobin in-vivo, where its redox activity leads to peroxidative damage of membrane lipids and proteins. Spectrin, the major component of the red blood cell (RBC) membrane skeleton, is known to interact with hemoglobin and, here this interaction is shown to increase hemoglobin peroxidase activity in the presence of reducing substrate ABTS (2', 2'-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid). It is also shown that in the absence of reducing substrate, spectrin forms covalently cross-linked aggregates with hemoglobin which display no peroxidase activity. This may have implications in the clearance of ROS and limiting peroxidative damage. Spectrin is found to modulate the peroxidase activity of different hemoglobin variants like A, E, and S, and of isolated globin chains from each of these variants. This may be of importance in disease states like sickle cell disease and HbE-β-thalassemia, where increased oxidative damage and free globin subunits are present due to the defects inherent in the hemoglobin variants associated with these diseases. This hypothesis is corroborated by lipid peroxidation experiments. The modulatory role of spectrin is shown to extend to other heme proteins, namely catalase and cytochrome-c. Experiments with free heme and Raman spectroscopy of heme proteins in the presence of spectrin show that structural alterations occur in the heme moiety of the heme proteins on spectrin binding, which may be the structural basis of increased enzyme activity.

Biocatalytic lipoprotein bioamphiphile induced treatment of recalcitrant hydrocarbons in petroleum refinery oil sludge through transposon technology

The present investigation employed transposon technology to enhance the degradation of recalcitrant petroleum hydrocarbons present in petroleum oil sludge by using biosurfactant hyper-producing strain Enterobacter xiangfangensis STP-3. Out of 2500 transposon induced mutants, mutants M257E.xiangfangensis and M916E.xiangfangensis hyper-produce biocatalytic lipoprotein biosurfactant by1.98 and 2.34 fold higher than wild-type strain. Transposon induced mutation also modified the amino acid composition which improved the hydrophobicity and thermal stability of the biosurfactants produced by mutants, compared to the wild-type biosurfactant. GC-MS and LC-MS-MS revealed that biosurfactants have pentameric lipid moiety and esterase as protein moiety. Increased biosurfactant hydrophobicity and yield by the mutants resulted in the enhanced bioavailability of petroleum hydrocarbons, thereby mutants M257E.xiangfangensis and M916E.xiangfangensis demonstrated better petroleum oil sludge degradation by 82% and 88% respectively, than wild-type (72%). Disrupted genes vgr G and pgm M in M257E.xiangfangensis and M916E.xiangfangensis respectively hyper-produce biosurfactant by competitive pathway inhibition and increased precursor availability mechanism. Hyper-production of biosurfactant was also validated by comparing the expression of biosynthetic genes ent E, ent F and est using qPCR. This is the first report on the application of transposon technology to hyper-produce biosurfactant for the effective bioremediation of hydrocarbon contaminated environments.

Rethinking Opsins.

Opsins, the protein moieties of animal visual photo-pigments, have emerged as moonlighting proteins with diverse, light-dependent and -independent physiological functions. This raises the need to revise some basic assumptions concerning opsin expression, structure, classification, and evolution.

Polysaccharide-Protein Complex Isolated from Fruiting Bodies and Cultured Mycelia of Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes), Attenuates Doxorubicin-Induced Oxidative Stress and Myocardial Injury in Rats.

This study aimed to evaluate the effect of the polysaccharide-protein complex isolated from the fruiting bodies (GLFPPC) and cultured mycelia (GLMPPC) of a highly valued medicinal mushroom, Ganoderma lucidum, to alleviate doxorubicin (DOX)-induced cardiotoxicity. GLFPPC and GLMPPC were isolated from aqueous-alcoholic extracts of fruiting bodies and cultured mycelia of G. lucidum by repeated ethanol precipitation, dialysis, treatment with Sevag reagent, and freeze drying. The polysaccharide component was confirmed by assays with anthrone and phenol-sulphuric acid regents and protein moiety with Bradford reagent. The amino acid profile of protein moiety was determined by high-performance liquid chromatography analysis. DOX-induced cardiotoxicity was determined using Swiss albino mice. DOX administration caused a marked increase of creatine kinase and lactate dehydrogenase enzyme activities, indicating injury to the myocardium. The polysaccharide-protein complex downregulated cardiac injury marker enzymes, enhanced activities of endogenous antioxidants (namely, superoxide dismutase, catalase, glutathione peroxidase, and reduced glutathione levels), and significantly attenuated lipid peroxidation. The results indicated that GLFPPC and GLMPPC imparted protection against DOX-induced oxidative stress. Biochemical assays coupled with histopathological observations supported this conclusion. These experimental findings suggest that the polysaccharide-protein complex isolated from G. lucidum might be a useful therapeutic agent to ameliorate DOX-induced cardiomyopathy.

Phosphatase inhibition by sodium orthovanadate displays anti-inflammatory action by suppressing AKT-IKKβ signaling in RAW264.7 cells

Sodium orthovanadate (Na3VO4) is an inhibitor of phosphatases that acts as a phosphate analog and is being developed as an anti-diabetes drug. Phosphatases play important roles in inflammatory signal pathways by modulating the removal of phosphate moieties of key signaling proteins. However, the role of protein phosphatases on the inflammatory response has not been fully established. In this study, we investigated how phosphatases can control the inflammatory response using Na3VO4 in LPS-stimulated RAW264.7 cells and explored the molecular mechanisms by NO assay, mRNA analysis, immunoblotting analysis, kinase assay, luciferase reporter gene assay, and mutation strategy. Na3VO4 decreased the release of nitric oxide (NO) and suppressed the expression of pro-inflammatory genes at the transcriptional level, without cytotoxicity. The translocation of nuclear factor (NF)-κB subunits into the nucleus and the level of p-IκBα were reduced by Na3VO4, as was IKKβ activity. Na3VO4 inhibited NF-κB-Luc activity under AKT1/2 and IKKβ overexpression. However, the inhibitory effect of Na3VO4 against NF-κB-Luc was not observed in the group overexpressing both AKT2 and IKKβ-M10, a mutant in which the 10 serine residues in the autophosphorylated region of the C-terminal were replaced with alanine. Na3VO4 directly decreased the activity of protein phosphatase 1α (PP1α) and protein phosphatase 2 A (PP2A) by 95%. Phosphatase inhibition by Na3VO4 also selectively suppressed AKT-IKKβ signaling by directly blocking the phosphatase activity of PP1 and PP2A, consequently down-regulating NF-κB and inflammatory gene expression. Therefore, these results suggest that vanadium compounds including Na3VO4 can be developed as anti-inflammatory drugs.

Novel insights into chlorine dioxide based disinfection mechanisms – investigation of the reaction with amino acids

This study systematically investigated the reactions of N-acetyl-l-tyrosine (NAL-tyrosine) and N-acetyl-l-tryptophan (NAL-tryptophan) as examples for reactive moieties of microbial membrane proteins with ClO2 and FAC.

The RNase P, LUCA, the ancestors of the life domains, the progenote, and the tree of life

I have tried to interpret the phylogenetic distribution of the RNase P with the aim of helping to clarify the stage reached by the evolution of cellularity in the Last Universal Common Ancestor (LUCA); that is to say, if the evolutionary stage of the LUCA was represented by a protocell (progenote) or by a complete cell (genote). Since there are several arguments that lead one to believe that only the RNA moiety of the RNase P was present in the LUCA, this might imply that this evolutionary stage was actually the RNA world. If true this would imply that the LUCA was a progenote because the RNA world being a world subject to multiple evolutionary transitions that would involve a high noise at many its levels, which would fall within the definition of the progenote. Furthermore, since RNA-mediated catalysis is much less efficient than protein-mediated catalysis, then the only RNA moiety that was present in the LUCA could imply - by per se, without invoking the existence of the RNA world - that the LUCA was a progenote because an inefficient catalysis might have characterized this evolutionary stage. This evolutionary stage would still fall under the definition of the progenote. In addition, the observation that the protein moieties of the RNase P of bacteria and archaea are not-homologs would imply that these originated independently in the two main phyletic lineages. In turn, this would imply the progenotic nature of the ancestors of both archaea and bacteria. Indeed, it is admissible that such a late origin - in the main phyletic lineages - of the protein moieties of the RNase P is witness to an evolutionary transition towards a more efficient catalysis, evidently made clear precisely by the evolution of the protein moieties of the RNase P which would have helped the RNA of the RNase P to a more efficient catalysis. Hence, this would date that evolutionary moment as a transition to a much more efficient catalysis and consequently would imply which in that evolutionary stage there was the actual transition from the progenotic to genotic status. Finally, this late origin of the RNase P protein moieties in the bacterial and archaeal domains per se could imply the presence of a progenotic stage for their ancestors, or at least that a cell stage would have been much less likely. In fact, it is true that genes can originate both in a cellular and in a progenotic stage, but they mainly typify the latter because they are, by definition, in formation. Then it is expected that in the evolutionary stage of the formation of the main phyletic lineages - that is to say, in an evolutionary time in which the formation of genes might be expected - that the origin of proteins is to be related to a rapid and progressive evolution typical of the progenote precisely because in such an evolutionary stage the origin of genes is more easily and simply explained as reflecting a progenotic rather than a genotic stage. Indeed, if instead the evolutionary stage of the ancestors of bacteria and archaea had been the cellular one, then observing the origin of the protein moieties of the RNase P would have been, to some extent, anomalous because this completion should have already occurred, simply because the transformation of a ribozyme into an enzyme should have already taken place precisely because it falls within the very definition of the cellular status. The conclusion is that both the LUCA and the ancestor of archaea and that of bacteria may have been progenotes. If these arguments were true then either the tree of life as commonly understood would not exist and therefore the main phyletic lineages would have originated directly from the LUCA, or there would have been at least two different populations of progenotes that would have finally defined the domain of bacteria and that of archaea.

Dynamics of Apolipoprotein B-100 in Interaction with Detergent Probed by Incoherent Neutron Scattering.

Apolipoprotein B-100 (apo B-100) is the protein moiety of both low- and very-low-density lipoproteins, whose role is crucial to cholesterol and triglyceride transport. Aiming at the molecular dynamics' details of apo B-100, scarcely studied, we performed elastic and quasi-elastic incoherent neutron scattering (EINS, QENS) experiments combining different instruments and time scales. Similar to classical membrane proteins, the solubilization results in remaining detergent, here Nonidet P-40 (NP40). Therefore, we propose a framework for QENS studies of protein-detergent complexes, with the introduction of a combined model, including the experimental apo B-100/NP40 ratio. Relying on the simultaneous analysis of all QENS amplitudes, this approach is sensitive enough to separate both contributions. Its application identified two points: (i) apo B-100 slow dynamics and (ii) the acceleration of NP40 dynamics in the presence of apo B-100. Direct translation of the exposed methodology now makes the investigation of more membrane proteins by neutron spectroscopy achievable.

The Impact of Mutations on the Pathogenic and Antigenic Activity of SARS-CoV-2 during the First Wave of the COVID-19 Pandemic: A Comprehensive Immunoinformatics Analysis.

An in-depth analysis of first-wave SARS-CoV-2 genome is required to identify various mutations that significantly affect viral fitness. In the present study, we performed a comprehensive in silico mutational analysis of 3C-like protease (3CLpro), RNA-dependent RNA polymerase (RdRp), and spike (S) proteins with the aim of gaining important insights into first-wave virus mutations and their functional and structural impact on SARS-CoV-2 proteins. Our integrated analysis gathered 6000 SARS-CoV-2 sequences and identified 92 mutations in S, 37 in RdRp, and 11 in 3CLpro regions. The impact of these mutations was also investigated using various in silico approaches. Among these, 32 mutations in S, 15 in RdRp, and 3 in 3CLpro proteins were found to be deleterious in nature and could alter the structural and functional behavior of the encoded proteins. The D614G mutation in spike and the P323Lmutation in RdRp are the globally dominant variants with a high frequency. Most of the identified mutations were also found in the binding moiety of the viral proteins which determine their critical involvement in host–pathogen interactions and may represent drug targets. Furthermore, potential CD4+ and CD8+ T cell epitopes were predicted, and their overlap with genetic variations was explored. This study also highlights several hot spots in which HLA and drug selective pressure overlap. The findings of the current study may allow a better understanding of COVID-19 diagnostics, vaccines, and therapeutics.

Adsorption of arabinogalactan-proteins from Acacia gums (senegal and seyal) and its molecular fractions onto latex particles

Adsorption of Acacia gums (GA) (A. senegal and A. seyal) and A. senegal molecular fractions, made of arabinogalactan-proteins (AGPs) with different molecular weights, onto latex particles, with different sizes and surface charges, was studied using molecular (fluorescence and nanoIR spectroscopies, microscopies including Atomic Force Microscopy) and mesoscopic (Dynamic Light Scattering, zeta potential, Asymmetrical flow field-flow fractionation) methods. Adsorption of GA onto latex particles revealed a complex mechanism of adsorption where the highest adsorption was observed when A. senegal and latex particles were negatively charged. The invert was observed for A. seyal where the maximum of adsorption was observed when gum and latex were oppositely charged. The duality of positive and negative charges on GA macromolecules together with conformational changes certainly explain the complex mechanism of adsorption. A mechanism where either the protein moiety either the sugars blocks adsorb is to be preferred. This mechanism seems to produce differences of behaviour due to viscoelastic properties of adsorbed layers, and differences of hydration due to differences of polarity of AGPs. The consequence of electrostatics in the adsorption process is a water release from the adsorbed layers and important gain in entropy. A fair agreement was found between protein content and adsorbed layer thickness of GA, with the formation of partial coverage, monolayer and multilayer films depending on GA concentration. Structural changes induced by GA adsorption onto latex particles was probed using fluorescence and nanoIR spectroscopies without giving clear evidence of conformational changes induced after GA adsorption. The results of this study highlighted that GA surface adsorption process depend not only on the protein moiety and electrostatic interactions but also on other parameters related to AGP hydration status. The protein structural accessibility, the molecular weight distribution, the AGPs intrinsic viscoelastic properties allowing structural rearrangements on the surface and spreading in order to form a viscoelastic film onto latex particles should also play a pivotal role in the adsorption process.

Assessing HDL Metabolism in Subjects with Elevated Levels of HDL Cholesterol and Coronary Artery Disease.

High-density lipoprotein cholesterol (HDL-C) is thought to be atheroprotective yet some patients with elevated HDL-C levels develop cardiovascular disease, possibly due to the presence of dysfunctional HDL. We aimed to assess the metabolic fate of circulating HDL particles in patients with high HDL-C with and without coronary artery disease (CAD) using in vivo dual labeling of its cholesterol and protein moieties. We measured HDL apolipoprotein (apo) A-I, apoA-II, free cholesterol (FC), and cholesteryl ester (CE) kinetics using stable isotope-labeled tracers (D3-leucine and 13C2-acetate) as well as ex vivo cholesterol efflux to HDL in subjects with (n = 6) and without (n = 6) CAD that had HDL-C levels >90th percentile. Healthy controls with HDL-C within the normal range (n = 6) who underwent the same procedures were used as the reference. Subjects with high HDL-C with and without CAD had similar plasma lipid levels and similar apoA-I, apoA-II, HDL FC, and CE pool sizes with no significant differences in fractional clearance rates (FCRs) or production rates (PRs) of these components between groups. Subjects with high HDL-C with and without CAD also had similar basal and cAMP-stimulated ex vivo cholesterol efflux to HDL. When all subjects were considered (n = 18), unstimulated non-ABCA1-mediated efflux (but not ABCA1-specific efflux) was correlated positively with apoA-I production (r = 0.552, p = 0.017) and HDL FC and CE pool sizes, and negatively with the fractional clearance rate of FC (r = −0.759, p = 4.1 × 10−4) and CE (r = −0.652, p = 4.57 × 10−3). Our data are consistent with the concept that ex vivo non-ABCA1 efflux capacity may correlate with slower in vivo turnover of HDL cholesterol moieties. The use of a dual labeling protocol provided for the first time the opportunity to assess the association of ex vivo cholesterol efflux capacity with in vivo HDL cholesterol metabolic parameters.

Desmosome dualism - most of the junction is stable, but a plakophilin moiety is persistently dynamic.

Desmosomes, strong cell-cell junctions of epithelia and cardiac muscle, link intermediate filaments to cell membranes and mechanically integrate cells across tissues, dissipating mechanical stress. They comprise five major protein classes - desmocollins and desmogleins (the desmosomal cadherins), plakoglobin, plakophilins and desmoplakin - whose individual contribution to the structure and turnover of desmosomes is poorly understood. Using live-cell imaging together with fluorescence recovery after photobleaching (FRAP) and fluorescence loss and localisation after photobleaching (FLAP), we show that desmosomes consist of two contrasting protein moieties or modules: a very stable moiety of desmosomal cadherins, desmoplakin and plakoglobin, and a highly mobile plakophilin (Pkp2a). As desmosomes mature from Ca2+ dependence to Ca2+-independent hyper-adhesion, their stability increases, but Pkp2a remains highly mobile. We show that desmosome downregulation during growth-factor-induced cell scattering proceeds by internalisation of whole desmosomes, which still retain a stable moiety and highly mobile Pkp2a. This molecular mobility of Pkp2a suggests a transient and probably regulatory role for Pkp2a in desmosomes. This article has an associated First Person interview with the first author of the paper.

SUMO orchestrates multiple alternative DNA-protein crosslink repair pathways.

Endogenous metabolites, environmental agents, and therapeutic drugs promote formation of covalent DNA-protein crosslinks (DPCs). Persistent DPCs compromise genome integrity and are eliminated by multiple repair pathways. Aberrant Top1-DNA crosslinks, or Top1ccs, are processed by Tdp1 and Wss1 functioning in parallel pathways in Saccharomyces cerevisiae. It remains obscure how cells choose between diverse mechanisms of DPC repair. Here, we show that several SUMO biogenesis factors (Ulp1, Siz2, Slx5, and Slx8) control repair of Top1cc or an analogous DPC lesion. Genetic analysis reveals that SUMO promotes Top1cc processing in the absence of Tdp1 but has an inhibitory role if cells additionally lack Wss1. In the tdp1Δ wss1Δ mutant, the E3 SUMO ligase Siz2 stimulates sumoylation in the vicinity of the DPC, but not SUMO conjugation to Top1. This Siz2-dependent sumoylation inhibits alternative DPC repair mechanisms, including Ddi1. Our findings suggest that SUMO tunes available repair pathways to facilitate faithful DPC repair.

The thermodynamic and kinetic mechanisms of a Ganoderma lucidum proteoglycan inhibiting hIAPP amyloidosis

Ganoderma lucidum is a valuable medicinal herbal which has been reported to prevent type 2 diabetes (T2D). A natural hyperbranched proteoglycan extracted from Ganoderma lucidum, namely, FYGL, has been demonstrated to inhibit the amyloidosis of human islet amyloid polypeptide (hIAPP) previously by our lab. However, the effective active components and the mechanisms of FYGL in inhibiting hIAPP amyloidosis are unknown. To identify the effective active components, different components from FYGL were isolated: the polysaccharide FYGL-1, the proteoglycans of FYGL-2 and FYGL-3. We further separated and sequenced the protein moieties of FYGL-2 and FYGL-3, namely, FYGL-2-P and FYGL-3-P, respectively, and compared their abilities to inhibit hIAPP amyloidosis, and systematically explored the inhibitory mechanisms by spectroscopy, microscopy and molecular dynamic simulation methods. Results showed that the protein moieties of FYGL played essential roles in inhibiting hIAPP amyloidosis. The strong, specific, and enthalpy-driven interaction by π-π stacking and electrostatic forces between hIAPP and FYGL-3-P dramatically inhibited hIAPP amyloidosis. These results suggested that FYGL-3-P had enormous potential to prevent hIAPP misfolding-induced diabetes and structurally helped researchers to seek or design inhibitors against polypeptide amyloidosis.

Interaction and Inhibition of a Ganoderma lucidum Proteoglycan on PTP1B Activity for Anti-diabetes.

Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of insulin and an effective target for the treatment of type 2 diabetes (T2D). A natural hyperbranched proteoglycan extracted from Ganoderma lucidum, namely, Fudan-Yueyang G. Lucidum (FYGL), was demonstrated capable of inhibiting the activity of PTP1B. Here, to identify the effective active components of FYGL, three different components, the polysaccharide FYGL-1, proteoglycans FYGL-2, and FYGL-3, were isolated from FYGL, and then, the protein moiety of FYGL-3 was further separated, namely, FYGL-3-P. Their abilities to enhance the glucose uptake in cells and inhibit the activity of PTP1B were compared. The inhibitory mechanisms were systematically explored by spectroscopic methods and MD simulations. The results showed that FYGL-3 and FYGL-3-P significantly enhanced the insulin-provoked glucose uptake in insulin-resistant HepG2 cells, detected by the glucose oxidase method. Also, the FYGL-3-P protein moiety in FYGL played an essential role in inhibiting the activity of PTP1B. A strong, enthalpy-driven, and multitargeted interaction by electrostatic forces between PTP1B and FYGL-3-P dramatically inhibited the catalytic activity of PTP1B. These results provided deep insights into the molecular mechanisms of FYGL inhibiting the activity of PTP1B and structurally helped researchers seek natural PTP1B inhibitors.

Structural characteristics of Saccharomyces cerevisiae mannoproteins: Impact of their polysaccharide part

While they have many properties of interest in enology, the structure-function relationships of mannoproteins and the part played by their polysaccharide moiety are not yet well understood. Mannoproteins (MP) extracted with β-glucanase from a laboratory yeast strain (WT), two of its mutants (Mnn2 with unbranched N-glycosylated chains and Mnn4 without mannosyl-phosphorylation), and an enological strain (Com) were purified and thoroughly characterized. The protein moiety of the four MPs had the same amino acid composition. Glycosyl-linkage and net charge analyses confirmed the expected differences in mutant strain MPs. MP-Com had the highest mannose/glucose ratio followed by MP-WT/MP-Mnn4, and MP-Mnn2 (13.5 > 5.6 ≈ 5.2 > 2.2). The molar mass dependencies of Rg, Rh, and [η], determined through HPSEC-MALLS-QELS-Viscosimetry, revealed specific conformational properties of mannoproteins related to their nature of highly branched copolymers with two branching levels. It also clearly showed structural differences between MP-Com, MP-WT/Mnn4, and MP Mnn2, and differences between two populations within the four mannoproteins.

Urinary excretion of amino acids and their advanced glycation end-products (AGEs) in adult kidney transplant recipients with emphasis on lysine: furosine excretion is associated with cardiovascular and all-cause mortality

Arginine (Arg) and lysine (Lys) moieties of proteins undergo various post-translational modifications (PTM) including enzymatic NG- and Nε-methylation and non-enzymatic NG- and Nε-glycation. In a large cohort of stable kidney transplant recipients (KTR, n = 686), high plasma and low urinary concentrations of asymmetric dimethylarginine (ADMA), an abundant PTM metabolite of Arg, were associated with cardiovascular and all-cause mortality. Thus, the prediction of the same biomarker regarding mortality may depend on the biological sample. In another large cohort of stable KTR (n = 555), higher plasma concentrations of Nε-carboxymethyl-lysine (CML) and Nε-carboxyethyl-lysine (CEL), two advanced glycation end-products (AGEs) of Lys, were associated with higher cardiovascular mortality. Yet, the associations of urinary AGEs with mortality are unknown. In the present study, we measured 24 h urinary excretion of Lys, CML, and furosine in 630 KTR and 41 healthy kidney donors before and after donation. Our result indicate that lower urinary CML and lower furosine excretion rates are associated with higher mortality in KTR, thus resembling the associations of ADMA. Lower furosine excretion rates were also associated with higher cardiovascular mortality. The 24 h urinary excretion rate of amino acids and their metabolites decreased post-donation (varying as little as − 24% for CEL, and as much as − 62% for ADMA). For most amino acids, the excretion rate was lower in KTR than in donors pre-donation [except for S-(1-carboxyethyl)-l-cysteine (CEC) and NG-carboxyethylarginine (CEA)]. Simultaneous GC–MS measurement of free amino acids, their PTM metabolites and AGEs in urine is a non-invasive approach in kidney transplantation.

Concerted Motions and Molecular Function: What Physical Chemistry We Can Learn from Light-Driven Ion-Pumping Rhodopsins.

Transmembrane ion gradients are generated and maintained by ion-pumping proteins in cells. Light-driven ion-pumping rhodopsins are retinal-containing proteins found in archaea, bacteria, and eukarya. Photoisomerization of the retinal chromophore induces structural changes in the protein, allowing the transport of ions in a particular direction. Understanding unidirectional ion transport by ion-pumping rhodopsins is an exciting challenge for biophysical chemistry. Concerted changes in ion-binding affinities of the ion-binding sites in proteins are key to unidirectional ion transport, as is the coupling between the chromophore and the protein moiety to drive the concerted motions regulating ion-binding affinities. The commonality of ion-pumping rhodopsin protein structures and the diversity of their ion-pumping functions suggest universal principles governing ion transport, which would be widely applicable to molecular systems. In this Perspective, I review the insights obtained from previous studies on rhodopsins and discuss future perspectives.

Biophysical and Biochemical Research of Animal Rhodopsins

Opsins (also called animal rhodopsins) are universal photoreceptive proteins that provide the molecular basis of visual and nonvisual photoreception in animals, including humans. Opsins consist of seven helical α-transmembrane domains and use retinal, a derivative of vitamin A, as a chromophore. In many opsins, light absorption triggers photo-isomerization from 11-cis retinal to all-trans retinal, resulting in activation via dynamic structural changes in the protein moiety. Activated opsins stimulate cognate trimeric G proteins to induce signal transduction cascades in cells. Recently, molecular and physiological analyses of diverse opsins have progressively advanced. This review introduces the molecular basis and physiological functions of opsins. Based on the functions of opsins, I will discuss the potential of opsins as target molecules to treat and prevent visual and nonvisual diseases such as sleep disorder and depression.

Assessment of the Anti-Cancer Efficiency of Silver Moringa oleifera Leaves Nano-extract against Colon Cancer Induced Chemically in Rats.

Background:Colorectal cancer (CRC) categorized as the most common type of gastrointestinal cancers affected both genders equally. Chemotherapeutic drugs became limited due to their deleterious side effects. Therefore, efficiency of M. oleifera leaves extract increased by incorporating silver nanoparticles (Ag-NPs) then studied against colon cancer induced by azoxymethane (AOM) in rats. Methods:Different hematological and biochemical measurements in addition to specific tumor and inflammatory markers were quantified. Histopathological examination for Colonic tissues was performed. Native proteins and isoenzyme patterns were electrophoretically detected in addition to assaying expression of Tumor Protein P53 (TP53) and Adenomatous Polyposis Coli (APC) genes in colonic tissues.Results: M. oleifera nano-extract restored levels of the hematological and biochemical measurements in addition to levels of tumor and inflammatory markers to normalcy in both of nano-extract simult- and post-treated groups. Also, it minimized severity of the histopathological alterations in the simult-treated group and prevented it completely in the post-treated group. The lowest similarity index (SI%) values were noticed with electrophoretic protein (SI=61.54%), lipid (SI=0.00%) and calcium (SI=75.00%) moieties of protein patterns, catalase (SI=85.71%), peroxidase (SI=85.71%), α-esterase (SI=50.00%) and β-esterase (SI=50.00%) isoenzymes in addition to altering the relative quantities of total protein and isoenzyme bands in colon of cancer induced group. Moreover, levels of TP53 and APC gene expression increased significantly (P≤0.05) in colon cancer induced group. The nano-extract prevented the qualitative and quantitative alterations in the different electrophoretic patterns in addition to restoring levels of the gene expressions to normalcy in both of simult- and post-treated groups. Conclusion: M. oleifera nano-extract exhibited ameliorative effect against the biochemical, physiological and molecular alterations induced by AOM in nano-extract simult- and post-treated groups.