151 research outputs found

    Regulation Mechanisms for Phospholipase Enzymes

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    The effect of hydrophobicity on susceptibility of phosphatidylcholine derivatives to PLA2 attack was studied by synthesising two series of compounds, the saturated symmetrically distributed derivatives and compounds with one long acyl-chain in the first position and a selected short-chain in the second position. The first series were used to investigate the effect of substrate morphology over the range from free monomer substrates through micelle to bilayer forms, the second series were used to examine the region of the micelle/bilayer transition at higher resolution. The symmetric substrates showed the expected properties with susceptibility increasing with hydrophobicity in the free monomer series and a sharp transition seen at the CMC for the shorter chain substrates. No such change was seen for longer chain substrates with any of these enzymes and the concept of a hydrophobic anchor increasing the rate of attack on condensed rather than monomeric substrates was questioned. These compounds were used to study the action of enzyme activated by treatment with oleoyl-imidazolide. The biggest activation factors were seen for asymmetric bilayer-forming substrates in propanolic solution, but the physico-chemical form of the substrates under these conditions was not established. Fatty acyl activation was found to alter the response to calcium activation and suggested a two-calcium site model. Studies of calcium activation showed very strong evidence for two kinetically important sites. Metal ion inhibition showed that barium and large cations were competitive inhibitors for calcium, but zinc and cadmium were not and appeared to inhibit a component of activation only found at high calcium activation. This lead to the proposal that zinc and barium bind to the enzyme at different calcium binding sites. Hydrolysis curves were shown to vary in shape depending on calcium concentration and the anomalous shape was associated with the presence of calcium at a single binding site. Addition of zinc removed the anomalous shape and without giving further enzyme activation whilst addition of calcium changes the curve shape and was activating. Some evidence was presented to suggest that the presence of a metal ion in the second (zinc) site was important for modulating the activation of the enzyme with surfaces. The use of the conductimetric assay was extended to the purification and characterisation of PLD enzymes acting as both transferases and hydrolases The transferase activity was used to generate phosphatidyl alcohols from DiC8PC and the methanol derivative was shown to be better substrate than the PC equivalent but to posess chartacteristics of the monomeric form. Polar phosphatidic acid compounds which should have high CMC values sould enable the relationship between structure, morphology and susceptibility to PLA2 to be examined in detail

    Engineering a microbiosphere to clean up the ocean – inspiration from the plastisphere

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    Plastic is a ubiquitous material that has become an essential part of our lives. More than one hundred million tons of plastic has accumulated in the world’s oceans as a result of poor waste management. This plastic waste gradually fragments into smaller pieces known as microplastics and nanoplastics. These small plastic particles can cause significant damage to marine ecosystems, and negatively impact human health. According to a recent review of international patents, the majority of ocean-cleaning inventions are limited to microplastics larger than 20 ÎŒm. Furthermore, such technologies are ineffective for nanoplastics, which measure less than 1000 nm, or even fibrous plastics. Alternative solutions need to be considered for the large-scale in situ removal of microplastics and nanoplastics from the ocean. In this perspective, we present the concept of engineering a microbial ecosystem, which we term the microbiosphere. The concept is based on key observations that have been made for natural plastic-based ecosystems known as plastispheres. These observations relate to the solid support material, self-sustainability, attachment to plastic, degradation of plastic, and risk of pathogenicity. Inspiration can be taken from the plastisphere whereby a novel microbial ecosystem could be designed and engineered as a bioremediation tool to rid the ocean of micro- and nanoplastics. Such an engineered system could outcompete pathogens for marine plastic waste and potentially reduce the risk of infectious diseases

    A fully automated procedure for the parallel, multidimensional purification and nucleotide loading of the human GTPases KRas, Rac1 and RalB

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    Small GTPases regulate many key cellular processes and their role in human disease validates many proteins in this class as desirable targets for therapeutic intervention. Reliable recombinant production of GTPases, often in the active GTP loaded state, is a prerequisite for the prosecution of drug discovery efforts. The preparation of these active forms can be complex and often constricts the supply to the reagent intensive techniques used in structure base drug discovery. We have established a fully automated, multidimensional protein purification strategy for the parallel production of the catalytic G-domains of KRas, Rac1 and RalB GTPases in the active form. This method incorporates a four step chromatography purification with TEV protease-mediated affinity tag cleavage and a conditioning step that achieves the activation of the GTPase by exchanging GDP for the non-hydrolyzable GTP analogue GMPPnP. We also demonstrate that an automated method is efficient at loading of KRas with mantGDP for application in a SOS1 catalysed fluorescent nucleotide exchange assay. In comparison to more conventional manual workflows the automated method offers marked advantages in method run time and operator workload. This reduces the bottleneck in protein production while generating products that are highly purified and effectively loaded with nucleotide analogues

    Descriptive Analysis of Physical Activity Initiatives for Health Promotion in Saudi Arabia

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    Background: Although the benefits of physical activity are well acknowledged, a high percentage of Saudi population, especially females, remain essentially physically inactive. Getting inactive people to start participating in physical activity and to keep exercising remains a great challenge. Physical activity initiatives in the country have not been previously documented. Therefore, the aim of this article was to provide a narrative review of the physical activity initiatives and discusses influencing factors.Methods: Publically-available physical activity initiatives conducted before June 2018 were searched through the web or they were obtained straight from the organization themselves. The search focus was on any initiative aimed to promote physical activity and mass sports participation and encourage people to adopt active living habit.Results: Numerous initiatives aimed at promoting physical activity existed in Saudi Arabia. However, a common attribute of these initiatives is that they were fragmented, short term attempts, and lacked a coordinating body. The majority of the physical activity initiatives also lacked objective evaluations of their outcomes. It was clear that more physical activity opportunity must be provided for Saudi girls, women, and elderly. There is a need for establishing a national policy encouraging active living and discouraging sedentary lifestyle with contributions from all involved parties.Conclusions: Based on the available evidences, more intensified efforts toward promoting physical activity and reducing sedentary behaviors among Saudi population are needed in order to reduce the risks of NCD's

    Synthesis, X-ray, Hirshfeld, and AIM Studies on Zn(II) and Cd(II) Complexes with Pyridine Ligands

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    The synthesis and crystal structures of three heteroleptic complexes of Zn(II) and Cd(II) with pyridine ligands (ethyl nicotinate (EtNic), N,N-diethylnicotinamide (DiEtNA), and 2-amino-5-picoline (2Ampic) are presented. The complex [Zn(EtNic)2Cl2] (1) showed a distorted tetrahedral coordination geometry with two EtNic ligand units and two chloride ions as monodentate ligands. Complexes [Zn(DiEtNA)(H2O)4(SO4)]·H2O (2) and [Cd(OAc)2(2Ampic)2] (3) had hexa-coordinated Zn(II) and Cd(II) centers. In the former, the Zn(II) was coordinated with three different monodentate ligands, which were DiEtNA, H2O, and SO42−. In 3, the Cd(II) ion was coordinated with two bidentate acetate ions and two monodentate 2Ampic ligand units. The supramolecular structures of the three complexes were elucidated using Hirshfeld analysis. In 1, the most important interactions that governed the molecular packing were O···H (15.5–15.6%), Cl···H (13.6–13.8%), Cl···C (6.3%), and C···H (10.3–10.6%) contacts. For complexes 2 and 3, the H···H, O···H, and C···H contacts dominated. Their percentages were 50.2%, 41.2%, and 7.1%, respectively, for 2 and 57.1%, 19.6%, and 15.2%, respectively, for 3. Only in complex 3, weak π-π stacking interactions between the stacked pyridines were found. The Zn(II) natural charges were calculated using the DFT method to be 0.8775, 1.0559, and 1.2193 for complexes 1–3, respectively. A predominant closed-shell character for the Zn–Cl, Zn–N, Zn–O, Cd–O, and Cd–N bonds was also concluded from an atoms in molecules (AIM) study

    5-deazaflavin derivatives as inhibitors of p53 ubiquitination by HDM2

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    Based on previous reports of certain 5-deazaflavin derivatives being capable of activating the tumour suppressor p53 in cancer cells through inhibition of the p53-specific ubiquitin E3 ligase HDM2, we have conducted an structure–activity relationship (SAR) analysis through systematic modification of the 5-deazaflavin template. This analysis shows that HDM2-inhibitory activity depends on a combination of factors. The most active compounds (e.g., 15) contain a trifluoromethyl or chloro substituent at the deazaflavin C9 position and this activity depends to a large extent on the presence of at least one additional halogen or methyl substituent of the phenyl group at N10. Our SAR results, in combination with the HDM2 RING domain receptor recognition model we present, form the basis for the design of drug-like and potent activators of p53 for potential cancer therapy

    Attenuating Muscle Damage Biomarkers and Muscle Soreness After an Exercise-Induced Muscle Damage with Branched-Chain Amino Acid (BCAA) Supplementation:A Systematic Review and Meta-analysis with Meta-regression

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    Background: Branched-chain amino acid (BCAA) supplementation is one of the most popular strategies used by the general population and athletes to reduce muscle soreness and accelerate the recovery process of muscle damage biomarkers after an intense exercise or training session. Objectives: This systematic review and meta-analysis investigated the effects of BCAA supplementation on muscle damage biomarkers and muscle soreness after exercise-induced muscle damage (EIMD). Methods: The systematic literature search for randomized controlled trials was conducted using seven databases, up to September 13th, 2022. The eligibility criteria for selecting studies were as follows: studies performed on healthy active participants, using BCAA at least once, controlled with a placebo or control group, performing resistance or endurance exercises, and followed up at least once post-EIMD. The methodological quality of the studies was assessed using the “SIGN RCT checklist”. Random-effects meta-analyses were processed to compute the standardized mean difference (Hedges’ g). Meta-regression analyses were completed with daily and total dosage and supplementation as continuous moderator variables. Results: Of the 18 studies included in this meta-analysis, 13 were of high quality and five were of acceptable quality. Our results revealed BCAA supplementation elicits a significant effect on reducing creatine kinase (CK) levels immediately (g = − 0.44; p = 0.006) and 72 h (g = − 0.99; p = 0.002), but not 24 h, 48 h, and 96 h post-EIMD. Additionally, a significant effect on delayed onset of muscle soreness (DOMS) was identified at 24 h (g = − 1.34; p < 0.001), 48 h (g = − 1.75; p < 0.001), 72 h (g = − 1.82; p < 0.001), and 96 h (g = − 0.82; p = 0.008), but not immediately post-EIMD. No significant effect was found on lactate dehydrogenase (LDH) levels at any time point. Meta-regression indicated higher daily and total dosages of BCAA, and longer supplementation periods were related to the largest beneficial effects on CK (total dosage and supplementation period) at 48 h, and on DOMS at 24 h (only daily dosage). Conclusion: The overall effects of BCAA supplementation could be considered useful for lowering CK and DOMS after EIMD, but not LDH. The longer supplementation period prior to the EIMD could be more effective for CK and DOMS reduction
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