The digestive enzymes-polyphenolic compounds (PCs) interactions behind the inhibition of these enzymes have not been completely studied. The existing studies have mainly analyzed polyphenolic ...extracts and reported inhibition percentages of catalytic activities determined by UV-Vis spectroscopy techniques. Recently, pure PCs and new methods such as isothermal titration calorimetry and circular dichroism have been applied to describe these interactions. The present review focuses on PCs structural characteristics behind the inhibition of digestive enzymes, and progress of the used methods. Some characteristics such as molecular weight, number and position of substitution, and glycosylation of flavonoids seem to be related to the inhibitory effect of PCs; also, this effect seems to be different for carbohydrate-hydrolyzing enzymes and proteases. The digestive enzyme-PCs molecular interactions have shown that non-covalent binding, mostly by van der Waals forces, hydrogen binding, hydrophobic binding, and other electrostatic forces regulate them. These interactions were mainly associated to non-competitive type inhibitions of the enzymatic activities. The present review emphasizes on the digestive enzymes such as α-glycosidase (AG), α-amylase (PA), lipase (PL), pepsin (PE), trypsin (TP), and chymotrypsin (CT). Existing studies conducted in vitro allow one to elucidate the characteristics of the structure-function relationships, where differences between the structures of PCs might be the reason for different in vivo effects.
The X-ray spectra of many active galactic nuclei (AGNs) show a soft X-ray excess below 1–2 keV on top of the extrapolated high-energy power law. The origin of this component is uncertain. It could be ...a signature of relativistically blurred, ionized reflection or the high-energy tail of thermal Comptonization in a warm (kT ~ 1 keV), optically thick (τ ≃ 10–20) corona producing the optical/UV to soft X-ray emission. The purpose of the present paper is to test the warm corona model on a statistically significant sample of unabsorbed, radio-quiet AGNs with XMM-Newton archival data, providing simultaneous optical/UV and X-ray coverage. The sample has 22 objects and 100 observations. We use two thermal Comptonization components to fit the broadband spectra, one for the warm corona emission and one for the high-energy continuum. In the optical/UV, we also include the reddening, the small blue bump, and the Galactic extinction. In the X-rays, we include a warm absorber and a neutral reflection. The model gives a good fit (reduced χ2 < 1.5) to more than 90% of the sample. We find the temperature of the warm corona to be uniformly distributed in the 0.1–1 keV range, while the optical depth is in the range ~10–40. These values are consistent with a warm corona covering a large fraction of a quasi-passive accretion disk, i.e., that mostly reprocesses the warm corona emission. The disk intrinsic emission represents no more than 20% of the disk total emission. According to this interpretation, most of the accretion power would be released in the upper layers of the accretion flow.
Excess fatty acids are stored in cells as triglycerides in specialized organelles called lipid droplets (LD). LD can be found in nearly all cell types and may expand during certain ...(patho)physiological conditions. The synthesis and breakdown of triglycerides and their deposition in LD is governed by a diverse set of enzymes and LD-associated proteins. These proteins serve structural roles in and around LD and regulate the activity of key lipogenic and lipolytic enzymes. The LD-associated proteins are subject to multiple regulatory mechanisms at the protein and gene expression level. A group of transcription factors that govern the expression of many LD-associated proteins are the Peroxisome Proliferator-Activated Receptors (PPARs). PPARs are lipid-activated transcription factors that play a key role in the regulation of lipid metabolism in liver (PPARα), adipose tissue (PPARγ), and skeletal muscle (PPARδ). This review provides an overview of the regulation of LD-associated proteins by PPARα, PPARδ, and PPARγ in adipose tissue, liver, macrophages, and skeletal muscle. It is concluded that many LD-associated proteins, including members of the PLIN family, CIDEC, CIDEA, HILPDA, FITM1, FITM2, and G0S2 are under direct transcriptional control of PPARs. Upregulation of LD-associated proteins by PPARs provides a mechanism to link uptake of lipids to regulation of lipid storage capacity. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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•Most cell types carry lipid droplets and lipid droplet-associated proteins.•PPARs are master regulators of lipid metabolism in various cell types.•The three PPARs differ in their ligand specificity and in their expression profile across tissues.•PPARs play a key role in the regulation of the expression of LD-associated proteins.•The expression level of LD-associated proteins and the regulation by PPARs is cell type specific.
Magnetic signals in igneous rocks arise from assemblages of iron‐oxide bearing minerals that differ in for example, size, shape, and chemistry. Paleomagnetic measurements on bulk samples measure ...millions of such grains simultaneously, producing a statistical ensemble of the magnetic moments of the individual grains. Scanning magnetometry techniques such as the Quantum Diamond Microscope (QDM) measure magnetic signals on micrometer scales, allowing the identification of magnetic moments of individual grains in a sample using for example, Micromagnetic Tomography (MMT). Here we produce a grain‐size distribution of iron‐oxides in a typical Hawaiian basalt from the superparamagnetic threshold (∼40 nm) to grains with a diameter of 10 µm. This grain‐size distribution is obtained by combining FIB‐SEM and MicroCT data from sister specimens, and normalizing them to the mineral surface area of non‐magnetic minerals. Then we use this grain‐size distribution to determine the contributions of individual magnetic carriers to bulk magnetic measurements and surface magnetometry. We found that measurements on bulk samples are sensitive to relatively small grain sizes in the realm of single domain or vortex states (<200 nm), while signals in surface magnetometry arise mainly from larger grains with diameters >1 µm. This implies that bulk measurements cannot be compared straightforwardly to signals from surface magnetometry from the same sample. Moreover, our observations explain why MMT results are insensitive to the presence of many small grains in a sample that intuitively should hamper their outcome.
Plain Language Summary
Magnetic grains in lavas acquire a magnetic signal while cooling in presence of Earth's magnetic field. However, not all grains preserve the signal well, meaning that both good and bad recorders are present. Classical paleomagnetic techniques measure the magnetic signal of all recorders together, that is, the bulk signal. New scanning magnetometry techniques such as Micromagnetic Tomography acquire the signal from individual recorders in the lava, enabling the selection of potentially good recorders and the rejection of signals from bad recorders. Here we found that these two types of magnetic measurements do not measure the same grains that are present in the sample: classical techniques emphasize small grains (<200 nm), while signals in surface magnetometry arise mainly from larger grains with diameters >1 μm. This means that measurements from both techniques performed on the same sample material cannot be compared straightforwardly. Furthermore, our results explain why Micromagnetic Tomography results often are successful, even when many small magnetic grains that intuitively should hamper this technique are present in a sample.
Key Points
We determine contributions of individual magnetic carriers to bulk magnetic measurements and surface magnetometry
Measurements on bulk samples are sensitive to small grains (<200 nm); surface magnetometry emphasizes signals from larger grains (>1 μm)
Our observations explain why undetected ghost grains in MMT experiments have an unintuitively low impact on the accuracy of MMT results
Probiotics are live microorganisms that confer a number of health benefits when consumed in adequate amounts, mostly due to improvement of intestinal microflora. Bacterial strains from the genera ...Lactobacillus, Bifidobacterium, and Bacillus have been widely studied and are used to prepare ready‐to‐eat foods. However, the physicochemical stability and bioavailability of these bacteria have represented a challenge for many years, particularly in nonrefrigerated foodstuffs. Microencapsulation (ME) helps to improve the survival of these bacteria because it protects them from harsh conditions, such as high temperature, pH, or salinity, during the preparation of a final food product and its gastrointestinal passage. The most common coating materials used in the ME of probiotics are ionic polysaccharides, microbial exopolysaccharides, and milk proteins, which exhibit different physicochemical features as well as mucoadhesion. Structurally, the survival of improved bacteria depends on the quantity and strength of the functional groups located in the bacterial cell walls, coating materials, and cross‐linkers. However, studies addressing the role of these interacting groups and the resulting metabolic impacts are still scarce. The fate of new probiotic‐based products for the 21st century depends on the correct selection of the bacterial strain, coating material, preparation technique, and food vehicle, which are all briefly reviewed in this article.
Amaranth seeds are rich in protein with a high nutritional value, but little is known about their bioactive compounds that could benefit health. The objectives of this research were to investigate ...the presence, characterization, and the anticarcinogenic properties of the peptide lunasin in amaranth seeds. Furthermore, to predict and identify other peptides in amaranth seed with potential biological activities. ELISA showed an average concentration of 11.1 µg lunasin equivalent/g total extracted protein in four genotypes of mature amaranth seeds. Glutelin fraction had the highest lunasin concentration (3.0 µg/g). Lunasin was also identified in albumin, prolamin and globulin amaranth protein fractions and even in popped amaranth seeds. Western blot analysis revealed a band at 18.5 kDa, and MALDI-TOF analysis showed that this peptide matched more than 60% of the soybean lunasin peptide sequence. Glutelin extracts digested with trypsin, showed the induction of apoptosis against HeLa cells. Prediction of other bioactive peptides in amaranth globulins and glutelins were mainly antihypertensive. This is the first study that reports the presence of a lunasin-like peptide and other potentially bioactive peptides in amaranth protein fractions.
Access to genetically encoded data depends on the dynamics of DNA-binding proteins searching for specific target sites in the genome. This search process is thought to occur by facilitated ...diffusion—a combination of three-dimensional diffusion and one-dimensional sliding. Although facilitated diffusion is capable of significantly speeding up the search in vitro, the importance of this mechanism in vivo remains unclear. We use numeric simulations and analytical theory to model the target-search dynamics of DNA-binding proteins under a wide range of conditions. Our models reproduce experimental measurements of search-rate enhancement within bulk in vitro experiments, as well as the target search time for transcription factors measured in vivo. We find that facilitated diffusion can accelerate the search process only for a limited range of parameters and only under dilute DNA conditions. We address the role of DNA configuration and confinement, demonstrating that facilitated diffusion does not speed up the search on coiled versus straight DNA. Furthermore, we show that, under in vivo conditions, the search process becomes effectively diffusive and is independent of DNA configuration. We believe our results cast in a new light the role of facilitated diffusion in DNA targeting kinetics within the cell.
•Influence of the aggregates’ crushing process on the concrete’s (RAC) performance.•Influence on concrete mechanical properties of coarse aggregates from concrete waste.•Influence of two types of ...superplasticizer (average and high water-reducing capacity).•Relative efficiency of superplasticizers in RAC compared with conventional concrete.
Waste management has become vitally important since the demand for natural resources and the amount of construction and demolition waste have greatly increased, putting huge pressure on the environment. The main goal of this study is to evaluate the effects of the introduction of superplasticizers on some mechanical properties of concrete with recycled concrete aggregates and compare them with the corresponding properties of conventional concrete made with natural aggregates. The experimental program is described and the results of workability, specific density, compressive strength, splitting tensile strength and abrasion resistance tests carried out on concrete are presented. Two different crushing processes and their effects on aggregate properties were tested. By varying the replacement percentage of natural by recycled aggregates, with or without the addition of superplasticizers, it was possible to identify some weaknesses and strengths of the recycled aggregates concrete which can contribute to developing the more widespread use of this material.
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