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1.
The new place of enterohormones in intestinal failure.
Daoud, DC, Joly, F
Current opinion in clinical nutrition and metabolic care. 2020;(5):344-349
Abstract
PURPOSE OF REVIEW Since the approval of teduglutide, a glucagon-like peptide-2 (GLP-2) analog, for the treatment of patients with short bowel syndrome (SBS) associated with intestinal failure, enterohormone therapy has received significant interest and is becoming the first choice of treatment in selected patients. As such, it is paramount to assess and understand the new place of hormonal therapy in the algorithm of treatments in SBS-intestinal failure. RECENT FINDINGS Specialized intestinal failure units have recently reported their outcomes with teduglutide to evaluate if they are consistent with the phase III trials results. SBS-intestinal failure patients are very heterogenous including their response to this treatment, hence the importance of real-life studies beyond the context of clinical trials. Moreover, it is essential to find a consensus on criteria identifying candidate patients for teduglutide. In addition, the impact of teduglutide on quality of life and its cost-effectiveness are emerging as well as new enterohormone treatments are being studied whether it is long action GLP-2 analog or other ileocolonic break hormones like glucagon-like peptide-1 analog. SUMMARY Hormonotherapy is currently modifying the natural history of patients with SBS-intestinal failure by decreasing their need for parenteral support and possibly even complications associated with long-term parenteral support. Enterohormone treatment is now the cornerstone in SBS-intestinal failure and should be offered as a first-line therapy to selected patients.
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Food protein-derived iron-chelating peptides: The binding mode and promotive effects of iron bioavailability.
Wu, W, Yang, Y, Sun, N, Bao, Z, Lin, S
Food research international (Ottawa, Ont.). 2020;:108976
Abstract
Iron is known as an essential nutrient in the human body. Insufficient iron uptake is easy to result in iron deficiency anemia, which is a public health problem in both developing and developed countries. Iron, complexed by iron-chelating peptides, have been proposed as a superior candidate to ionized iron for improving iron absorption and bioavailability. Nowadays, as more and more iron-chelating peptides are identified from different food sources, the iron-peptide binding mode attracts much attention. Meanwhile, many studies have been conducted on the iron-chelating peptides to make clear their iron bioavailability enhancement potential. The aim of this review is to provide an overview of research progress in food protein-derived iron-chelating peptides. The review would be of particular value for iron-peptide complexes as functional ingredients or iron supplements.
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3.
Recent trends in peptide and protein-based hydrogels.
Katyal, P, Mahmoudinobar, F, Montclare, JK
Current opinion in structural biology. 2020;:97-105
Abstract
Hydrogels are classic examples of biomaterials that have found its niche in biomedical and allied fields. Here, we describe examples of peptide-based and protein-based hydrogels with a focus on smart gels that respond to various stimuli including temperature, pH, light, and ionic strength. With the recent advancements in computational modeling, it has been possible to predict as well as design peptide and protein sequences that can assemble into hydrogels with unique and improved properties. We briefly discuss coarse grained and atomistic simulations in designing peptides that can form hydrogels. In addition, we highlight the trends that will influence the future design and applications of hydrogels, with emphasis on bioadhesion, exosomes delivery, tissue and organoids engineering, and even intracellular production of gels.
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4.
Use of Alcalase in the production of bioactive peptides: A review.
Tacias-Pascacio, VG, Morellon-Sterling, R, Siar, EH, Tavano, O, Berenguer-Murcia, Á, Fernandez-Lafuente, R
International journal of biological macromolecules. 2020;(Pt B):2143-2196
Abstract
This review aims to cover the uses of the commercially available protease Alcalase in the production of biologically active peptides since 2010. Immobilization of Alcalase has also been reviewed, as immobilization of the enzyme may improve the final reaction design enabling the use of more drastic conditions and the reuse of the biocatalyst. That way, this review presents the production, via Alcalase hydrolysis of different proteins, of peptides with antioxidant, angiotensin I-converting enzyme inhibitory, metal binding, antidiabetic, anti-inflammatory and antimicrobial activities (among other bioactivities) and peptides that improve the functional, sensory and nutritional properties of foods. Alcalase has proved to be among the most efficient proteases for this goal, using different protein sources, being especially interesting the use of the protein residues from food industry as feedstock, as this also solves nature pollution problems. Very interestingly, the bioactivities of the protein hydrolysates further improved when Alcalase is used in a combined way with other proteases both in a sequential way or in a simultaneous hydrolysis (something that could be related to the concept of combi-enzymes), as the combination of proteases with different selectivities and specificities enable the production of a larger amount of peptides and of a smaller size.
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5.
Late-Stage Diversification of Tryptophan-Derived Biomolecules.
Gruß, H, Sewald, N
Chemistry (Weinheim an der Bergstrasse, Germany). 2020;(24):5328-5340
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Abstract
Pd-mediated reactions have emerged as a powerful tool for the site-selective and bioorthogonal late-stage diversification of amino acids, peptides and related compounds. Indole moieties of tryptophan derivatives are susceptible to C2 H-activation, whereas halogenated aromatic amino acids such as halophenylalanines or halotryptophans provide a broad spectrum of different functionalisations. The compatibility of transition-metal-catalysed cross-couplings with functional groups in peptides, other biologically active compounds and even proteins has been demonstrated. This Review primarily compiles the application of different cross-coupling reactions to modify halotryptophans, halotryptophan containing peptides or halogenated, biologically active compounds derived from tryptophan. Modern approaches use regio- and stereoselective biocatalytic strategies to generate halotryptophans and derivatives on a preparative scale. The combination of bio- and chemocatalysis in cascade reactions is given by the biocompatibility and bioorthogonality of Pd-mediated reactions.
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Use of Non-Pharmacological Supplementations in Children and Adolescents with Attention Deficit/Hyperactivity Disorder: A Critical Review.
Rosi, E, Grazioli, S, Villa, FM, Mauri, M, Gazzola, E, Pozzi, M, Molteni, M, Nobile, M
Nutrients. 2020;(6)
Abstract
Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children and adolescents, with environmental and biological causal influences. Pharmacological medication is the first choice in ADHD treatment; recently, many studies have concentrated on dietary supplementation approaches to address nutritional deficiencies, to which part of non-responses to medications have been imputed. This review aims to evaluate the efficacy of non-pharmacological supplementations in children or adolescents with ADHD. We reviewed 42 randomized controlled trials comprised of the following supplementation categories: polyunsaturated fatty acids (PUFAs), peptides and amino acids derivatives, single micronutrients, micronutrients mix, plant extracts and herbal supplementations, and probiotics. The reviewed studies applied heterogeneous methodologies, thus making it arduous to depict a systematic overview. No clear effect on single cognitive, affective, or behavioral domain was found for any supplementation category. Studies on PUFAs and micronutrients found symptomatology improvements. Peptides and amino acids derivatives, plant extracts, herbal supplementation, and probiotics represent innovative research fields and preliminary results may be promising. In conclusion, such findings, if confirmed through future research, should represent evidence for the efficacy of dietary supplementation as a support to standard pharmacological and psychological therapies in children and adolescents with ADHD.
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Chemoselective Methionine Bioconjugation on a Polypeptide, Protein, and Proteome.
Zang, J, Chen, Y, Zhu, W, Lin, S
Biochemistry. 2020;(2):132-138
Abstract
Methionine is one of the most hydrophobic, redox-sensitive, and one of the only two sulfur-containing amino acids on protein. Because of these biochemical properties, the methionine residue plays a central role in a variety of biological processes, such as metal coordination, antioxidant stress, and aging. However, studies on the molecular functions of methionine are much less common than the other primary sulfur-containing amino acid, cysteine. The limited number of publications on methionine-related studies is partially due to the lack of tools for methionine modification. Methionine bioconjugation offers a new strategy to decipher the biological function of methionine and expands the toolbox for protein functionalization in the context of the application, such as synthesizing proteins with novel properties and producing new biomaterials. The purpose of this Perspective is to highlight the biochemical properties and functions of methionine, list recent progress in the development of methionine bioconjugation reagents, and briefly demonstrate the application of these reagents on polypeptides, proteins, and proteomes.
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Current Approaches in Diabetes Treatment and Other Strategies to Reach Normoglycemia.
Sirhan, W, Piran, R
Current topics in medicinal chemistry. 2020;(32):2922-2944
Abstract
Cells are mainly dependent on glucose as their energy source. Multicellular organisms need to adequately control individual glucose uptake by the cells, and the insulin-glucagon endocrine system serves as the key glucose regulation mechanism. Insulin allows for effective glucose entry into the cells when blood glucose levels are high, and glucagon acts as its opponent, balancing low blood glucose levels. A lack of insulin will prevent glucose entry to the cells, resulting in glucose accumulation in the bloodstream. Diabetes is a disease which is characterized by elevated blood glucose levels. All diabetes types are characterized by an inefficient insulin signaling mechanism. This could be the result of insufficient insulin secretion, as in the case of type I diabetes and progressive incidents of type II diabetes or due to insufficient response to insulin (known as insulin resistance). We emphasize here, that Diabetes is actually a disease of starved tissues, unable to absorb glucose (and other nutrients), and not a disease of high glucose levels. Indeed, diabetic patients, prior to insulin discovery, suffered from glucose malabsorption. In this mini-review, we will define diabetes, discuss the current status of diabetes treatments, review the current knowledge of the different hormones that participate in glucose homeostasis and the employment of different modulators of these hormones. As this issue deals with peptide therapeutics, special attention will be given to synthetic peptide analogs, peptide agonists as well as antagonists.
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Retention Time Prediction and Protein Identification.
Henneman, A, Palmblad, M
Methods in molecular biology (Clifton, N.J.). 2020;:115-132
Abstract
In bottom-up proteomics, proteins are typically identified by enzymatic digestion into peptides, tandem mass spectrometry and comparison of the tandem mass spectra with those predicted from a sequence database for peptides within measurement uncertainty from the experimentally obtained mass. Although now decreasingly common, isolated proteins or simple protein mixtures can also be identified by measuring only the masses of the peptides resulting from the enzymatic digest, without any further fragmentation. Separation methods such as liquid chromatography and electrophoresis are often used to fractionate complex protein or peptide mixtures prior to analysis by mass spectrometry. Although the primary reason for this is to avoid ion suppression and improve data quality, these separations are based on physical and chemical properties of the peptides or proteins and therefore also provide information about them. Depending on the separation method, this could be protein molecular weight (SDS-PAGE), isoelectric point (IEF), charge at a known pH (ion exchange chromatography), or hydrophobicity (reversed phase chromatography). These separations produce approximate measurements on properties that to some extent can be predicted from amino acid sequences. In the case of molecular weight of proteins without posttranslational modifications this is straightforward: simply add the molecular weights of the amino acid residues in the protein. For IEF, charge and hydrophobicity, the order of the amino acids, and folding state of the peptide or protein also matter, but it is nevertheless possible to predict the behavior of peptides and proteins in these separation methods to a degree which renders such predictions useful. This chapter reviews the topic of using data from separation methods for identification and validation in proteomics, with special emphasis on predicting retention times of tryptic peptides in reversed-phase chromatography under acidic conditions, as this is one of the most commonly used separation methods in bottom-up proteomics.
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Mechanisms of Disulfide Bond Formation in Nascent Polypeptides Entering the Secretory Pathway.
Robinson, PJ, Bulleid, NJ
Cells. 2020;(9)
Abstract
Disulphide bonds are an abundant feature of proteins across all domains of life that are important for structure, stability, and function. In eukaryotic cells, a major site of disulphide bond formation is the endoplasmic reticulum (ER). How cysteines correctly pair during polypeptide folding to form the native disulphide bond pattern is a complex problem that is not fully understood. In this paper, the evidence for different folding mechanisms involved in ER-localised disulphide bond formation is reviewed with emphasis on events that occur during ER entry. Disulphide formation in nascent polypeptides is discussed with focus on (i) its mechanistic relationship with conformational folding, (ii) evidence for its occurrence at the co-translational stage during ER entry, and (iii) the role of protein disulphide isomerase (PDI) family members. This review highlights the complex array of cellular processes that influence disulphide bond formation and identifies key questions that need to be addressed to further understand this fundamental process.