Review of phosphocholine substituents on bacterial pathogen glycans: Synthesis, structures and interactions with host proteins

Among the non-carbohydrate components of glycans, the addition of phosphocholine (ChoP) to the glycans of pathogens occurs more rarely than acetylation or methylation, but it has far more potent biological consequences. These arise from ChoP's multiple interactions with host proteins, which are important at all stages of the infection process. These stages include initial adherence to cells, encountering the host's innate immune system and then the adaptive immune system. Thus, in the initial stages of an infection, ChoP groups are an asset to the pathogen, but they can turn into a disadvantage subsequently. In this review, we have focussed on structural aspects of these phenomena. We describe the biosynthesis of the ChoP modification, the structures of the pathogen glycans known to carry ChoP groups and the host proteins that recognize ChoP.

The Action of Recombinant Human Lysosomal α-Glucosidase (rhGAA) on Human Liver Glycogen: Pathway to Complete Degradation

Glycogen is present in all tissues, but it is primarily stored in the liver and in muscle. As a branched chain carbohydrate, it is broken down by phosphorylase and debrancher enzymes, which are cytoplasmic. It is also degraded by a lysosomal α-glucosidase (GAA) also known as acid α-glucosidase and lysosomal acid α-glucosidase. The deficiency of GAA in patients is known as Pompe disease, and the phenotypes as infantile, juvenile and later onset forms. Pompe disease is treated by enzyme replacement therapy (ERT) with a recombinant form of rhGAA. Following ERT in Pompe mice and human patients there is residual carbohydrate material present in the cytoplasm of cells. The goal of this work is to improve ERT and attempt to identify and treat the residual cytoplasmic carbohydrate. Initial experiments were to determine if rhGAA can completely degrade glycogen. The enzyme cannot completely degrade glycogen. There is a residual glycosylated protein as well as a soluble glycosylated protein, which is a terminal degradation product of glycogen and as such serves as a biomarker for lysosomal glycogen degradation. The glycosylated protein has a very unusual carbohydrate composition for a glycosylated protein: m-inositol, s-inositol and sorbitol as the major carbohydrates, as well as mannitol, mannose, glucose and galactose. This work describes the residual material which likely contains the same protein as the soluble glycosylated protein. The biomarker is present in serum of control and Pompe patients on ERT, but it is not present in the serum of Pompe mice not on ERT. Pompe mice not on ERT have another glycosylated protein in their serum which may be a biomarker for Pompe disease. This protein has multiple glycosylation sites, each with different carbohydrate components. These glycosylated proteins as well as the complexity of glycogen structure are discussed, as well as future directions to try to improve the outcome of ERT for Pompe patients by being able to monitor the efficacy of ERT in the short term and possibly to adjust the timing and dose of enzyme infusions.

Reductive Catalytic Fractionation of Lignocellulosic Biomass: A New Promising Method of its Integrated Processing

The review discusses the results of recent studies in the promising field of integrated processing of lignocellulosic biomass – the reductive catalytic fractionation (RCF). The effect of catalysts, cocatalysts, solvents, hydrogen sources and features of lignocellulosic feedstock on the selectivity of monomeric products formation from lignin is considered. RCF processes are performed mostly with the heterogeneous catalysts, which allow implementing the reductive depolymerization of lignin to obtain low-molecular compounds and preserve carbohydrate components of biomass. Among the studied catalysts based on platinum group metals and transition metals, the highest activity is observed for the catalysts containing Pd, Pt, Ru and Ni. Features of the metal also affect the composition of the resulting products. Thus, ruthenium catalysts make it possible to obtain 4-propylguaiacol as the main product, while Ni and Pd – 4-propanolguaiacol. Mo-containing catalysts, owing to their lower hydrogenating activity, can be used to obtain monolignols or their etherified derivatives with the preservation of carbohydrate components of lignocellulosic biomass. However, most efficient in RCF processes are the bifunctional catalysts, which have both the acidic and metallic active sites. Acidic sites promote the cleavage of the ether β-O-4 bonds, whereas metallic sites – the reduction of the formed intermediate compounds. An important aspect of choosing the appropriate catalysts for RCF process is the possibility of their repeated application. The use of a ferromagnetic catalyst or a catalyst basket allows separating the catalyst from the products.

Chemical Modification of Glycoproteins’ Carbohydrate Moiety as a General Strategy for the Synthesis of Efficient Biocatalysts by Biomimetic Mineralization: The Case of Glucose Oxidase

Zeolitic imidazolate framework-8 (ZIF-8) is widely used as a protective coating to encapsulate proteins via biomimetic mineralization. The formation of nucleation centers and further biocomposite crystal growth is entirely governed by the pure electrostatic interactions between the protein’s surface and the positively charged Zn(II) metal ions. It was previously shown that enhancing these electrostatic interactions by a chemical modification of surface amino acid residues can lead to a rapid biocomposite crystal formation. However, a chemical modification of carbohydrate components by periodate oxidation for glycoproteins can serve as an alternative strategy. In the present study, an industrially important enzyme glucose oxidase (GOx) was selected as a model system. Periodate oxidation of GOx by 2.5 mM sodium periodate increased negative charge on the enzyme molecule, from −10.2 to −36.9 mV, as shown by zeta potential measurements and native PAGE electrophoresis. Biomineralization experiments with oxidized GOx resulted in higher specific activity, effectiveness factor, and higher thermostability of the ZIF-8 biocomposites. Periodate oxidation of carbohydrate components for glycoproteins can serve as a facile and general method for facilitating the biomimetic mineralization of other industrially relevant glycoproteins.

Evidence for Lignocellulose-Decomposing Enzymes in the Genome and Transcriptome of the Aquatic Hyphomycete Clavariopsis aquatica

Fungi are ecologically outstanding decomposers of lignocellulose. Fungal lignocellulose degradation is prominent in saprotrophic Ascomycota and Basidiomycota of the subkingdom Dikarya. Despite ascomycetes dominating the Dikarya inventory of aquatic environments, genome and transcriptome data relating to enzymes involved in lignocellulose decay remain limited to terrestrial representatives of these phyla. We sequenced the genome of an exclusively aquatic ascomycete (the aquatic hyphomycete Clavariopsis aquatica), documented the presence of genes for the modification of lignocellulose and its constituents, and compared differential gene expression between C. aquatica cultivated on lignocellulosic and sugar-rich substrates. We identified potential peroxidases, laccases, and cytochrome P450 monooxygenases, several of which were differentially expressed when experimentally grown on different substrates. Additionally, we found indications for the regulation of pathways for cellulose and hemicellulose degradation. Our results suggest that C. aquatica is able to modify lignin to some extent, detoxify aromatic lignin constituents, or both. Such characteristics would be expected to facilitate the use of carbohydrate components of lignocellulose as carbon and energy sources.

Mycolysis of wood, its products and their use. IV. Component analysis of mycologically destroyed wood

The article is devoted to the study of the component composition of mycologically destroyed wood. As a result of wood mycolysis under the action of wood-destroying fungi enzymes, so-called «rot» is formed with a chemical composition different from healthy wood. It is noted that the «brown rot» of wood is enriched with lignin components of wood and «white rot» with carbohydrate components of wood. The results of analyses of ligno-carbohydrate complexes of spruce wood «brown rot», birch wood «white rot» and a group study of low-molecular compounds isolated by extraction methods with various solvents are presented. It is noted that the content of lignin in the sample of «brown rot» wood is four times higher than in the sample of «white rot». It is shown that birch wood with «white rot» is significantly enriched with cellulose. The chemical nature of some groups of extractive substances has been revealed. In the extracts of mycologically destroyed wood, substances of phenolic, alcoholic and quinone nature were found. The presence of derivatives of aromatic and aliphatic carbonyl and carboxyl compounds is noted. Among the products of mycolysis, carbohydrates, flavanoids and terpenoids have been identified. Based on the analysis, an assumption is made that mycologically destroyed wood contains a wide range of phenolic and carbohydrate compounds contained both in the original wood and in the spores and hyphae of wood-destroying fungi themselves. The idea is substantiated that the study of extractive substances of mycologically destroyed wood makes it possible to predict possible directions of the prospective use of this raw material for obtaining target products. This article is the fourth in the cycle «Wood mycolysis, its products and their use», the previous ones were published in the journal «Forestry Bulletin», 2020, v. 24, no. 2, 6; v. 25, no. 1.

Possible benefits of whole goat milk in infant formulas for a healthy baby

Смеси на основе белков козьего молока для вскармливания детей первого года жизни применяются с 1980-х гг. Новое поколение детских смесей производится с использованием цельного козьего молока, в которых поддерживается естественное соотношение сывороточного белка к казеину – 20:80, сохранен молочный жир и углеводный компонент, что позволяет транслировать преимущества козьего молока на состав адаптированной смеси для приближения к составу грудного молока. Белок и молочный жир, полученные из цельного козьего молока, обладают высокой усвояемостью вследствие особенностей строения и состава: белок с низким αs1-казеином образует мягкий сгусток в желудке, что способствует легкому его перевариванию, а жировые глобулы козьего молока имеют меньшие размеры и большую площадь поверхности, сравнимую с грудным молоком. Молочный жир козьего молока в смеси является источником основных донаторов энергии – жирных кислот с короткой и средней длиной углеродной цепи, β-кетокислот, а также пальмитиновой кислоты в sn-2-положении в молекуле глицерола. В составе смеси в процессе производства сохраняются мембраны жировых глобул козьего молока. Их компоненты обладают разнообразными физиологическими функциями. Белки мембран жировых глобул козьего молока способствуют развитию микробиоты кишечника, иммунных функций, обладают антимикробным и противовирусным действием. Липиды мембран жировых глобул козьего молока улучшают барьерные функции кишечного эпителия, поддерживают его структурную целостность, а также участвуют в построении мембран клеток слизистой оболочки желудочно-кишечного тракта и быстроразвивающейся нервной ткани ребенка. В цельном козьем молоке присутствуют олигосахариды в меньшем количестве и разнообразии по сравнению с грудным молоком, что диктует необходимость дополнения детской смеси олигосахаридами или пребиотиками, повторяющими функции олигосахаридов грудного молока. Доказательства безопасности и клинической эффективности применения смесей на основе цельного козьего молока в обеспечении правильного роста и развития детей первых месяцев жизни представлены в клинических исследованиях. Goat milk protein-based formulas for feeding babies of the first year of life have been used since the 80s of the last century. A new generation of infant formula is made using whole goat milk, in which the natural ratio of whey protein: casein is maintained at 20:80, milk fat and carbohydrate components are preserved, which allows translating the benefits of goat milk into an adapted formula to approximate the composition of breast milk (BM). Protein and milk fat obtained from whole goat milk are highly digestible due to the structural and compositional characteristics: protein with low αs1-casein forms a soft clot in the stomach, which facilitates its easy digestion, and the fat globules of goat milk are smaller and larger surface area comparable to BM. Goat milk fat in the formula is the source of the main donor energy – fatty acids with a short and medium carbon chain length, β-keto acids, and palmitic acid in the sn-2-position in the glycerol molecule. In the composition of the formula during the production process, the goat's milk fat globules membranes (MFGM) are preserved. The components of MFGM have different physiological functions. MFGM proteins contribute to the development of intestinal microbiota, immune functions, have antimicrobial and antiviral effects. Lipids MFGM improve the barrier functions of the intestinal epithelium, maintain its structural integrity, and also participate in the construction of cell membranes of the mucous membrane of the gastrointestinal tract and the rapidly developing nervous tissue of the child. In whole goat milk, oligosaccharides (OS) are present in a smaller amount and variety in comparison with BM, which dictates the need to supplement the infant formula with OS or prebiotics that repeat the functions of BM OG. Clinical studies have shown evidence of the safety and clinical efficacy of using whole goat milk formulas in promoting the proper growth and development of infants in their first months of life.

Effect of storage time and the level of formic acid on fermentation characteristics, epiphytic microflora, carbohydrate components and in vitro digestibility of rice straw silage

Objective: The study aimed to evaluate the effect of storage time and formic acid (FA) on fermentation characteristics, epiphytic microflora, carbohydrate components and <i>in vitro</i> digestibility of rice straw silage.Methods: Fresh rice straw was ensiled with four levels of FA (0%, 0.2%, 0.4%, and 0.6% of fresh weight) for 3, 6, 9, 15, 30, and 60 d. At each time point, the silos were opened and sampled for chemical and microbial analyses. Meanwhile, the fresh and 60-d ensiled rice straw were further subjected to <i>in vitro</i> analyses.Results: The results showed that 0.2% and 0.6% FA both produced well-preserved silages with low pH value and undetected butyric acid, whereas it was converse for 0.4% FA. The populations of enterobacteria, yeasts, moulds and aerobic bacteria were suppressed by 0.2% and 0.6% FA, resulting in lower dry matter loss, ammonia nitrogen and ethanol content (p<0.05). The increase of FA linearly (p<0.001) decreased neutral detergent fibre and hemicellulose, linearly (p<0.001) increased residual water soluble carbohydrate, glucose, fructose and xylose. The <i>in vitro</i> gas production of rice straw was decreased by ensilage but the initial gas production rate was increased, and further improved by FA application (p<0.05). No obvious difference of FA application on <i>in vitro</i> digestibility of dry matter, neutral detergent fibre, and acid detergent fibre was observed (p>0.05).Conclusion: The 0.2% FA application level promoted lactic acid fermentation while 0.6% FA restricted all microbial fermentation of rice straw silages. Rice straw ensiled with 0.2% FA or 0.6% FA improved its nutrient preservation without affecting digestion, with the 0.6% FA level best.

Review of phosphocholine substituents on bacterial pathogen glycans: Synthesis, structures and interactions with host proteins

Among the non-carbohydrate components of glycans, the addition of phosphocholine (ChoP) to the glycans of pathogens occurs more rarely than acetylation or methylation, but it has far more potent biological consequences. These arise from ChoP's multiple interactions with host proteins, which are important at all stages of the infection process. These stages include initial adherence to cells, encountering the host's innate immune system and then the adaptive immune system. Thus, in the initial stages of an infection, ChoP groups are an asset to the pathogen, but they can turn into a disadvantage subsequently. In this review, we have focussed on structural aspects of these phenomena. We describe the biosynthesis of the ChoP modification, the structures of the pathogen glycans known to carry ChoP groups and the host proteins that recognize ChoP.

Review of phosphocholine substituents on bacterial pathogen glycans: Synthesis, structures and interactions with host proteins

Among the non-carbohydrate components of glycans, the addition of phosphocholine (ChoP) to the glycans of pathogens occurs more rarely than acetylation or methylation, but it has far more potent biological consequences. These arise from ChoP's multiple interactions with host proteins, which are important at all stages of the infection process. These stages include initial adherence to cells, encountering the host's innate immune system and then the adaptive immune system. Thus, in the initial stages of an infection, ChoP groups are an asset to the pathogen, but they can turn into a disadvantage subsequently. In this review, we have focussed on structural aspects of these phenomena. We describe the biosynthesis of the ChoP modification, the structures of the pathogen glycans known to carry ChoP groups and the host proteins that recognize ChoP.