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1.
Use of Enzymes in Dairy Industry: A Review of Current Progress.
Khan, U, Selamoglu, Z
Archives of Razi Institute. 2020;(1):131-136
Abstract
This review paper aimed to provides precious information about the function and use of different enzymes in dairy food applications. An enzyme is called a protein and catalyzes a specific reaction. Every enzyme is intended to initiate a particular reaction with a specific outcome. Moreover, numerous enzymes are present in the human body. Dairy food applications include the use of different enzymes, such as protease, to lessen the allergic properties of bovine milk products and lipase to improve the flavor of the cheese. Caseins, which are acid-soluble, are free from a flavor and can be suitable for addition to beverages and acidy foods by the limitation of proteolysis. The hydrolysates of casein are better to use in foods based on milk proteins for newborn children with allergy to bovine milk. Lipolysis makes a significant role in the flavor of Swiss cheese. The peppery flavor of Blue cheese is produced by short-chain unsaturated fats and methyl ketones. Many minor enzymes with limited application in dairy processes are sulphydryl oxidase, lactoperoxidase, glucose oxidase, catalase, lysozyme, and superoxide dismutase. Both catalase and glucose oxidase are utilized in food preservation processes. The scope minor enzymes in milk products needed for better production of dairy products and for the future of dairy technology. The worldwide market for the production of microbial enzymes used in dairy products processing is impressively increasing; however, there are a limited number of enzyme-producing industries in the market. The production of proteinase, lactase, lipase, and microbial rennet is increasing in the laboratory and small scales. In near future, the need for these enzymes will be undoubtedly significantly increasing essentially due to the requirement of significant nutritional valuable dairy products in the country to overcome malnutrition and obesity and shift toward low-fat and healthy foods.
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2.
Advances in Enzymatic Synthesis of D-Amino Acids.
Pollegioni, L, Rosini, E, Molla, G
International journal of molecular sciences. 2020;(9)
Abstract
In nature, the D-enantiomers of amino acids (D-AAs) are not used for protein synthesis and during evolution acquired specific and relevant physiological functions in different organisms. This is the reason for the surge in interest and investigations on these "unnatural" molecules observed in recent years. D-AAs are increasingly used as building blocks to produce pharmaceuticals and fine chemicals. In past years, a number of methods have been devised to produce D-AAs based on enantioselective enzymes. With the aim to increase the D-AA derivatives generated, to improve the intrinsic atomic economy and cost-effectiveness, and to generate processes at low environmental impact, recent studies focused on identification, engineering and application of enzymes in novel biocatalytic processes. The aim of this review is to report the advances in synthesis of D-AAs gathered in the past few years based on five main classes of enzymes. These enzymes have been combined and thus applied to multi-enzymatic processes representing in vitro pathways of alternative/exchangeable enzymes that allow the generation of an artificial metabolism for D-AAs synthetic purposes.
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3.
Starch-guest inclusion complexes: Formation, structure, and enzymatic digestion.
Tan, L, Kong, L
Critical reviews in food science and nutrition. 2020;(5):780-790
Abstract
Starch/amylose-guest inclusion complexes, a class of supramolecular host-guest assemblies, are of critical importance in the processing, preservation, digestion, nutrients/energy uptake, and health outcomes of starch-containing foods. Particularly, the formation of inclusion complex has been suggested to lower the rate and extent of enzymatic digestion of starch and starch-containing foods. Compared with rapidly digestible starch, starch inclusion complex may fall into the category of slowly digestible starch, providing sustained glucose release and maintaining glucose homeostasis. Therefore, the ability of starch-guest inclusion complex to alter the digestive behavior of energy-dense starchy foods has been of interest to many researchers and has the potential to be developed and formulated into functional foods. In this article, we provide a comprehensive and critical review on the current knowledge of the in vitro and in vivo enzymatic digestion of starch-guest inclusion complexes, by emphasizing the structure-digestibility relationship. We examine the preparation methods employed, crystalline structures obtained, and physicochemical properties characterized in previous reports, which all have implications on the digestive behavior reported on the starch-guest inclusion complexes. In addition, we give suggestions on future research to elucidate the digestive properties of starch-guest inclusion complexes and to develop functional structures based on these complexes for use in foods and nutrition.
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4.
Enzymatic assays for the assessment of toxic effects of halogenated organic contaminants in water and food. A review.
Artabe, AE, Cunha-Silva, H, Barranco, A
Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association. 2020;:111677
Abstract
Halogenated organic compounds are a particular group of contaminants consisting of a large number of substances, and of great concern due to their persistence in the environment, potential for bioaccumulation and toxicity. Some of these compounds have been classified as persistent organic pollutants (POPs) under The Stockholm Convention and many toxicity assessments have been conducted on them previously. In this work we provide an overview of enzymatic assays used in these studies to establish toxic effects and dose-response relationships. Studies in vivo and in vitro have been considered with a particular emphasis on the impact of halogenated compounds on the activity of relevant enzymes to the humans and the environment. Most information available in the literature focuses on chlorinated compounds, but brominated and fluorinated molecules are also the target of increasing numbers of studies. The enzymes identified can be classified as enzymes: i) the activities of which are affected by the presence of halogenated organic compounds, and ii) those involved in their metabolisation/detoxification resulting in increased activities. In both cases the halogen substituent seems to have an important role in the effects observed. Finally, the use of these enzymes in biosensing tools for monitoring of halogenated compounds is described.
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5.
The "cold revolution". Present and future applications of cold-active enzymes and ice-binding proteins.
Mangiagalli, M, Brocca, S, Orlando, M, Lotti, M
New biotechnology. 2020;:5-11
Abstract
Psychrophilic organisms adapted to cold environments produce molecules of relevance for biotechnological application, in particular enzymes active at low temperatures and ice-binding proteins that control the growth of ice crystals. The use of cold-active enzymes supports low temperature processes that preserve heat labile compounds and can result, in some circumstances, in energy saving. Among the several possible applications in biotransformations, this paper focuses on reactions of relevance for the food industry and in molecular biology, representative of different market segments. Ice-binding proteins reduce tissues damage provoked by ice crystals and are therefore of relevance for frozen foods and for the cryopreservation of organs and tissues in the biomedical sector.
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6.
Structural basis of ergothioneine biosynthesis.
Stampfli, AR, Blankenfeldt, W, Seebeck, FP
Current opinion in structural biology. 2020;:1-8
Abstract
Ergothioneine is a sulfur-containing histidine derivative synthesized by many bacteria and most fungi but it also finds its way into human tissue by way of specific absorption from the diet. The precise role of ergothioneine is not yet known but there is growing evidence that it plays a role as an antioxidant protecting human cells from oxidative stress and pathogenic bacteria from host defenses. In this review we highlight recent advances in understanding the structural basis of ergothioneine biosynthesis. In addition to unusual carbon-sulfur bond forming enzymology this research has revealed that ergothioneine biosynthesis has emerged at least three times by independent molecular evolution.
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7.
Adenosylation reactions catalyzed by the radical S-adenosylmethionine superfamily enzymes.
Ding, W, Ji, X, Zhong, Y, Xu, K, Zhang, Q
Current opinion in chemical biology. 2020;:86-95
Abstract
The radical S-adenosylmethionine (SAM) superfamily enzymes reductively cleave SAM to produce a highly reactive 5'-deoxyadenosyl (dAdo) radical, which in most cases abstracts a hydrogen from the substrate and initiates highly diverse reactions. In rare cases, the dAdo radical can add to a sp2 carbon to result in the production an adenosylated product. These radical SAM-dependent adenosylation reactions are present in natural product biosynthetic pathways and can be achieved by using unnatural substrate analogs containing olefin or aryl moieties. This Opinion provides a focused perspective on this emerging type of biochemistry and discusses its potential use in bioengineering and biocatalysis.
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8.
Molecular Modeling of Epithiospecifier and Nitrile-Specifier Proteins of Broccoli and Their Interaction with Aglycones.
Román, J, González, D, Inostroza, M, Mahn, A
Molecules (Basel, Switzerland). 2020;(4)
Abstract
Glucosinolates are secondary plant metabolites of Brassicaceae. They exert their effect after enzymatic hydrolysis to yield aglycones, which become nitriles and epithionitriles through the action of epithiospecifier (ESP) and nitrile-specifier proteins (NSP). The mechanism of action of broccoli ESP and NSP is poorly understood mainly because ESP and NSP structures have not been completely characterized and because aglycones are unstable, thus hindering experimental measurements. The aim of this work was to investigate the interaction of broccoli ESP and NSP with the aglycones derived from broccoli glucosinolates using molecular simulations. The three-dimensional structure of broccoli ESP was built based on its amino-acid sequence, and the NSP structure was constructed based on a consensus amino-acid sequence. The models obtained using Iterative Threading ASSEmbly Refinement (I-TASSER) were refined with the OPLS-AA/L all atom force field of GROMACS 5.0.7 and were validated by Veryfy3D and ERRAT. The structures were selected based on molecular dynamics simulations. Interactions between the proteins and aglycones were simulated with Autodock Vina at different pH. It was concluded that pH determines the stability of the complexes and that the aglycone derived from glucoraphanin has the highest affinity to both ESP and NSP. This agrees with the fact that glucoraphanin is the most abundant glucosinolate in broccoli florets.
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9.
Pictet-Spenglerases in alkaloid biosynthesis: Future applications in biocatalysis.
Roddan, R, Ward, JM, Keep, NH, Hailes, HC
Current opinion in chemical biology. 2020;:69-76
Abstract
Pictet-Spenglerases provide a key role in the biosynthesis of many biologically active alkaloids. There is increasing use of these biocatalysts as an alternative to traditional organic synthetic methods as they provide stereoselective and regioselective control under mild conditions. Products from these enzymes also contain privileged drug scaffolds (such as tetrahydroisoquinoline or β-carboline moieties), so there is interest in the characterization and use of these enzymes as versatile biocatalysts to synthesize analogs of the corresponding natural products for drug discovery. This review discusses all known Pictet-Spenglerase enzymes and their applications as biocatalysts.
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10.
Chlorination versus hydroxylation selectivity mediated by the non-heme iron halogenase WelO5.
Zhang, X, Wang, Z, Gao, J, Liu, W
Physical chemistry chemical physics : PCCP. 2020;(16):8699-8712
Abstract
The selectivity of halogenation versus hydroxylation in α-KG de-pendent halogenases is vital to their function and has been widely studied, particularly using the halogenase SyrB2 as a model. WelO5, a new member of α-KG dependent halogenases, catalyzes the chlorination of 12-epi-fischerindole U in the welwitindolinone biosynthetic pathway. Herein, we give a detailed insight into the selectivity of WelO5 through combined quantum mechanical/molecular mechanical (QM/MM) calculations for the whole catalytic cycle. O2 activation leads to a Fe(iv)[double bond, length as m-dash]O moiety which adopts an equatorial conformation (in the plane consisting of His164, chloride and Fe atom), in contrast to axial conformation (perpendicular to the plane). Key to the conformational selectivity is a serine residue (Ser189) in the equatorial plane, that brings the precursor of the Fe(iv)[double bond, length as m-dash]O intermediate (a Fe(ii)-peracid complex) to the equatorial conformation through hydrogen bonding. Hydrogen abstraction of the substrate by the equatorial Fe(iv)[double bond, length as m-dash]O leads to a five-coordinated HO-Fe(iii)-Cl complex, where the hydroxyl ligand is still equatorial and thus relatively far from the substrate radical in the axial direction compared to the chloride ligand. This smoothly explains the extremely high selectivity of chlorination in WelO5 and provides a microscopic explanation for the experimental finding that S189A WelO5 ceases to display any chlorination selectivity versus hydroxylation. Notably, although Ser189 is vital for the selectivity of the enzyme, it is not part of the substrate binding pocket. Therefore, WelO5 serves as an excellent example how chemoselectivity can be achieved in directed evolution without the tedious redesign of the substrate binding pocket.