scholarly journals Effect of Different Ligand and Different Ligand Heterometal Xylaratohermanates on the Activity of α-L-Rhamnosidases Eupenicillium erubescens, Cryptococcus albidus and Penicillium tardum

2021 ◽  
Vol 83 (3) ◽  
pp. 35-45
Author(s):  
O.V. Gudzenko ◽  
◽  
N.V. Borzova ◽  
L.D. Varbanets ◽  
I.I. Seifullina ◽  
...  

α-L-Rhamnosidase [EC 3.2.1.40], enzyme of the hydrolase family has a wide range of applications: in the food industry, for example, in winemaking to improve the quality and aroma of wines, in the production of citrus juices and drinks to remove bitter components (naringin) that improves the quality and nutritional value of these products; in research as an analytical tool for studying the structure of complex carbohydrate-substituted biopolymers. For the successful use of α-L-rhamnosidases in various biotechnological processes, an important aspect is the development of ways to increase their activity. The main factors affecting the growth and metabolism of microorganisms, including the synthesis of enzymes, are the physicochemical conditions of cultivation, the composition of the nutrient medium, the introduction of substances that raise the yield of the enzyme, which is manifested in an increase in its activity. At present, one of the priority directions of modern research is the study of the effect of various effector compounds that are capable to modify the studied enzymatic activity. In this work, which is a continuation of previous studies, a number of mixed-ligand and mixed-ligand-different-metal coordination germanium compounds of with xylaric acid (H5Xylar), 1,10-phenanthroline (Phen), 2,2-bipyridine (bipy) and ions of 3d-metals (Fe2+, Ni2+, Cu2+, Zn2+) were selected as effectors. Study of the effect of these complexes on the activity of Eupenicillium erubescens, Cryptococcus аlbidus and Penicillium tardum α-L-rhamnosidases were the aim of this work. Methods. The objects of research were α-Lrhamnosidases from Eupenicillium erubescens 248, Cryptococcus albidus 1001, and Penicillium tardum IMV F-100074. The α-L-rhamnosidase activity was determined by the Davis method using naringin as a substrate. We used 12 coordination compounds of germanium as modifiers of enzyme activity, the composition and structure of which were established using a combination of physical and chemical research methods: elemental analysis, thermogravimetry, IR spectroscopy and X-ray structural analysis. Structures of seven compounds are deposited in the Cambridge Crystallographic Database. When studying the effect of various compounds on the activity of enzymes, concentrations of 0.1 and 0.01% were used, exposure times were 0.5 and 24 hours. The test compounds were dissolved in 0.1% dimethyl sulfoxide. UV-spectra of absorption of native and chemical modified preparations of the enzymes were studied by spectrophotometer-fluorimeter DeNovix DS-11 in the range of 220–340 nm, concentration of the enzyme preparation 1.0 mg of protein/mL. Results. Analysis of the totality of the obtained data (exposure time 24 h, concentration 0.1%) regarding the effect of the studied compounds on the activity of E. erubescens, C. albidus and P. tardum α-L-rhamnosidases showed that the influence of the studied modifiers for the activity of α-L-rhamnosidases varies depending on the producer strain. Our data allow us to present the following series of modifiers in accordance with an increase in their effect on the activity of enzymes of different producers: E. еrubescens: 12 < 11 < 5 < 3 < 4=10 < 1 < 3 < 8 < 2 < 6 < 7; C. albidus: 10 < 11 < 12 < 9 < 3 < 1=5 < 8=4 < 2 < 6 < 7; P. tardum: 12=2 < 3 < 4 < 11 < 5 < 8 < 1 < 9 < 6 < 10 < 7. Conclusions. The results obtained allow us to conclude that compound (7)(-tris(bipyridine) nickel(II) μ-dihydroxyxylaratogermanate(IV)) is the most effective activator of α-L-rhamnosidases of all three micromycete strains, compound (6)(tris(phenanthroline)nickel(II) μ-dihydroxyxylaratogermanate(IV)) − on α-L-rhamnosidase from E. erubescens and C. albidus, while compound (10)-(copper(II) μ-dihydroxyxylaratogermanate(IV)-cuprate(II)) − only of P. tardum α-L-rhamnosidase.

2013 ◽  
Vol 85 (1) ◽  
pp. iv
Author(s):  
Jean-François Dufrêche

The 32nd International Conference on Solution Chemistry (ICSC-32) was held 28 August-2 September 2011 in La Grande Motte, France. This conference series covers a wide range of topics related to solution chemistry, such as- thermodynamics, kinetics, and structure- polymers, colloids, interfaces, and membranes- bioinorganic, biophysical, and pharmaceutical problems- supramolecular assemblies and nanostructures- analytical and environmental aspects- solvents and solutions under extreme conditionsFive plenary lectures were given: “Electrochemistry, the challenge of 21st century: From living cells to energy production”, by Dr. Christian Amatore, Paris, France; “Ultrafast studies on chemical and biological systems”, by Prof. Majed Chergui, Lausanne, Switzerland; “Modelling ionic liquids”, by Prof. Paul Madden, Oxford, UK; “Structure and dynamics of liquids and solutions in confinement”, by Prof. Toshio Yamaguchi, Fukuoka, Japan; “Natural ionic liquids and green solution chemistry”, by Prof. Dr. Werner Kunz, Regensburg, Germany.Two special lectures were given in the frame of the “Année Internationale de la Chimie”: “Solution chemistry and preservation of archeological wood: The case of Vasa”, by Prof. Ingmar Persson, Uppsala, Sweden; and “Molecular gastronomy: A solution chemistry problem”, by Hervé This, INRA, France.Twenty-one papers based on lectures presented at the ICSC-32 are included in this issue of Pure and Applied Chemistry. These contributions feature the major themes of the conference, serve as a representative view of current activities in the field of solution chemistry, and demonstrate that solutions still prove to be challenging targets for contemporary physical and chemical research.Jean-François DufrêcheConference Editor


2010 ◽  
Vol 82 (10) ◽  
pp. iv
Author(s):  
Thomas Hofer

The 31st International Conference on Solution Chemistry (ICSC-31) was held 21-25 August 2009 in Innsbruck, Austria. This conference series covers a wide range of topics related to solution chemistry, such as spectroscopy, thermodynamics, and kinetics to name just a few, addressing experimentalists and theoreticians alike.Seventeen outstanding plenary and invited lectures were given by renowned scientists. The topics of the plenaries were solution NMR stuctures of proteins (J. Wüthrich), porous coordination polymers (S. Kitagawa), ab initio-based water potentials for simulation studies (S. Xantheas), and the hydration structures of metal ions in solution (I. Persson). Additionally, 33 oral contributions were presented and two poster sessions were held. A total of 29 countries were represented in this conference. The best poster award was given to Matjaz Boncina for his poster entitled "Thermodynamics of the ion–lysozyme association". Pierre Turq presented details of the next ICSC meeting to be held in 2011 in La Grande Motte, France.Eight papers based on lectures presented at the ICSC-31 are included in this issue of Pure and Applied Chemistry. The manuscripts cover investigations using different spectroscopic approaches, molecular simulation studies as well as thermodynamic measurements. The systems treated range from pure water and aqueous solution to ionic liquids and solutions containing polyelectrolytes. These contributions feature the major themes of the conference, serve as a representative view of current activities in the field of solution chemistry, and demonstrate that solutions still prove to be challenging targets for contemporary physical and chemical research alike.Thomas HoferBernhard RandolfConference Editors


2012 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Hueyling Tan

Molecular self-assembly is ubiquitous in nature and has emerged as a new approach to produce new materials in chemistry, engineering, nanotechnology, polymer science and materials. Molecular self-assembly has been attracting increasing interest from the scientific community in recent years due to its importance in understanding biology and a variety of diseases at the molecular level. In the last few years, considerable advances have been made in the use ofpeptides as building blocks to produce biological materials for wide range of applications, including fabricating novel supra-molecular structures and scaffolding for tissue repair. The study ofbiological self-assembly systems represents a significant advancement in molecular engineering and is a rapidly growing scientific and engineering field that crosses the boundaries ofexisting disciplines. Many self-assembling systems are rangefrom bi- andtri-block copolymers to DNA structures as well as simple and complex proteins andpeptides. The ultimate goal is to harness molecular self-assembly such that design andcontrol ofbottom-up processes is achieved thereby enabling exploitation of structures developed at the meso- and macro-scopic scale for the purposes oflife and non-life science applications. Such aspirations can be achievedthrough understanding thefundamental principles behind the selforganisation and self-synthesis processes exhibited by biological systems.


1993 ◽  
Vol 32 (2) ◽  
pp. 226-228
Author(s):  
Zakir Hussain

The book; under review provides a valuable account of the issues and factors in managing the irrigation system, and presents a lucid and thorough discussion on the performance of the irrigation bureaucracies. It comprises two parts: the first outlines the factors affecting irrigation performance under a wide range of topics in the first five chapters. In Chapter One, the authors have attempted to assess the performance of the irrigation bureaucracies, conceptualise irrigation management issues, and build an empirical base for analysis while drawing upon the experience of ten country cases in Asia, Africa, and Latin America. The Second Chapter focuses on the variations in the management structures identified and the types of irrigation systems; and it defines the variables of the management structures. The activities and objectives of irrigation management are discussed in Chapter Three. The objectives include: greater production and productivity of irrigation projects; improved water distribution; reduction in conflicts; greater resource mobilisation and a sustained system performance. The authors also highlight the performance criterion in this chapter. They identify about six contextual factors which affect the objectives and the performance of irrigation, which are discussed in detail in Chapter Four. In Chapter Five, some organisational variables, which would lead to improvements in irrigation, are examined.


2020 ◽  
Vol 26 (1) ◽  
pp. 86-93
Author(s):  
D. V. Slivinsky ◽  
I. A. Fomina ◽  
D. G. Menshikh

The presented study determines the role of business aviation in the modern economy and examines the specific features of its development in Russia.Aim. The study aims to analyze the development of business aviation in Russia and its correlation with economic development in general.Tasks. The authors determine the benefits of business aviation as a business tool, examine the specific features of the Russian business aviation market and problems of its development, and identify factors that affect the development of business aviation in Russia.Methods. This study uses the methods of comparative and retrospective analysis, cross-country comparison, systems approach, and expert analytics.Results. Business aviation is a new segment of civil aviation for Russia. Therefore, it is advisable to rely on foreign practices in the management of its development. In many countries, business aviation is a separate industry that specializes in providing transport services to a wide range of corporate clients and/or individuals. The development of this industry is associated with the economic growth rate and the development level of the national economy, and also depends on the national institutional specifics. This study describes the specific features of development of business aviation in Russia and problems arising in the organization and management of this type of business.Conclusions. The authors develop a system of factors affecting the development of business aviation in Russia, describe the major problems of this industry, and propose solutions. The results of this study can be used in the development (adjustment) of business aviation development strategies in Russia both at the industrial and corporate level, and in the implementation of the national policy in this field.


2020 ◽  
Author(s):  
Salime Goharinezhad

BACKGROUND World Health Organization declared the vaccine hesitancy as a global public health threat in 2019. Since even a slight reduction in vaccine coverage rates can lead to a decrease in herd immunity, it is imperative to explore the underlying factors affecting vaccine hesitancy. in specific contexts, considering socioeconomic and cultural variation, to ensure interventions targeting hesitancy are well formulated and intervened. OBJECTIVE The main objective of this study is to identify underlying factors affecting vaccine hesitancy in Iran. METHODS A framework qualitative study will be conducted in the west of Tehran province in 2020. Participants in the study will be recruited hesitance-parents who extracted from the SIB system (an electronic health record in Iran) to maximize diversity. Interviews will be analyzed based on ''Determinants of Vaccine Hesitancy Matrix'' which developed by the WHO-SAGE Working Group. RESULTS deep understanding from the context-specific reasons for vaccine hesitancy cause to formulate better strategies to address them. The ultimate goal of this study is to inform future policies to increase the uptake of the vaccine in Iran. CONCLUSIONS This result of study will show variety opinions about vaccination among different types of socioeconomic and demographic households. The wide range of reasons related to vaccine hesitancy imply to more comprehensive, context-specific interventions. Today, the most important intervention issues focus on improving information about effectiveness and safety of vaccines, while other interventions for promoting vaccination is need to addressed.


Textiles ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 55-85
Author(s):  
Tufail Hassan ◽  
Hafsa Jamshaid ◽  
Rajesh Mishra ◽  
Muhammad Qamar Khan ◽  
Michal Petru ◽  
...  

Recently, very rapid growth has been observed in the innovations and use of natural-fiber-based materials and composites for acoustic applications due to their environmentally friendly nature, low cost, and good acoustic absorption capability. However, there are still challenges for researchers to improve the mechanical and acoustic properties of natural fiber composites. In contrast, synthetic fiber-based composites have good mechanical properties and can be used in a wide range of structural and automotive applications. This review aims to provide a short overview of the different factors that affect the acoustic properties of natural-fiber-based materials and composites. The various factors that influence acoustic performance are fiber type, fineness, length, orientation, density, volume fraction in the composite, thickness, level of compression, and design. The details of various factors affecting the acoustic behavior of the fiber-based composites are described. Natural-fiber-based composites exhibit relatively good sound absorption capability due to their porous structure. Surface modification by alkali treatment can enhance the sound absorption performance. These materials can be used in buildings and interiors for efficient sound insulation.


Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1891
Author(s):  
Antonio Reina ◽  
Trung Dang-Bao ◽  
Itzel Guerrero-Ríos ◽  
Montserrat Gómez

Metal nanoparticles have been deeply studied in the last few decades due to their attractive physical and chemical properties, finding a wide range of applications in several fields. Among them, well-defined nano-structures can combine the main advantages of heterogeneous and homogenous catalysts. Especially, catalyzed multi-step processes for the production of added-value chemicals represent straightforward synthetic methodologies, including tandem and sequential reactions that avoid the purification of intermediate compounds. In particular, palladium- and copper-based nanocatalysts are often applied, becoming a current strategy in the sustainable synthesis of fine chemicals. The rational tailoring of nanosized materials involving both those immobilized on solid supports and liquid phases and their applications in organic synthesis are herein reviewed.


Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 266
Author(s):  
Shaked Eliyahu ◽  
Alexandra Galitsky ◽  
Esther Ritov ◽  
Havazelet Bianco-Peled

We developed and characterized a new hydrogel system based on the physical and chemical interactions of pectin partially modified with thiol groups and chitosan modified with acrylate end groups. Gelation occurred at high pectin thiol ratios, indicating that a low acrylated chitosan concentration in the hydrogel had a profound effect on the cross-linking. Turbidity, Fourier transform infrared spectroscopy, and free thiol determination analyses were performed to determine the relationships of the different bonds inside the gel. At low pH values below the pKa of chitosan, more electrostatic interactions were formed between opposite charges, but at high pH values, the Michael-type addition reaction between acrylate and thiol took place, creating harder hydrogels. Swelling experiments and Young’s modulus measurements were performed to study the structure and properties of the resultant hydrogels. The nanostructure was examined using small-angle X-ray scattering. The texture profile analysis showed a unique property of hydrogel adhesiveness. By implementing changes in the preparation procedure, we controlled the hydrogel properties. This hybrid hydrogel system can be a good candidate for a wide range of biomedical applications, such as a mucosal biomimetic surface for mucoadhesive testing.


Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1926
Author(s):  
Gaojie Li ◽  
Wenshuang Zhang ◽  
Na Luo ◽  
Zhenggang Xue ◽  
Qingmin Hu ◽  
...  

In recent years, bimetallic nanocrystals have attracted great interest from many researchers. Bimetallic nanocrystals are expected to exhibit improved physical and chemical properties due to the synergistic effect between the two metals, not just a combination of two monometallic properties. More importantly, the properties of bimetallic nanocrystals are significantly affected by their morphology, structure, and atomic arrangement. Reasonable regulation of these parameters of nanocrystals can effectively control their properties and enhance their practicality in a given application. This review summarizes some recent research progress in the controlled synthesis of shape, composition and structure, as well as some important applications of bimetallic nanocrystals. We first give a brief introduction to the development of bimetals, followed by the architectural diversity of bimetallic nanocrystals. The most commonly used and typical synthesis methods are also summarized, and the possible morphologies under different conditions are also discussed. Finally, we discuss the composition-dependent and shape-dependent properties of bimetals in terms of highlighting applications such as catalysis, energy conversion, gas sensing and bio-detection applications.


Sign in / Sign up

Export Citation Format

Share Document