scholarly journals Influence of heat treatment in the presence of certain metal ions on the spectral-fluorescent properties of an amylolytic enzyme preparation

2020 ◽  
Author(s):  
Н.Е. КУЛИКОВА ◽  
А.Г. ЧЕРНОБРОВИНА ◽  
Н.Н. РОЕВА ◽  
О.Ю. ПОПОВА
Keyword(s):  
Heat Treatment ◽  
Metal Ions ◽  
Conformational Changes ◽  
Fluorescence Spectra ◽  
Enzyme Preparation ◽  
Structural Changes ◽  
Enzyme Molecule ◽  
Fluorescent Properties ◽  
Amylolytic Enzyme ◽  
Enzyme Preparations

Тепловая обработка ферментных препаратов приводит к заметному изменению их активности в результате определенных конформационных изменений в молекуле фермента. На основе изучения ультрафиолетовых спектров авторы судят об изменении полярности окружения остатков триптофана при добавлении ионов цинка, алюминия и кальция. В работе приведены результаты изучения спектров флуоресценции ферментного препарата – ультраконцентрата глюкоамилазы Asp. awamori после тепловой обработки и добавления ионов некоторых металлов для обнаружения структурных изменений в молекуле фермента при этих воздействиях. Установлено, что совместное влияние ионов металлов и теплового воздействия на водный раствор ферментного препарата ультраконцентрата глюкоамилазы Asp. awamori приводит к повышению интенсивности свечения и смещению λmax в спектрах флуоресценции ультраконцентрата глюкоамилазы Asp. awamori в область более коротких длин волн. Это указывает на увеличение гидрофобности окружения триптофана и подтверждает конформационные изменения в молекуле фермента, происходящие под действием ионов некоторых металлов и при тепловом воздействии. The heat treatment of enzyme preparations leads to a noticeable change in their activity as a result of certain conformational changes in the enzyme molecule. On mastering the study of ultraviolet spectra, the authors judge a change in the polarity of the environment of tryptophan residues with the addition of zinc, aluminum and calcium ions. The paper presents the results of studying the fluorescence spectra of an enzyme preparation: glucoamylase ultraconcentrate Asp. awamori after heat treatment and the addition of certain ions of some metals to detect structural changes in the enzyme molecule under these influences. It was found that the combined effect of metal ions and thermal effects on the aqueous solution of the enzyme preparation of glucoamylase ultraconcentrate Asp. awamori, leads to an increase in luminescence intensity and a shift of λmax in the fluorescence spectra of Asp. awamori glucoamylase ultraconcentrate to the region of shorter wavelengths. This indicates an increase in the hydrophobicity of the tryptophan environment and provides confirmation of conformational changes in the enzyme molecule under the action of ions of certain metals and upon thermal exposure.

scholarly journals Optimization of water-heat treatment of barley batch (mix) in ethanol production

2020 ◽  
Vol 82 (3) ◽  
pp. 131-138
Author(s):  
G. V. Agafonov ◽  
T. S. Kovaleva ◽  
A. N. Yakovlev ◽  
A. S. Muravev ◽  
S. F. Yakovleva
Keyword(s):  
Heat Treatment ◽  
Mass Fraction ◽  
Enzyme Preparation ◽  
Raw Material ◽  
Multienzyme Complex ◽  
Viscosity Change ◽  
Enzyme Preparations ◽  
Treatment Stage ◽  
Optimal Mode ◽  
Object Of Study

Barley is a problematic raw material for ethanol processing due to its chemical composition. ?-glucans and pentosans high content increases the mass viscosity and digestible carbohydrates loss at еру water-heat treatment stage. The enzymes used to pre-treat grain prior to fermentation are traditionally ?-amylases and glucoamylases. The purpose of the work is to determine the optimal ratio of enzymes introduced in different periods of water-heat treatment. The object of study was barley: starch 52, protein 11.5, hemicellulose 5.1, ?-glucan 3.9, moisture 14.0. Enzyme preparations Alphaferm 3500L (0.5–1.0 AC / g starch), ViscoStar 150L (3700 units KS / cm3; 140 units ? – GcS / cm3; 1900 units CMC / cm3.), Prolive BS Liquid (600-750 units PS / cm?) were used in the work. The dynamics of viscosity change in the process of water-heat treatment was investigated in the work as well. It was found out that the dosage of the enzyme preparation Alphaferm 3500L has the greatest effect on the mass fraction of dry substances in the filtrate of barley mix, while the dosage of other enzyme preparations and the duration of the experiment have a smaller and similar effect. It was proved that the application of a multienzyme complex reduces the viscosity by 82% compared to the control. The method of indefinite Lagrange multipliers was used to determine the optimal mode of water-heat treatment. It was found out that the maximum accumulation of dry substances in the mixture is 16.4% and is achieved after 2.5 hours with the following doses of enzyme preparations: Alphaferm 3500 L - 0.6 units. AC / g starch; ViscoStar 150L - 0.025 units GCS / g starch; Prolyve BS Liquide 0.25 units PS / g starch.

Protein-induced conformational changes in 16S rRNA during assembly of the Escherichia Coli 30S ribosomal subunit: A STEM study

1987 ◽  
Vol 45 ◽  
pp. 910-911
Author(s):  
M. Boublik ◽  
V. Mandiyan ◽  
J.F. Hainfeld ◽  
J.S. Wall
Keyword(s):  
16S Rrna ◽  
Conformational Changes ◽  
Ribosomal Proteins ◽  
Structural Changes ◽  
Ribosomal Subunit ◽  
Compact Structure ◽  
E Coli ◽  
Freeze Dried ◽  
16S Rna ◽  
30S Subunit

The aim of this study is to understand the mechanism of 16S rRNA folding into the compact structure of the small 30S subunit of E. coli ribosome. The assembly of the 30S E. coli ribosomal subunit is a sequence of specific interactions of 16S rRNA with 21 ribosomal proteins (S1-S21). Using dedicated high resolution STEM we have monitored structural changes induced in 16S rRNA by the proteins S4, S8, S15 and S20 which are involved in the initial steps of 30S subunit assembly. S4 is the first protein to bind directly and stoichiometrically to 16S rRNA. Direct binding also occurs individually between 16S RNA and S8 and S15. However, binding of S20 requires the presence of S4 and S8. The RNA-protein complexes are prepared by the standard reconstitution procedure, dialyzed against 60 mM KCl, 2 mM Mg(OAc)2, 10 mM-Hepes-KOH pH 7.5 (Buffer A), freeze-dried and observed unstained in dark field at -160°.

Physical methods of research and monitoring

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 35-44
Author(s):  
S. G. Sandomirski
Keyword(s):  
Heat Treatment ◽  
Coercive Force ◽  
Remanent Magnetization ◽  
Structural Changes ◽  
Mechanical Load ◽  
Magnetic Hysteresis ◽  
Steel Structures ◽  
Magnetic Characteristics ◽  
Magnetic Parameters ◽  
Saturation Intensity

The main magnetic parameters sensitive to the structure of steels are the parameters of their saturation loop of magnetic hysteresis: the coercive force Hcs and remanent magnetization Mrs. The saturation magnetization or saturation intensity Mr is most sensitive to the phase composition of steels. The variety of steel grades and modes of technological treatment (e.g., heat treatment, mechanical load) determined the use of magnetic structurescopy and magnetic characteristics — the coercive force Hc, remanent magnetization Mr , and specific hysteresis losses Wh on the subloops of the magnetic hysteresis of steels — as control parameters in diagnostics of the stressed and structural states of steel structures and pipelines. It has been shown that changes in Hc, Mr , and Wh are more sensitive to structural stresses and structures of steels than the parameters of the saturation hysteresis loop of magnetic hysteresis (Hcs, Mrs, and Mrs). The formulas for calculating Hc, Mr and Wh are presented to be used for estimation of changes in the parameters upon heat treatment of steels. Features of the structural sensitivity of the subloop characteristics and expediency of their use for magnetic structural and phase analyzes are determined. Thus, the range of changes in Ìr attributed to the structural changes in steels upon gradual Hm decrease is many times wider compared to the range of possible changes in Mrs under the same conditions. Conditions (relations between the magnetic parameters) and recommendations regarding the choice of the field strength Hm are given which provide the justified use of Hc, Mr and Wh parameters in magnetic structurescopy

FERMENTATIVE HYDROLYTIC PREPARATION METHODS OF CEREAL WORT FOR ALCOHOL FERMENTATION

1970 ◽  
pp. 52-56
Author(s):  
Е. M. Serba ◽  
М. B. Overchenko ◽  
L. V. Rimareva ◽  
N. I. Ignatova ◽  
А. E. Orekhova ◽  
...  
Keyword(s):  
Alcoholic Fermentation ◽  
Raw Materials ◽  
Alcohol Concentration ◽  
Activity Level ◽  
Optimal Dosage ◽  
Main Role ◽  
Alcohol Fermentation ◽  
Ph Optimum ◽  
Amylolytic Enzyme ◽  
Enzyme Preparations

In the production of alcohol in the preparation of grain raw materials for fermentation, the main role is given to enzyme preparations of amylolytic action, which are key enzymes that catalyze the hydrolysis of starch. Amylolytic enzyme preparations with a different composition of enzymes and their level of activity, a mechanism of biocatalytic effect on starch, and a range of thermal and pH optimum are widely represented on the Russian market. The development of optimal conditions for the preparation of grain wort, the rational selection and dosage of concentrated enzyme preparations, the properties of which correspond to the parameters of the technological process, will ensure the effective preparation of starch for fermentation, and increase the profitability of alcohol production. The aim of this work was to study the influence of enzyme preparations of amylolytic action and the conditions of their use on the efficiency of the process of alcoholic fermentation and the yield of the final product, ethanol. The effect of various dosages of enzyme preparations of glucoamylase action, with a different ratio of the main enzyme glucoamylase and minor enzyme α-amylase, as well as methods for preparing wheat wort on the process of alcoholic fermentation, was studied. It was found that the enzyme preparation, the source of glucoamylase, in which α-amylase was present in a ratio of 15: 1 (in terms of activity level), turned out to be more effective in fermenting prepared wheat wort: its optimal dosage was 8 units. GLS / g starch. The presence of a sufficient amount of α-amylase in this preparation compensated for the dosage of thermostable α-amylase. The alcohol concentration in the mash was 10.2% vol., The alcohol yield was 67.9 cm3 / 100 g of starch. When glucoamylase with a lower ratio of the main and minor enzyme (75: 1) was used at the saccharification stage, an increase in the wort fermentation depth was observed with an increase in the concentration of glucoamylase to 9-10 units of GLS / g and α-amylase to 0.5 units. AC / g. It was also found that an increase in the duration of enzymatic-hydrolytic preparation of the wort had a positive effect on the fermentation process, the alcohol concentration in the mash increased to 10.2 vol.%. It was shown that the introduction of proteases into the wort helps to reduce the viscosity of grain wort, enriching it with assimilable yeast amino acids, which leads to an increase in the yield of alcohol. It has been confirmed that the synergy of the action of enzymes of amylolytic and proteolytic effects on polymers of grain raw materials allows to increase the efficiency of their conversion to ethanol. The conditions of enzymatic-hydrolytic processing of grain raw materials for fermentation are developed. The use of the digestion stage did not significantly affect the fermentation results of wheat wort.

Heat Treatment Influence on the Corrosion Resistance of a Cu-Al-Fe-Mn Bronze

2018 ◽  
Vol 69 (5) ◽  
pp. 1055-1059 ◽  
Author(s):  
Mariana Ciurdas ◽  
Ioana Arina Gherghescu ◽  
Sorin Ciuca ◽  
Alina Daniela Necsulescu ◽  
Cosmin Cotrut ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Structural Changes ◽  
Heating Temperature ◽  
Galvanic Corrosion ◽  
Cooling Water ◽  
Open Circuit ◽  
Water Quenching ◽  
Heat Treated ◽  
Different Temperatures

Aluminium bronzes are exhibiting good corrosion resistance in saline environments combined with high mechanical properties. Their corrosion resistance is obviously confered by the alloy chemical composition, but it can also be improved by heat treatment structural changes. In the present paper, five Cu-Al-Fe-Mn bronze samples were subjected to annealing heat treatments with furnace cooling, water quenching and water quenching followed by tempering at three different temperatures: 200, 400 and 550�C. The heating temperature on annealing and quenching was 900�C. The structure of the heat treated samples was studied by optical and scanning electron microscopy. Subsequently, the five samples were submitted to corrosion tests. The best resistance to galvanic corrosion was showed by the quenched sample, but it can be said that all samples are characterized by close values of open-circuit potentials and corrosion potentials. Concerning the susceptibility to other types of corrosion (selective leaching, pitting, crevice corrosion), the best corrosion resistant structure consists of a solid solution, g2 and k compounds, corresponding to the quenched and 550�C tempered sample.

Influence of Ascorbic Acid on the Structure and Function of Alpha-2- macroglobulin: Investigations using Spectroscopic and Thermodynamic Techniques

2020 ◽  
Vol 27 (3) ◽  
pp. 201-209
Author(s):  
Syed Saqib Ali ◽  
Mohammad Khalid Zia ◽  
Tooba Siddiqui ◽  
Haseeb Ahsan ◽  
Fahim Halim Khan
Keyword(s):  
Ascorbic Acid ◽  
Conformational Changes ◽  
Structural Changes ◽  
The Body ◽  
Titration Calorimetry ◽  
Spectroscopic Techniques ◽  
Human Beings ◽  
Plasma Ascorbic Acid ◽  
Dietary Antioxidant ◽  
And Function

Background: Ascorbic acid is a classic dietary antioxidant which plays an important role in the body of human beings. It is commonly found in various foods as well as taken as dietary supplement. Objective: The plasma ascorbic acid concentration may range from low, as in chronic or acute oxidative stress to high if delivered intravenously during cancer treatment. Sheep alpha-2- macroglobulin (α2M), a human α2M homologue is a large tetrameric glycoprotein of 630 kDa with antiproteinase activity, found in sheep’s blood. Methods: In the present study, the interaction of ascorbic acid with alpha-2-macroglobulin was explored in the presence of visible light by utilizing various spectroscopic techniques and isothermal titration calorimetry (ITC). Results: UV-vis and fluorescence spectroscopy suggests the formation of a complex between ascorbic acid and α2M apparent by increased absorbance and decreased fluorescence. Secondary structural changes in the α2M were investigated by CD and FT-IR spectroscopy. Our findings suggest the induction of subtle conformational changes in α2M induced by ascorbic acid. Thermodynamics signatures of ascorbic acid and α2M interaction indicate that the binding is an enthalpy-driven process. Conclusion: It is possible that ascorbic acid binds and compromises antiproteinase activity of α2M by inducing changes in the secondary structure of the protein.

Metastability in Monolayer Films Transferred onto Solid Substrates by the Langmuir-Blodgett Method: IR Evidence for Transfer-Induced Phase Transitions

1994 ◽  
Vol 48 (10) ◽  
pp. 1196-1203 ◽  
Author(s):  
Fazale R. Rana ◽  
Suci Widayati ◽  
Brian W. Gregory ◽  
Richard A. Dluhy
Keyword(s):  
Fatty Acid ◽  
Conformational Changes ◽  
Structural Changes ◽  
High Surface ◽  
Solid Substrate ◽  
Water Interface ◽  
Monolayer Films ◽  
Langmuir Blodgett ◽  
Monomolecular Film ◽  
Air Water Interface

The rate at which a monomolecular film is deposited onto a solid substrate in the Langmuir-Blodgett process of preparing supported monolayer films influences the final structure of the transferred film. Attenuated total reflectance infrared spectroscopic studies of monolayers transferred to germanium substrates show that the speed at which the substrate is drawn through the air/water interface influences the final conformation in the hydrocarbon chains of amphiphilic film molecules. This transfer-induced effect is especially evident when the monolayer is transferred from the expanded region of surface-pressure-molecular-area isotherms at low surface pressures; the effect is minimized when the film molecules are transferred from condensed phases at high surface pressures. This phenomenon has been observed for both a fatty acid and a phospholipid, which suggests that these conformational changes may occur in a variety of hydrocarbon amphiphiles transferred from the air/water interface. This conformational ordering may be due to a kinetically limited phase transition taking place in the meniscus formed between the solid substrate and aqueous subphase. In addition, the results obtained for both the phospholipid and fatty acid suggest that the structure of the amphiphile may help determine the extent and nature of the transfer-speed-induced structural changes taking place in the monomolecular film.

New insights into the structural basis of integrin activation

Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1155-1159 ◽  
Author(s):  
Jian-Ping Xiong ◽  
Thilo Stehle ◽  
Simon L. Goodman ◽  
M. Amin Arnaout
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Structural Basis ◽  
Integrin Activation ◽  
Cellular Functions ◽  
Electron Microscopic ◽  
The Past ◽  
Intracellular Signals ◽  
Bidirectional Signaling ◽  
New Hypothesis

Abstract Integrins are cell adhesion receptors that communicate biochemical and mechanical signals in a bidirectional manner across the plasma membrane and thus influence most cellular functions. Intracellular signals switch integrins into a ligand-competent state as a result of elicited conformational changes in the integrin ectodomain. Binding of extracellular ligands induces, in turn, structural changes that convey distinct signals to the cell interior. The structural basis of this bidirectional signaling has been the focus of intensive study for the past 3 decades. In this perspective, we develop a new hypothesis for integrin activation based on recent crystallographic, electron microscopic, and biochemical studies.

A phthalocyanine-based fluorescent sensor for Zn2+ ion

2013 ◽  
Vol 17 (01n02) ◽  
pp. 99-103 ◽  
Author(s):  
Hui He ◽  
Jian-Yong Liu ◽  
Dennis K.P. Ng
Keyword(s):  
Metal Ions ◽  
Spectral Properties ◽  
Fluorescence Spectra ◽  
Near Infrared ◽  
Fluorescent Sensor ◽  
High Sensitivity ◽  
Absorption And Fluorescence Spectra

This paper describes the preparation and spectral properties of a near-infrared fluorophore in which two bis(2-picolyl)amino moieties are axially linked to a silicon(IV) phthalocyanine core. The effects of various metal ions on its absorption and fluorescence spectra have been examined. The results indicate that this compound shows a high sensitivity and moderate selectivity toward Zn2+ ion.

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