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Tytuł:
Similarity between enzymatic and electrochemical oxidation of 2-hydroxyacridinone, the reference compound of antitumor imidazoacridinones.
Autorzy:
Mazerska, Zofia
Powiązania:
https://bibliotekanauki.pl/articles/1043630.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
peroxidase-mediated oxidation
antitumor acridinones
enzymatic activation
enzymatic and electrochemical transformations
Opis:
The present work is part of a wide research project aimed to elucidate the mechanism of the metabolic activation of the antitumor imidazoacridinone agent C-1311 selected for clinical trials. The objectives of the investigations presented here were: (i) to examine the enzymatic transformation of the reference compound 2-hydroxyacridinone and (ii) to test the similarity between enzymatic and electrochemical oxidation of acridinone compounds. This similarity was searched with respect to the usefulness of the electrochemical results for further studies on the metabolic oxidation of imidazoacridinone antitumor drugs. The enzymatic oxidation of 2-hydroxyacridinone was performed with a model system containing various amounts of horseradish peroxidase and hydrogen peroxide and was followed by UV-VIS spectroscopy and by HPLC. One product of the reaction was isolated and its chemical structure was identified. It was shown that 2-hydroxyacridinone was transformed by the studied system in a manner dependent on the amount of the enzyme and on the compound/H2O2 ratio. While under mild reaction conditions the transformation ran slowly to yield only one product, p1, independently of the reaction time, higher enzyme concentration resulted in several steps of transformation. Product p1 turned out to be a dimer: 1,1-bi(2-hydroxyacridinone). A comparison of the results of the enzymatic transformations of 2-hydroxyacridinone presented here with studies on the electrochemical oxidation reported earlier allowed us to show both transformations to be similar as far as the reaction pathway and two reaction products are concerned.
Źródło:
Acta Biochimica Polonica; 2003, 50, 2; 515-525
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of technological parameters on the course of acidic hydrolysis of starch
Wpływ parametrów technologicznych na przebieg kwasowej hydrolizy skrobi
Autorzy:
Kosicki, Z.
Jarosławski, L.
Zielonka, R.
Powiązania:
https://bibliotekanauki.pl/articles/1396399.pdf
Data publikacji:
1985
Wydawca:
Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
Tematy:
starch
enzymatic hydrolysis
pipe reactor
Opis:
The effect of technological parameters on the course of enzymatic hydrolysis of starch was investigated. The studies were performed in industrial c.onditions using a specially equipped continuous pipe reactor of a hydrolysate production capacity corresponding to the production of 50-70 t of syrup per day. The obtained results are presented graphically in the Figs.
Przeprowadzono badania wpływu parametrów technologicznych na przebieg procesu kwasowej hydrolizy skrobi. Badania hydrolizy skrobi prowadzono w warunkach przemysłowych, wykorzystując do tego celu specjalnie oprzyrządowany ciągły reaktor rurowy o zdolności produkcyjnej hydrolizatu odpowiadającej produkcji syropu 50-70-t/d. Pomiary stopnia scukrzenia przeprowadzono w obszarze zmian następujących parametrów technologicznych: - czasu reakcji (od 1 do 20 min), - temperatury reakcji (od 129 do 151 °C), - zakwaszenia (kwasem solnym) pH od 1,45 do 2,3 przy założonym stałym stężeniu mleczka krochmalowego ok. 38% s.s. Uzyskane dane przedstawiono na wykresach. Analiza krzywych pozwoliła dobrać optymalne parametry hydrolizy do produkcji poszczególnych gatunków syropów z uwzględnieniem ich jakości.
Źródło:
Acta Alimentaria Polonica; 1985, 11, 1; 89-95
0137-1495
Pojawia się w:
Acta Alimentaria Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxidative polymerization of lignins by laccase in water-acetone mixture
Autorzy:
Fiţigău, Ionița
Peter, Francisc
Boeriu, Carmen
Powiązania:
https://bibliotekanauki.pl/articles/1039496.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
lignin
organic solvent
laccase
enzymatic polymerization
Opis:
The enzymatic oxidative polymerization of five technical lignins with different molecular properties, i.e. Soda Grass/Wheat straw Lignin, Organosolv Hardwood Lignin, Soda Wheat straw Lignin, Alkali pretreated Wheat straw Lignin, and Kraft Softwood was studied. All lignins were previously fractionated by acetone/water 50:50 (v/v) and the laccase-catalyzed polymerization of the low molecular weight fractions (Mw < 4000 g/mol) was carried out in the same solvent system. Reactivity of lignin substrates in laccase-catalyzed reactions was determined by monitoring the oxygen consumption. The oxidation reactions in 50% acetone in water mixture proceed with high rate for all tested lignins. Polymerization products were analyzed by size exclusion chromatography, FT-IR, and 31P-NMR and evidence of important lignin modifications after incubation with laccase. Lignin polymers with higher molecular weight (Mw up to 17500 g/mol) were obtained. The obtained polymers have potential for applications in bioplastics, adhesives and as polymeric dispersants.
Źródło:
Acta Biochimica Polonica; 2013, 60, 4; 817-822
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of mineralization conditions on the effectiveness of enzymatic mineralization of hydrogels
Autorzy:
Pietryga, K.
Reczyńska, K.
Pamuła, E.
Powiązania:
https://bibliotekanauki.pl/articles/285814.pdf
Data publikacji:
2015
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
enzymatic mineralization
hydrogels
bone tissue engineering
Opis:
Polysaccharide hydrogels are widely used in food industry and medicine. Gellan gum (GG) recently gained a lot of attention as a promising material for tissue regeneration proposes due to its excellent biocompatibility and similarity to natural extracellular matrix. However, in unmineralized form it is not suitable for bone tissue engineering because of weak mechanical properties. Enzymatic mineralization (e.g. using alkaline phosphatase – ALP) is one of the methods of calcifying of hydrogels and it resembles natural processes occurring during bone healing. The aim of this research was to investigate mineralization of hydrogels and to improve properties of gellan gum scaffolds by adjusting processing conditions. Since ALP does not form with GG covalent bonds, during incubation in mineralization medium (solution of calcium glycerophosphate - CaGP) it is diffusing from the samples. Therefore, mineralization effectiveness depends on the interplay between incoming CaGP and outgoing ALP molecules. We hypothesize that better CaGP availability, especially in the first hours of incubation, can result in more effective and homogenous precipitation of calcium phosphates (CaP) in GG samples. To this end, samples with different GG and ALP concentration were subjected to two different mineralization regimes (more and less frequent CaGP exchanges). We proved that better CaGP availability (more frequent CaGP exchange) resulted in better mechanical properties (Young’s modulus) and more effective mineral formation (higher dry mass percentage) of the samples compared to the same samples mineralized with lower accessibility of CaGP. This may be related to the fact, that in presence of fresh organic substrates, more CaP are formed in the outer parts of the samples at the beginning of the process, that limit ALP diffusion and allow more uniform mineralization.
Źródło:
Engineering of Biomaterials; 2015, 18, 131; 2-7
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enzymatic assay of opioid analgesic, tramadol, using horseradish peroxidase
Autorzy:
Sridevi, N.
Srilakshmi, C.
Alekya, G.
Bala Sekaran, C.
Powiązania:
https://bibliotekanauki.pl/articles/10767.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
opioid
tramadol
horseradish peroxidase
enzymatic method
Opis:
Three novel and sensitive enzymatic methods have been developed for the quantification of tramadol in pharmaceutical dosage forms. The proposed methods are based on the reaction of tramadol with 3-methylbenzothiazoline-2-one hydrazone (method A), aniline (method B) and aminoantipyrine in the presence of hydrogen peroxide and horseradish peroxidase to give colored complexes. The colored complexes obtained with 3-methylbenzothiazoline-2-one hydrazone, aniline and aminoantipyrine exhibit absorption maxima at 480 nm, 550 nm and 530 nm, respectively. Regression analysis of Beer’s plots showed good correlation for tramadol in the concentration range (μg/mL) 2-12 for the methods A & B and 4-24 for the method C. The experimental parameters were studied and optimized. The precision and accuracy of the methods were satisfactory. The proposed methods were successfully applied for the quantification of tramadol in 3 brands of commercially available tablet dosage forms. The results were compared satisfactorily with the official method.
Źródło:
International Letters of Natural Sciences; 2014, 11, 1
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Change in hydrolytic enzyme efficiency over time
Autorzy:
Szadkowska, Dominika
Powiązania:
https://bibliotekanauki.pl/articles/2200102.pdf
Data publikacji:
2020
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
enzymatic hydrolysis
enzyme
poplar wood
holocellulose
Opis:
Change in hydrolytic enzyme efficiency over time. The purpose of this study was to determine the action of hydrolytic enzymes (by Dyadic Cellulase CP CONC, and the Dyadic Xylanase 2 XP CONC) over time. Chromatographic analysis of holocellulose samples subjected to enzymatic hydrolysis was performed. The following hydrolysis parameters were used: time 48h, temperature 45 ⁰C, acetate buffer pH 5.4, commercial enzymes Dyadic. Holocellulose extracted by the sodium chlorite method from white poplar wood (Populus alba L.) was used. The final yield of enzymatic hydrolysis was determined. The results of hydrolysis performed at intervals were compared. The results obtained show that the hydrolysis yield of holocellulose after five months decreased by 40 p.p. for glucose yield and by 25 p.p. for xylose yield. The yield for glucose after two and a half years decreases by 68 p.p. and 62 p.p. for xylose compared to the initial yield.
Zmiana wydajności enzymów hydrolitycznych w czasie Celem pracy było określenie działania enzymów hydrolitycznych w czasie. Przeprowadzono analizę chromatograficzną próbek holocelulozy poddanych hydrolizie enzymatycznej. Zastosowano następujące parametry hydrolizy: czas 48h, temperatura 45 ⁰C, bufor octanowy pH 5,4, enzymy komercyjne Dyadic. Zastosowano holocelulozę pozyskaną metodą chlorynu sodowego z drewna topoli bialej (Populs alba L.). Określono końcową wydajność hydrolizy enzymatycznej. Porównano wyniki hydrolizy przeprowadzonej w odstępach czasu. Uzyskane wyniki wskazują, że wydajność hydrolizy holocelulozy po pięciu miesiącach zmniejszyła się o 40 p.p. dla wydajności glukozy i o 25 p.p. dla wydajności ksylozy. Wydajność glukozy po dwóch i pół roku obniża się o 68 p.p., a ksylozy o 62 p.p. w stosunku do wydajności początkowej.
Źródło:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology; 2020, 112; 79--84
1898-5912
Pojawia się w:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New aspects of the enzymatic breakdown of chitin: a review
Autorzy:
Jankiewicz, Urszula
Kochańska-Jeziorska, Arletta
Gałązka, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/2129552.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Tematy:
chitinases
enzymatic degradation
lytic polysaccharide monooxygenases
Opis:
This review focuses on the enzymatic breakdown of chitin, taking into account the latest scientific reports on the activity of lytic polysaccharide monooxygenase (LPMO). Chitin is a natural, abundant polysaccharide of great practical importance in the environment. However, the insolubility in water and the tightly packed crystalline structure of chitin pose a serious obstacle to enzymatic degradation. This substrate can be converted into soluble sugars by the action of glycosidic hydrolases (GH), also known as chitinases. LPMO could prove to be helpful in enzymatic processes that increase the rate of chitin depolymerisation by improving the availability of substrates for chitinases. The unique action of LPMO is based on the ability to catalyse the oxidative cleavage of glycosidic chains present in complex, resistant crystal networks of chitin, and this cleavage facilitates the subsequent action of glycolytic hydrolases.
Źródło:
Progress on Chemistry and Application of Chitin and its Derivatives; 2021, 26; 5-10
1896-5644
Pojawia się w:
Progress on Chemistry and Application of Chitin and its Derivatives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of urea and formaldehyde on enzymatic hydrolysis of cellulose
Autorzy:
Marchwicka, Monika
Lesiak, Anna
Radomski, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/2200202.pdf
Data publikacji:
2020
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
enzymatic hydrolysis of cellulose
inhibitors
urea
formaldehyde
Opis:
Effect of selected urea and formaldehyde concentrations on glucose yield of enzymatic hydrolysis of cellulose was investigated. Urea and formaldehyde were added separately at the concentrations of 0.001, 0.002 and 0.005 g/cm3. Glucose was determined by high-performance liquid chromatography (HPLC). It was found that the used concentrations of urea didn’t influence glucose yield. In the case of formaldehyde, the results vary between used concentrations. The glucose yield of enzymatic hydrolysis of cellulose with the highest investigated concentration of formaldehyde (0.005 g/cm3) decreased by 50 %.
Wpływ mocznika i formaldehydu na hydrolizę enzymatyczną celulozy. Prezentowane badania miały na celu określenie wpływu wybranych dodatków mocznika i formaldehydu na wydajność glukozy w enzymatycznej hydrolizie celulozy. Mocznik oraz formaldehyd dodano osobno w stężeniach 0,001, 0,002 i 0,005 g/cm3. Wydajność glukozy po hydrolizie enzymatycznej oznaczano za pomocą wysokosprawnej chromatografii cieczowej (HPLC). Stwierdzono, że zastosowane stężenia mocznika nie miały wpływu na wydajność glukozy. W przypadku formaldehydu wyniki różnią się między zastosowanymi stężeniami. Wydajność glukozy hydrolizy enzymatycznej celulozy z największym badanym stężeniem formaldehydu (0,005 g/cm3) była prawie o połowę mniejsza w porównaniu do hydrolizy enzymatycznej celulozy bez formaldehydu.
Źródło:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology; 2020, 110; 92--96
1898-5912
Pojawia się w:
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degradability of polylactide films by commercial microbiological preparations for household composters
Autorzy:
Morawska, M.
Krasowska, K.
Powiązania:
https://bibliotekanauki.pl/articles/777966.pdf
Data publikacji:
2017
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
biodegradable polymers
polylactide (PLA)
enzymatic degradation
DSC
Opis:
Environmentally friendly polymers such as polylactide are increasingly becoming available for use in packaging applications. The main advantages of polylactide packaging are evident. Polylactide is based on renewable resources and can be degraded in compost or soil. The studies on degradability of polylactide (PLA) films by commercial preparation of mixture of multi-active saprophytic soil microorganisms, bacteria, actinomycetes and fungi have been done. Unmodified PLA film, metalized co-extruded PLA film and modified by silicon oxide PLA film were incubated in the liquid nutritious medium (TSB) prepared to support the growth of microorganisms. The degradability of polylactide films was examined by macro and microscopic observations of surface, changes of mass and crystallinity of polymer samples before and after incubation. The obtained results indicate that the degradation of polylactide was accelerated by the presence of a biological vaccine. It was found that PLA degradation in the inoculated TSB broth was a result of both: enzymatic and chemical hydrolysis.
Źródło:
Polish Journal of Chemical Technology; 2017, 19, 3; 44-48
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soil Redox Potential and its Impact on Microorganisms and Plants of Wetlands
Autorzy:
Tokarz, E.
Urban, D.
Powiązania:
https://bibliotekanauki.pl/articles/125438.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
redox potential
peatland
microbial communities
enzymatic activity
Opis:
Although peatlands cover only 3% of the Earth’s surface, they constitute a huge reservoir of carbon. It is estimated that they accumulate one third of carbon contained in all types of soils worldwide. Therefore, knowledge of the physical, chemical, and biological properties of peat is important for prevention of peat degradation and release of carbon stored as CO2 into the atmosphere. In organic soils, water plays a very important role as a protective factor against mineralisation of organic matter. Therefore, organic soils are characterised by high specificity and dissimilarity from mineral soils. The hydrological factor induces a variety of changes in the physical and chemical properties, e.g. low redox potential or low oxygen content in soil pores. Many soil processes are determined by the soil oxygenation status, which can be measured with various indicators as well as direct and indirect measurements. One of the indirect methods is measurement of the redox potential. The oxidation-reduction potential (redox potential or Eh) is a measure of the ratio of oxidised to reduced forms in a solution. This parameter is inextricably linked to oxygen supply and the processes of consumption thereof by microorganisms and plant roots. Therefore, the redox potential is used as an indicator of the oxygenation status and the content of biogenic forms and toxins in the soil environment and sediments. In the case of submerged soils, penetration of atmospheric oxygen into the soil is limited due to low rates of oxygen diffusion and, hence, low redox potential, which inhibits plant growth through inhibition of respiration and production of toxins in reducing conditions. The aim of this article is (1) to the show soil-plant-soil microorganism interactions taking place on peatbogs in the context of redox potential, (2) to investigate the responses of plants and soil microorganisms to the changing redox potential, and (3) to demonstrate the mechanisms of plant adaptation to the reducing conditions prevailing in peatbogs.
Źródło:
Journal of Ecological Engineering; 2015, 16, 3; 20-30
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of enzymatic effects on pit membranes using light and scanning electron microscopy
Autorzy:
Durmaz, S.
Yildiz, U.C.
Ozturk, M.
Serdar, B.
Powiązania:
https://bibliotekanauki.pl/articles/52338.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Drewna
Tematy:
investigation
enzymatic effect
pit membrane
light electron microscopy
scanning electron microscopy
spruce wood
permeability
enzymatic treatment
Źródło:
Drewno. Prace Naukowe. Doniesienia. Komunikaty; 2016, 59, 198
1644-3985
Pojawia się w:
Drewno. Prace Naukowe. Doniesienia. Komunikaty
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of cobalt ions on growth and enzymatic activity of entomopathogenic fungi used in biological plant protection
Autorzy:
Łopusiewicz, Ł.
Mazurkiewicz-Zapałowicz, K.
Tkaczuk, C.
Bartkowiak, A.
Powiązania:
https://bibliotekanauki.pl/articles/2084794.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cobalt
entomopathogenic fungi
enzymatic activity
heavy metals
Opis:
This study focused on the effect of heavy metal cobalt ions (at concentrations of 1–1000 ppm) on the development and enzymatic activity of four entomopathogenic fungi: Beauveria bassiana, Beauveria brongniartii, Isaria fumosorosea and Metarhizium robertsii, commonly used in biological plant protection. It was found that each of the tested species of fungi reacted individually to contact with the Co2+ ions at their various concentrations. Depending on the variants of the experiment carried out, there were changes in the development of the mycelia (mainly growth inhibition) and their morphological features (color and structure) in comparison to the control samples. Co2+ ions had a fungistatic effect on all fungal strains, whereas a fungicidal effect was noted at concentrations of 750 ppm and 1000 ppm against M. robertsii and I. fumosorosea, respectively. In addition, there was a discrepancy in enzymatic activity between the tested fungal species developing in the medium with varying concentrations of metal salt. The inhibitory effect of Co2+ ions on lipase production was observed in I. fumosorosea. Protease production was stimulated in B. bassiana at all Co2+ concentrations, whereas in M. robertsii this effect was noted at 1 ppm. The changing dynamics of extracellular fungal hydrolases, due to the action of Co2+ ions, may translate into the role of these microorganisms in the processes of insect pathogenesis. This work suggests that severe pollution of the environment by cobalt could be a restrictive factor for the development and pathogenicity of entomopathogenic fungi and must be taken into account for their successful application in biological plant protection.
Źródło:
Journal of Plant Protection Research; 2020, 60, 1; 58-67
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of wheat and Miscanthus straw biochars on soil enzymatic activity, ecotoxicity, and plant yield
Autorzy:
Mierzwa-Hersztek, Monika
Gondek, Krzysztof
Klimkowicz-Pawlas, Agnieszka
Baran, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/973069.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
biochar
soil
enzymatic activity
bioassays
crop yield
Opis:
The variety of technological conditions and raw materials from which biochar is produced is the reason why its soil application may have different effects on soil properties and plant growth. The aim of this study was to evaluate the effect of the addition of wheat straw and Miscanthus giganteus straw (5 t DM ha-1) and biochar obtained from this materials in doses of 2.25 and 5 t DM ha-1 on soil enzymatic activity, soil ecotoxicity, and plant yield (perennial grass mixture with red clover). The research was carried out under field conditions on soil with the granulometric composition of loamy sand. No significant effect of biochar amendment on soil enzymatic activity was observed. The biochar-amended soil was toxic to Vibrio fischeri and exhibited low toxicity to Heterocypris incongruens. Application of wheat straw biochar and M. giganteus straw biochar in a dose of 5 t DM ha-1 contributed to an increase in plant biomass production by 2 and 14%, respectively, compared to the soil with mineral fertilisation. Biochars had a more adverse effect on soil enzymatic activity and soil ecotoxicity to H. incongruens and V. fischeri than non-converted wheat straw and M. giganteus straw, but significantly increased the grass crop yield.
Źródło:
International Agrophysics; 2017, 31, 3
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resistance of mosses to drying, measured by the intensity of gas exchange and the content of malate and citrate
Autorzy:
Rzepka, Andrzej
Szarek, Wioleta
Powiązania:
https://bibliotekanauki.pl/articles/2173118.pdf
Data publikacji:
2021-11-20
Wydawca:
Uniwersytet Pedagogiczny im. Komisji Edukacji Narodowej w Krakowie
Tematy:
dehydration and rehydration
enzymatic activity
photosynthesis
respiration
Opis:
Desiccation tolerance, the ability to lose virtually all of its free intracellular water and then restore normal function when rehydrated, is one of the most remarkable features of bryophytes. The aim of the study was to determine the resistance of two species of Plagiomnium undulatum (Hedw.) T.J.Kop. and Polytrichum commune Hedw. on drying to 50% relative water content of the air and rehydration. Changes in the intensity of photosynthesis and respiration as well as the content of malate and citrate in leafy moss stems were analysed. P. commune gametophores showed greater resistance to drought stress than P. undulatum. In both species, photosynthesis was much more sensitive to drought than respiration. Changes in the content of malate and citrate indicated a high plasticity of moss metabolism in conditions of water shortage and may be one of many important elements of the adaptation strategy to water deficit. The reactions of the tested mosses to dehydration and rehydration confirmed their adaptation to specific land conditions.
Źródło:
Annales Universitatis Paedagogicae Cracoviensis Studia Naturae; 2021, 6; 109-124
2543-8832
2545-0999
Pojawia się w:
Annales Universitatis Paedagogicae Cracoviensis Studia Naturae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling studies of potato nucleoside triphosphate diphosphohydrolase NTPDase1: an insight into the catalytic mechanism
Autorzy:
Kozakiewicz, Anna
Neumann, Piotr
Banach, Mariusz
Komoszyński, Michał
Wojtczak, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/1040830.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
potato apyrase
NTPDase1
enzymatic mechanism
homology modeling
Opis:
Nucleoside triphosphate diphosphohydrolase - NTPDase1 (apyrase, EC 3.6.1.5) was modeled based on sequence homology. The single polypeptide chain of apyrase is folded into two domains. The putative catalytic site with the apyrase conserved regions (ACR 1-5) is located between these two domains. Modeling confirmed that apyrase belongs to the actin superfamily of proteins. The amino acids interacting with the nucleoside triphosphate substrate and probably involved in the catalyzed hydrolysis were identified. The proposed two-step catalytic mechanism of hydrolysis involves Thr127 and Thr55 as potential nucleophilic factors responsible for the cleavage of the Pγ and Pβ anhydride bonds, respectively. Their action seems to be assisted by Glu170 and Glu78 residues, respectively. The presence of two nucleophiles in the active site of apyrase explains the differences in the hydrolytic activity between apyrases and other enzymes belonging to the NTPDase family.
Źródło:
Acta Biochimica Polonica; 2008, 55, 1; 141-150
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł

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