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Aminokwasy, glikany, peptydy i białka w ścieżkach diagnostycznych i terapeutycznych chorób cywilizacyjnych XXI wieku : projektowanie i charakterystyka fizykochemiczna oraz strukturalna

Bylińska Irena, Dzierżyńska Maria, Giżyńska Małgorzata, Guzow Katarzyna, Jankowska Elżbieta, Jurczak Przemysław, Kaczyński Zbigniew, Karska Natalia, Kowalczyk Agnieszka, Kuncewicz Katarzyna, Orlikowska Marta, Sawicka Justyna, Spodzieja Marta, Szpakowska Nikola, Szymańska Aneta, Wieczerzak Ewa, Witkowska Julia, Rodziewicz-Motowidło Sylwia

Wiadomości Chemiczne

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2022

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[Z] 76, 5-6

393--431

EN

The civilization diseases of the 21st century are non-infectious disorders, affecting a large part of modern society. They are associated with the significant development of industry and technology, and hence with environmental pollution and an unhealthy lifestyle. These factors have led to the development of many civilization diseases, which currently include: cardiovascular diseases, respiratory diseases, diabetes, obesity, malignant tumors, gastrointestinal diseases, mental disorders and allergic diseases. The development of technologies, including modern therapies and new drugs, resulted in increase in life expectancy. This creates a global problem of an aging population with an increasing number of diseases of the old age, i.e. dementias. In addition, sedentary lifestyles and changing diets are the reasons why more and more people develop metabolic diseases, as well as neurological and cognitive disorders characterized by progressive damage to nerve cells and dementia. Currently, problem on a global scale is also the growing resistance to existing antimicrobial drugs. Therefore, the scientists face many challenges related to searching for the causes of these diseases, their diagnosis and treatment. Scientific research conducted at the Department of Biomedical Chemistry at the Faculty of Chemistry of the University of Gdańsk is part of this research trend. In this publication, we discuss various research topics with the long-term aim of solving the problems associated with the diseases mentioned above. The following chapters are dedicated to (i) looking for new effective fluorophores with diagnostic and anti-cancer activity; (ii) designing of new compounds with antibacterial and antiviral activity and their synthesis; (iii) investigating the mechanisms of amyloid deposit formation by human cystatin C and possibilities of inhibition of this process; (iv) designing and studies of compounds activating the proteasome with the potential to suppress the development of neurodegenerative diseases; (v) designing peptide fibrils and hydrogels as drug carriers; (vi) searching for peptide inhibitors of immune checkpoint as potential drugs for immunotherapy; (vii) studying the mechanism of action of selected herpesviruses by determining the structure of viral proteins and (viii) studying the composition of natural glycans and glycoconjugates in order to better understand the mechanisms of interaction of bacteria with the environment or with the host.

2

Changes in the fluorescence excitation and emissions spectra of heated and frying rapeseed oil and sunflower oil

Szukay Beata, Stachura Wojciech, Saletnik Łukasz, Budzyński Jacek, Szymańska Justyna, Fisz Jacek

Biotechnology and Food Science

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2019

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Vol. 83, nr 1

49--56

EN

Frying is a popular method of cooking (meals preparation). Heating and deep-fat frying cause a series of chemical reactions, such as oxidation of polyunsaturated fatty acids and vitamin E, as well as formation of trans isomers and products of peroxidation. These chemical reactions cause organoleptic and nutritional changes in the product, which may have a negative effect on health. For this reason, the usefulness of many methods for evaluation of refined oils quality is investigated. The fluorescence spectroscopy is increasingly used for this purpose. The aim of the study was to monitor the changes in emission and excitation spectra of refined rapeseed oil and sunflower oil after processes of heating and frying frozen French fries. The obtained results show the differences between the shapes of fluorescence excitation and emission spectra of both oils due to the two processes and these changes depend on duration of both processes. This study indicates that fluorescence spectroscopy is a promising method for evaluation of changes in oils during heating or frying.

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Badania FTIR-ATR i fluorescencyjne układów białkowo-lipidowych

Litwińczuk-Mammadova A., Cieślik-Boczula K., Rospenk M.

Wiadomości Chemiczne

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2017

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[Z] 71, 1-2

109--132

EN

Lipid-protein systems paly curtail roles in living systems [49]. Hence, a determination of their structure at different levels of organization is still one of the most important tasks in many research projects. A study of lipid-protein systems is based on many physicochemical techniques, such as spectroscopy of FTIR, Raman, fluorescence, NMR, EPR, as well as DLS, DSC and TEM methods. In the presented paper tow of the most frequently used methods, that is FTIR and fluorescence spectroscopy, will be discussed in details. They are characterized by a relatively low cost of sample preparation, a short measuring time, and they give a huge number of structural and physicochemical information about lipid-protein systems. In the FTIR-ATR spectroscopy many of vibrational bands are commonly used as very precise vibrational indicators of structural changes in lipids and proteins (Fig. 1) [1–6]. They allows to characterize lipid and protein components separately in mixed systems. Additionally, structural changes in lipid membranes can be monitored in one FTIR-ATR experiment simultaneously in a region of hydrophilic lipid head-groups (Fig. 5) [17, 18], in a hydrophobic part composed of hydrocarbon lipid chains (see Figures 2 and 3) [7–9], and in a lipid membrane interface represented by ester lipid groups (Fig. 4) [4, 6, 11, 12]. A secondary structure of proteins and peptides in different experimental conditions can be defined in the FTIR-ATR spectroscopy on the base of amide I bands (Fig. 6 and Tabs 1, 2 and 3) [20–22]. A fluorescence spectroscopy is a complementary methods to FTIR spectroscopy in a study of lipid-protein systems. It competes information about time-dependent and very fast (in a scale of femtoseconds) structural processes in both lipids [41–45] and proteins [23, 27, 48]. The folding, denaturation, and aggregation of proteins and lipid membranes accompanied by changes in an order, packing and hydration of the system under study [23, 27, 41–45, 48].

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Metody charakterystyki naturalnych organicznych składników wód ujmowanych z przeznaczeniem do spożycia przez ludzi

Machi J., Mołczan M.

Ochrona Środowiska

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2016

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Vol. 38, nr 4

25--32

PL

Wiedza o zawartości sumy naturalnych substancji organicznych nie jest obecnie wystarczająca zarówno przy planowaniu, jak i eksploatacji instalacji do oczyszczania wody. Pogłębiona charakterystyka zawartych w ujmowanych wodach naturalnych związków organicznych pozwala na lepsze zrozumienie ich przemian w procesach oczyszczania wody, a także odgrywa bardzo ważną rolę podczas optymalizacji pracy poszczególnych etapów układu technologicznego. Powszechnie stosowanym wskaźnikiem do analizy związków organicznych w wodzie jest absorbancja w nadfiolecie, która umożliwia zarówno ocenę jakościową, jak i ilościową tych związków. Absorbancja właściwa w UV (SUVA), jako odniesienie wartości absorbancji w 254 nm do zawartości w wodzie rozpuszczonego węgla organicznego, umożliwia natomiast kontrolę procesów oczyszczania wody, zwłaszcza w zakresie dawkowania koagulantów oraz utleniaczy. Inne metody charakterystyki naturalnych substancji organicznych stanowią domenę prac badawczych i nie są szerzej wykorzystywane w praktyce funkcjonowania przedsiębiorstw wodociągowych. Wśród nich na uwagę zasługują techniki spektroskopii fluorescencyjnej, które pozwalają na monitorowanie jakości wody w czasie rzeczywistym i cechują się zwiększoną selektywnością oraz czułością w zestawieniu z absorbancją w nadfiolecie. Analiza fluorescencyjna, umożliwiająca identyfikację frakcji biodegradowalnej związków organicznych, pozwala na wybór właściwych metod ich usuwania. Bardzo duże możliwości analityczne zapewnia chromatografia, zwłaszcza w połączeniu z szeroką gamą dostępnych detektorów. Umożliwia ona badanie takich cech substancji organicznych, jak masa cząsteczkowa, polarność, aromatyczność czy podatność na tworzenie ubocznych produktów dezynfekcji wody. Daje to szerokie możliwości interpretacyjne w odniesieniu do optymalizacji pracy układu technologicznego oczyszczania wody. Bardzo pomocne do charakteryzowania składu wody pod względem obecnych w niej związków organicznych są także metody frakcjonowania z wykorzystaniem membran lub żywic selektywnych. Separacja cząsteczek substancji organicznych według takich cech, jak wielkość, hydrofilowość czy kwasowość, pozwala na otrzymanie wyselekcjonowanych próbek, które mogą być poddane dalszym badaniom.

EN

Today’s knowledge on total Natural Organic Matter (NOM) content proves not sufficient both at planning and operation of water treatment installations. Detailed characteristics of NOM present in raw and treated water enables better understanding of its changes during water treatment processes as well as substantially contributes towards operation optimization of subsequent stages of a technological set-up. UV absorbance, a common indicator used for NOM analysis in water, allows for both its qualitative and quantitative assessment. Specific UV absorbance (SUVA), being the UV absorbance of a water sample at 254 nm normalized for dissolved organic carbon (DOC), allows monitoring of water treatment processes, especially in terms of coagulant and oxidizing agent dosing. Other NOM characterization methods are a domain for research and are not widely employed in daily practice of water supply corporations. Among those techniques, fluorescence spectroscopy methods are worth noticing as they enable water quality monitoring in real time and are characterized by higher selectivity and sensitivity compared to UV absorbance. Fluorescence analysis that allows identification of biodegradable organic fractions, enables selection of adequate methods of their removal. Chromatography offers a number of analytical capabilities, especially when combined with a wide range of available detectors. It allows examination of NOM characteristics such as molecular weight, polarity, aromaticity or susceptibility to water disinfection by-product formation. Thus multiple possibilities of interpretation arise in regard to optimization of technological system operation in water treatment. In terms of NOM presence, fractionation methods employing membranes and selective resins are particularly helpful in water composition characterization. NOM particle separation according to its size, hydrophilicity, acidity and others enables monitoring its removal susceptibility in particular treatment processes and predicting the technological effects based on NOM characteristics.

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Porównanie liniowych metod PCA (Principal Component Analysis) i LDA (Linear Discriminant Analysis) zastosowanych do klasyfikacji matryc wzbudzeniowo-emisyjnych wybranych grup substancji biologicznych

Leśkiewicz M., Kaliszewski M., Mierczyk Z., Włodarski M.

Biuletyn Wojskowej Akademii Technicznej

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2016

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Vol. 65, nr 1

15--31

PL

W pracy porównano właściwości dwóch liniowych metod (PCA i LDA) pozwalających na redukcję wymiarów w trakcie analizy cech oraz zbadano wydajność tych dwóch algorytmów w procesie klasyfikacji wybranego materiału biologicznego na podstawie jego wzbudzeniowo-emisyjnych matryc fluorescencyjnych. Stwierdzono, że metoda LDA redukuje liczbę wymiarów (znaczących zmiennych) bardziej efektywnie niż metoda PCA. Za pomocą algorytmu LDA udało się uzyskać względnie dobre rozróżnienie badanego materiału biologicznego.

EN

Quality of two linear methods (PCA and LDA) applied to reduce dimensionality of feature analysis is compared and efficiency of their algorithms in classification of the selected biological materials according to their excitation-emission fluorescence matrices is examined. It has been found that LDA method reduces the dimensions (or a number of significant variables) more effectively than PCA method. Arelatively good discrimination within the examined biological material has been obtained with the use of LDA algorithm.

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Sectrofluorometric characterisation of the lubricate oil

Baszanowska E., Otremba Z.

Journal of Polish CIMAC

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2014

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Vol. 9, no 2

17--22

EN

Exploitive features of lubricate oils are externalised by various physical and chemical parameters (for example temperature dependencies of density and viscosity, ignition point or water content). On the other hand it is well-known that fluorescence spectra of various types of crude oils and their derivatives are strongly differ from each other. It is reasonable thesis, that exploitive features of oil may be related to transformations of light inside the oil. Therefore, despite of that fact light transformations strongly depend on chemical composition of oil (especially from the content of cyclic and polycyclic molecules). No one can exclude, that physical conditions are for fluorescence processes closely related to changes of physical and chemical properties of oil (and consequently to exploitive features) as well as to newly arising compounds and intrusions (for example metals, caused by contact with various engine elements). The paper presents spectra of fluorescence of exemplary lubricate oil (Marinol) in various configurations, namely: emission spectrum for individual excitation wavelength, excitation spectrum for single emission wavelength, excitation-emission spectrum, synchronous fluorescence spectroscopy and total synchronous fluorescence spectroscopy. Dynamic structures of those spectra gives reason to conclude that shapes of fluorescence spectra may be controlled by exploitive features of oils.

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Analiza struktury substancji humusowych gleb po wprowadzeniu węgla brunatnego na podstawie widm fluorescencyjnych

Kwiatkowska-Malina J.

Inżynieria i Ochrona Środowiska

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2011

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T. 14, nr 3

197-208

PL

Badania dotyczyły analizy właściwości substancji humusowych (SH) oraz kształtowania struktury kwasów huminowych (KH) gleb po wprowadzeniu preparatu wytworzonego na bazie (85%) odpadowego węgla brunatnego. Do badań wykorzystano materiał glebowy z wieloletnich statycznych doświadczeń polowych i mikropoletkowych, a jako źródło materii organicznej Rekulter preparat wyprodukowany na bazie węgla brunatnego odpadowego i węgla brunatnego typu ziemistego z Zagłębia Konińskiego (KWB Konin). Niższe wartości intensywności fluorescencji na widmach 3-D EEM dla KH z gleby rdzawej (piaszczystej) wskazują na większy wpływ materii organicznej z węgla brunatnego na gleby bardzo lekkie piaszczyste w porównaniu do gleb cięższych (brunatna kwaśna, płowa). Wyniki ponad 20-letnich doświadczeń polowych na glebie rdzawej potwierdziły korzystne, długotrwałe oddziaływanie węgla brunatnego na właściwości gleby oraz na stan materii organicznej z tego źródła.

EN

Soil is non-renewable and a very complex natural resource which performs many vital functions: food (99%) and other biomass production, storage, filtration and transformation of many substances including water, carbon, nitrogen. Soil as a top layer of the earth's crust is the first receiver of anthropogenic contaminants, and may or may not serve as a natural barrier to protect groundwater against contamination from the surface. One of the most important indicators of soil quality is soil organic matter (SOM), which is an important building block for the soil structure, formation of stable aggregates, and is able to improve the infiltration rates and the storage capacity of water. SOM presents a major pool carbon in the biosphere and can act both as a source and sink for carbon dioxide and other greenhouse gases. Agricultural intensification and cultivation in general results in a serious decrease in SOM as compared to that in the natural vegetation. Presently, the protection of SOM is one of the main tasks in EU, because SOM in addition to its soil fertilizing function can act in the elimination of the soil contamination and carbon sequestration. In this context, humic substances (especially humic and fulvic acids) and cohesive fractions (clay, silt, silt clay, etc.) present in soil are favourable components. It is because of their high sorption capacity with respect to many contaminants, including heavy metals, which may results in their immobilisation and, consequently protect groundwater against contamination. Antropogenically transformed soils often do not contain humic substances (HS), thus their role as a natural barrier is decreased. Therefore, re-generation of HS through humification of organic matter from diverse sources added to soils, may be the way to re-built the protective character of soil barrier, and consequently to reduce environmental and/or health risks at areas under anthropopression. Transformation processes of brown coal applied to soil were described to evaluate the use of this material as an effective source of organic matter and HS generation in degraded soils. The goal of this study was to discuss fine brown coal derived preparation as effective sources of organic matter (and humic substances) especially in soils that are anthropogenically transformed. The research concerned the analysis of properties of HS as well as formations of humic acids (HAs) in soils after addition brown coal. Soil materials used in the research was collected from the long term field experiments and microplots, as the source of organic matter the Rekulter that is based (85%) on brown coal (soft smudge type) obtained from the Konin Basin deposits preparation was used. For qualitative characteristic of SOM, particularly, in HAs, modern analytical technique such as fluorescence intensity (FI) for 3-D EEM spectra was used. The lowest fluorescence intensity (FI) for 3-D EEM spectra were observed in the case of HAs extracted from rusty soil. The 20-years research results carried out on rusty soil (sandy) confirmed long-term effect of brown coal on soil properties as well as on organic matter that originated from this source.

8

Concentrations of PM2.5, PM2.5-10 and PM-related elements at two heights in an urban background area in Zabrze (Poland)

Rogula-Kozłowska W., Błaszczak B., Klejnowski K.

Archives of Environmental Protection

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2011

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Vol. 37, no. 2

31-47

EN

Concentrations and elemental composition of fine (PM2.5) and coarse (PM2.5-10) ambient particles, at two sampling points located at the same urban background sites, were investigated. The points were 20 m distant from each other and at various heights (2 and 6 m) above the ground. A dichotomous sampler, equipped with a virtual impactor, and a cascade impactor were used to sample the dust. An X-ray fluorescence spectrometer was used in the elemental analyses. The investigations revealed heterogeneity of the spatial distribution and the elemental composition of suspended dust at the investigated urban background site. Coarse dust, whose concentration at 2.0 m above the ground was affected by secondary emission from roads, soil and other local low-level sources in some periods, appeared more heterogeneous.

PL

Celem pracy było zbadanie stężeń i składu pierwiastkowego pyłu drobnego (PM2,5) i grubego (PM2,5-10) w dwóch punktach wybranych w obszarze tła miejskiego w Zabrzu. Punkty były w zlokalizowane w odległości 20 m od siebie na różnych wysokościach (2 i 6 m). Do pobierania próbek pyłu wykorzystano dwukanałowy pobornik z impaktorem wirtualnym i impaktor kaskadowy. Badania składu pierwiastkowego przeprowadzono wykorzystując spektrometr fluorescencji rentgenowskiej. Badania wykazały heterogeniczność w rozkładzie przestrzennym i składzie pierwiastkowym pyłu zawieszonego w punkcie tła miejskiego. Wniosek ten dotyczy przede wszystkim frakcji cząstek grubych, których, jak wykazano w pracy, imisję w pewnych okresach, na wysokości 2 m, kształtuje wtórna emisja pyłu drogowego, glebowego i inne lokalne "niskopoziomowe" źródła pyłu.

9

Application of ion chromatography and energy dispersive x-ray fluorescence spectrometry for examination of chemical composition of mineral fertilizers

Michalski R., Łyko A., Szopa S.

Archives of Environmental Protection

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2011

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Vol. 37, no. 2

93-107

EN

Product quality tests require accurate and precise analytical techniques. Fertilizers belong to a group of products whose chemical composition is of great importance due to health, environmental and economic reasons. The following paper presents the results of the research into the content of selected substances in several mineral fertilizers manufactured in Poland. Ion chromatography (IC) was employed to determine selected inorganic anions and cations, whereas energy dispersive X-ray fluorescence spectrometry (EDXRF) was used to determine the content of selected elements.

PL

Badania jakości produktów wymagają stosowania dokładnych i precyzyjnych technik analitycznych. Do produktów, których skład chemiczny ma ogromne znaczenie zarówno ze względów zdrowotnych, ekologicznych, jak i ekonomicznych, należą nawozy mineralne. W pracy przedstawiono wyniki badań zawartości wybranych substancji w kilkunastu nawozach mineralnych produkowanych w Polsce. Do oznaczania wybranych nieorganicznych anionów i kationów wykorzystano technikę chromatografii jonowej (IC), a do badania zawartości wybranych pierwiastków technikę spektrometrii fluorescencji rentgenowskiej z dyspersją energii (EDXRF).

10

Zjawisko generowania fal harmonicznych oraz jego wykorzystanie praktyczne ze szczególnym uwzględnieniem współczesnej ultrasonografii

Jeka S., Sokólska E., Dura M., Żuchowski P.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2011

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Vol. 17, nr 2

140-143

PL

Od wielu lat z postępem w dziedzinie fizyki związany jest postęp w naukach przyrodniczych. Jednym ze zjawisk, które odgrywa coraz większą rolę w naukach przyrodniczych, jest zjawisko generacji drugiej harmonicznej w ośrodkach anizotropowych. Możliwość uzyskania fali o podwojonej częstotliwości w stosunku do fali podstawowej pozwoliło na prowadzenie badań, wcześniej trudnych bądź niemożliwych do przeprowadzenia. Dzięki wyższej jakości obrazu badania ultrasonograficzne stały się bardziej czułe i są powszechnie wykorzystywane, m.in. w kardiologii, radiologii, chirurgii, reumatologii czy diagnostyce onkologicznej. Ultrasonografia staje się niezwykle cenioną metodą obrazowania obok rezonansu magnetycznego czy tomografii komputerowej. Ze względu na jej dostępność wiązane są z nią duże nadzieje na przyszłość.

EN

The progress in physics results in life sciences advancement. One of the phenomena, which plays more and more important role in life sciences, is the second harmonic generation in anisotropic materials. The possibility of achieving the wave, characterized by double frequency – with relation to the initial wave, allowed to conduct examinations, which were previously very difficult or impossible to perform. Thanks to higher quality of image, ultrasound examination has become more sensitive and is widely used, even in cardiology, radiology, surgery, rheumatology and oncology diagnostics. Ultrasonography with the use of tissue harmonic imaging is very valued method, so as magnetic resonance imaging or CT scan and due to its availability, high expectations are associated with it for the future.

11

Study of interaction between humic acids and fullerene C60 using fluorescence quenching approach

Klavins M., Ansone L.

Ecological Chemistry and Engineering. S

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2010

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Vol. 17, nr 3

351-362

EN

The interaction between buckminsterfullerene C60 and humic acids (HA) of different origins was compared using fluorescence spectroscopy as a function of pH, humic acid concentration, ionic strength. Binding constants between fullerene and humic acids were calculated. It can be suggested that the complexation was driven by hydrophobic interactions depending on the properties of the interacting compounds. Hydrophobic interaction model as indicated by linear Stern-Volmer plots and high Kd values is characterizing the interaction between buckminsterfullerene C60 and humic acids The results of this study support the development of understanding of the fate of nanomaterials in the environment as well as the development of analytical methods for nanomaterials in waters and wastewater treatment approaches.

PL

Porównywano oddziaływania między buckminsterfulerenami C60 i kwasami huminowymi (HA) różnego pochodzenia w zależności od pH, stęzenia kwasów huminowych i siły jonowej. Do badań stosowano spektroskopię fluorescencyjną. Obliczono stałe trwałości związków kwasów huminowymi i fulerenów. Można przypuszczać, że kompleksowanie jest powodowane oddziaływaniami hydrofobowmi, zależnymi od właściwości związków. Model interakcji hydrofobowych wskazanych przez liniowe zależności Sterna-Volmera i duże wartości Kd charakteryzują interakcje między buckminsterfulerenami C60 i kwasami huminowymi. Wyniki opisanych badań są ważne dla poznania losu nanomateriałów w środowisku, a także dla rozwoju metod analizy zawartości nanomateriałów w wodach oraz metod oczyszczania ścieków.

12

Aktywność katalityczna pojedynczych cząsteczek enzymów

Jakubaszek J., Molski A.

Wiadomości Chemiczne

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2008

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[Z] 62, 7-8

635-658

EN

As early as in 1961, it has been demonstrated that turnovers of individual enzyme molecules can be detected [1]. In the nineties, advances in single-molecule methods, in particular in confocal microscopy (Fig. 1), made it possible to monitor more closely enzymatic turnovers at a single-molecule level [2-5]. This led to the discoveries of static disorder and dynamic disorder, and closely related memory effects in enzymatic turnovers [6-8]. Differences in activity of individual molecules of the same enzyme are called static disorder. Time-dependent fluctuations of enzymatic activity are called dynamic disorder. One manifestation of dynamic disorder is the fact that consecutive enzymatic turnovers are not statistically independent, which is called "memory effect". It is believed that static dis-order and dynamic disorder are related to conformational dynamics of enzyme molecules. In this review we discuss current issues of single-molecule enzymology, in particular kinetic effects that are specific to single-enzyme measurements. First we review the conceptual basis of single-enzyme kinetics and the initial work on single enzymes. We focus on the ping-pong mechanism of bisubstrate enzyme reactions (Eqs. (1) and (2)), and consider fluorescence trajectories (Figs. 2 and 3) associated with enzymatic turnovers. Two cases are distinguished. In the first, fluorescence comes from an enzyme molecule and fluorescence intensity jumps called blinking carry information on enzymatic activity. Jumps between a fluorescent (on) and non-fluorescent (off) states (Eqs. (4), (5), and Fig. 2) indicate the moments when the photophysical state of an enzyme changes during enzymatic turnovers. In the second case, fluorescence comes from product molecules whereas enzyme and substrate are non-fluorescent. Fluorescence bursts on a trajectory indicate the moments when non-fluorescent substrate molecules are converted into fluorescent product molecules that subsequently diffuse away from the detection volume (Eqs. (8), (9) and Fig. 3). In Section 1 we present selected experiments implying the effect of conformational dynamics on enzymatic kinetics. In Section 1.1, we discuss cholesterol oxydase and dihydroorotate dihydrogenase as examples of enzymes whose on-off fluorescence blinking is caused by chemical reactions at the enzyme active site. In Section 1.2 we discuss ?-lactosidase and lipase B as enzymes which turnovers can generate fluorescent products from suitably chosen non-fluorescent substrates. In Section 2, we review modeling and simulations of single-enzyme data. The aim of data modeling is to gain insight into single-enzyme activity through analysis of models of increasing complexity. Phenomenological models attempt to capture the essence of single-enzyme kinetics without going into molecular details. If a model is simple enough it may allow analytical solutions. For instance, a simple model of on-off blinking is given in Scheme (25). This scheme is capable of reproducing memory effect that can be visualized by a two-dimensional histogram of consecutive on and off times (Figs. 5a and 5b). Finally, in the last section we present an outlook for single-molecule enzymology.

13

Historia atomowej analizy spektralnej. Cz. III. Rozwój analizy ilościowej

Godlewska-Żyłkiewicz B.

Analityka : nauka i praktyka

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2007

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nr 4

36-38