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Hemoglobin and allostery
No full textHemoglobin je kompleksni protein prisutan u crvenim krvnim stanicama i igra ključnu ulogu u transportu kisika i ugljikovog dioksida u organizmu. Sastoji se od četiri podjedinice (dvije alfa i dvije beta podjedinice - α2β2), pri čemu svaka podjedinica sadrži mjesto za vezanje kisika, omogućujući učinkovit prijenos kisika iz pluća do tkiva i organa. Alosterija, važan biokemijski koncept, opisuje promjene u strukturi proteina koje utječu na njegovu funkciju. Kod hemoglobina, alosteričke promjene mijenjaju sposobnost hemoglobina za vezivanje i otpuštanje kisika. To znači da hemoglobin može prilagoditi svoju aktivnost ovisno o uvjetima u okolišu, kao što su pH i koncentracija CO2. Jedan od najpoznatijih primjera alosterije u hemoglobinu je Bohr efekt, gdje promjene u pHvrijednosti okoline utječu na afinitet hemoglobina za kisik. Ovaj mehanizam omogućava hemoglobinu da isporučuje kisik gdje je najpotrebniji u tijelu. Osim toga, hemoglobin može biti moduliran egzogenim faktorima poput organskih fosfata i 2,3-bisfosfoglicerata (BPG).Hemoglobin is a complex protein present in red blood cells and plays a key role in the transportation of oxygen and carbon dioxide in the body. It consists of four subunits (two alpha and two beta subunits - α2β2), with each subunit containing a binding site for oxygen, enabling efficient transfer of oxygen from the lungs to the tissues and organs. Allosterism, an important biochemical concept, describes changes in the protein's structure that affect its function. In the case of hemoglobin, allosteric changes alter its ability to bind and release oxygen. This means that hemoglobin can adjust its activity depending on environmental conditions, such as pH and CO2 concentration. One of the most well-known examples of allosterism in hemoglobin is the Bohr effect, where changes in the pH of the environment influence hemoglobin's affinity for oxygen. This mechanism allows hemoglobin to deliver oxygen where it is most needed in the body. Additionally, hemoglobin can be modulated by exogenous factors such as organic phosphates and 2,3-bisphosphoglycerate (BPG)
Characterization of the new potentiometric sensor for determination of promethazine
No full textPrometazin hidroklorid (PM) je derivat fenotiazina sa snažnim antihistaminskim i sedativno-hipnotičkim učinkom. Također ima antiemetičko, antikolinergičko i lokalno anestetičko djelovanje. Prekomjerna upotreba lijeka može uzrokovati ozbiljne nuspojave kao što su gubitak koordinacije, pospanost, nesvjestica, proširene zjenice, teško disanje itd. Stoga je određivanje PM u farmaceutskim pripravcima i biološkim uzorcima iznimno značajan predmet znanstvenih istraživanja. Cilj ovog rada je karakterizacija novorazvijenog senzora s tekućom membranom za potenciometrijsko određivanje PM. Za pripravu tekuće membrane senzora, PM-tetrafenilboratni (PM-TPB) kompleks korišten je kao senzorski materijal. Tekuća membrana novorazvijenog PM-TPB senzora sadržava: 1 % senzorskog materijala, 33 % poli(vinil-klorida) (PVC) i 66 % o-nitrofenil oktil etera kao plastifikatora. Razvijeni senzor ima nagib kalibracijske krivulje od 56,2 mV/dekada aktiviteta, nisku granicu detekcije od 1,25∙10-7 mol/dm3 u širokom mjernom području od 6,17∙10-7 do 5,0∙10-3 mol/dm3. Tijek signala novorazvijenog PM-TPB senzora iznosio je -2,5 mV/h. Senzor se može koristiti u pH rasponu od 2 do 8, u razdoblju od oko 4 tjedna i ima brzo vrijeme odziva od oko 10 s. Potenciometrijski koeficijenti selektivnosti izračunati metodom stalne koncentracije smetajuće tvari (interferenta) pokazuju da senzor ima dobru selektivnost.Promethazine hydrochloride (PM) is a phenothiazine derivative with potent antihistaminic and sedative-hypnotic effects. It also has antiemetic, anticholinergic effects and local anaesthetic actions. The excessive use of drug may cause serious side effects such as loss of coordination, sever drowsiness, fainting, dilated pupils, weak breathing etc. Thus, the determination of drug is subject of great scientific importance especially in pharmaceutical and biological samples. The aim of this work is the characterization of the new liquid membrane sensor for potentiometric determination of PM. For the preparation of the sensor liquid membrane, PM-tetraphenylborate (PM-TPB) complex was used as sensing material. The liquid membrane of the new PM-TPB sensor contained: 1% of sensing material, 33% of polyvinyl chloride (PVC) and 66% of o-nitrophenyl octyl ether as a plasticizer. The developed sensor has a slope of 56.2 mV/decade of activity, a low detection limit of 1.25∙10-7 mol/dm3 in wide measurement range from 6.17∙10-7 to 5.0∙10-3 mol/dm3. Signal drift of the new PM-TPB sensor was -2,5 mV/h. The sensor can be used in a pH range of 2 - 8, for a period of approximately 4 weeks and has fast response time of approximately 10 s. The potentiometric selectivity coefficients calculated using fixed interference method indicates that the sensor has good selectivity
Botulinum toxin and botulisam
No full textIstraživanje o toksinima obuhvaća veliko područje toksikologije. Toksin botulin može rasti samo u uvjetima bez kisika, a proizvodi ga anaerobna bakterija Clostridium botulinum. Do pojave trovanja imenovanim toksinom dolazi uslijed konzumacije hrane u kojoj je prisutna toksična bakterija, ali se ona može unijeti u organizam i putem otvorenih, medicinski neadekvatno preveniranih rana. U ovom završnom radu opisan je botulin, najjači prirodni neurotoksin, čija je masa od nekoliko stotina grama dostatna za ubojstvo cijelog čovječanstva. Botulin je protein koji se veže na živčane stanice i blokira lučenje neurotransmitera acetilkolina. Posljedično dolazi do blokade prijenosa živčanog podražaja na mišiće i paralize mišića. Botulin je danas našao svoje mjesto u svijetu estetike te je od otrova koji sa sobom nosi smrt zbog respiratorne paralize postao simbolom estetskih zahvata.Research on toxins encompasses the large field of toxicology. Botulinum toxin can only grow in conditions without oxygen, and it is produced by the anaerobic bacteria Clostridium botulinum. Poisoning with this toxin occurs due to the consumption of food containing toxic bacteria, but it can also enter the body through open, medically inadequately prevented wounds. This final paper describes botulinum, the strongest natural neurotoxin, which several hundred grams is sufficient to kill the entire humanity. Botulinum is a protein that binds to nerve cells and blocks the secretion of the neurotransmitter acetylcholine. As a result, nerve impulse transmission to the muscles is blocked, and muscle paralysis occurs. Today, botulinum has found its place in the world of aesthetics, and from being a toxin that brings death due to respiratory paralysis, it has become a symbol of aesthetic procedures
Study of the application of the fresh stone fruit as alternative pH indicator
No full textOpće prihvaćen pojam "koštičavo voće" obuhvaća širok raspon voća koje se uzgaja diljem svijeta. Ovaj naziv se odnosi na voće čiji plod ima tvrdu košticu u sredini. Najpoznatiji primjerci uključuju šljive, breskve, trešnje, višnje, i tako dalje. Mnoge vrste koštičavog voća sadrže pigmente koji mijenjaju boju otopine ovisno o pH vrijednosti. Stoga se takav biljni materijal može koristiti kao alternativni prirodni kiselo-bazni indikator. Cilj ovog rada bio je ispitati mogu li svježi plodovi koštičavog voća poslužiti kao prirodni kiselo-bazni indikator. Korišteno je nekoliko vrsta svježeg voća, konkretno višnje, trešnje, šljive, breskve, marelice, nektarine, ringlov, japanske trešnje i drenjine. Za pripremu indikatora korištena su otapala voda, aceton, etanol i metanol. Preliminarna ispitivanja provedena su na višnjama i drenjinama kako bi se odabrala otapala i odredio optimalni omjer biljnog materijala i otapala. Rezultati su pokazali da se svježe koštičavo voće, posebno šljive, višnje i trešnje, može uspješno koristiti kao prirodni kiselo-bazni indikator.The generally accepted term "stone fruit" covers a wide range of fruit grown around the world. This name refers to a fruit that has a hard stone in the middle. The most common examples include plums, peach, cherries, sour cherries, etc. Many types of stone fruit contain pigments that change the colour of the solution depending on the pH value. Therefore, such plant material can be used as an alternative natural acid-base indicator. The aim of this work was to examine whether selected fresh stone fruit can serve as a natural acid-base indicator. Several types of fresh fruit were used, e.g. sour and sweet cherries, plums, peach, apricots, nectarines, cherry plums, Japanese cherries and Cornelian cherries. Water, acetone, ethanol and methanol were used to prepare the indicator. Preliminary tests were carried out on sour cherries and Cornelian cherries in order to select solvents and to determine the optimal plant material / solvent ratio. The results showed that fresh stone fruit, especially plums, sour cherries and sweet cherries, can be successfully used as a natural acid-base indicator
Methods of determining of salicylic acid
No full textSalicilna kiselina je prirodni metabolit u biljkama, i njezinom modifikacijom mogu se dobiti njezini derivati, salicilati, koji se najčešće koriste u medicinske svrhe. Najpoznatiji predstavnik salicilata je acetilsalicilna kiselina, odnosno aspirin. Kao i mnogi derivati salicilne kiseline i acetilsalicilna kiselina sadrži protuupalna svojstva te je široko rasprostranjena. Izolacija salicilne kiseline započela je još u 19. st. kada se smatralo kako kora vrbe ima protuupalna djelovanja. Tijekom godina porasla je popularnost salicilne kiseline zbog njezinih raznih primjena te su se krenule razvijati metode za njezino određivanje te za određivanje salicilata. Zbog povećane popularnosti salicilne kiseline povećala se i konzumacija, čime raste potreba za određivanje njezine koncentracije u okolišu, vodama i proizvodima. U ovom radu obrađeno je pet najkorištenijih metoda kojima se može odrediti prisutnost salicilne kiseline i njezinih derivata. Najkorištenije metode su: kolorimetrija, spektofluorimetrija, tekućinska kromatografija visoke razlučivosti obrnutih faza, potenciometrija i voltametrija.Salicylic acid is a natural metabolite in plants, and its modifications can be used to obtain its derivatives, salicylates, which are most often used for medical purposes. The most famous representative of salicylates is acetylsalicylic acid, i.e. aspirin. Like many derivatives of salicylic acid, acetylsalicylic acid also contains anti-inflammatory properties and is widely distributed. Salicylic acid was isolated back in the 19th century, when it was believed that willow bark has anti-inflammatory effects. The popularity of salicylic acid increased due to its various applications, and methods for its determination and for the determination of salicylates began to develop. Due to the increased popularity of salicylic acid, its consumption has also increased, which increases the need to determine its concentration in the environment, water and products. In this paper, the five most commonly used methods for determining the presence of salicylic acid and its derivatives are discussed. These methods are: colorimetric determination, spectrofluorimetry, liquid chromatography with high resolution of reversed phases, potentiometry and voltammetry
Assessment of the impact of the COVID-19 pandemic on the air in the Kopački rit Nature Park
No full textZrak je neophodan za život na zemlji. Onečišćenju zraka pridonose zagađivači u atmosferi prisutni u graničnom sloju atmosfere. Ozon, PM10 čestice i benzen neki su od onečišćivača u zraku. Uvelike utječu na ekosustav, remeteći prije svega zdravlje čovjeka, kao i biljni i životinjski svijet. U ovom radu procijenjene su koncentracije ozona, benzena i PM10 čestica na dvije različite lokacije (Park prirode Kopački rit i grad Osijek) istočne Hrvatske za razdoblje prije SARS-CoV-2 (COVID-19) pandemije, točnije prije "lockdowna", i na početku popuštanja mjera (2018.-2021.godine). Koncentracije ozona u Kopačkom ritu uspoređene su s istima u Osijeku jer su ove dvije lokacije interesantan primjer međusobnog utjecaja ruralnog i urbanog područja na relativno maloj udaljenosti. Prosječne srednje vrijednosti koncentracija PM10 čestica za promatrano razdoblje su veće na području Osijeka u odnosu na Park prirode Kopački rit. Vrijednosti koncentracija benzena u Osijeku svoj maksimum postižu u večernjim satima, dok u Kopačkom ritu u jutarnjim satima. Uočeno je kako se koncentracija ispitivanih onečišćivača smanjila u razdoblju "lockdowna" u odnosu na razdoblje prije.Air is necessary for life on earth. Contaminants in the atmosphere present in the boundary layer of the atmosphere contribute to air pollution. Ozone, PM10 particles and benzene are some of the pollutants in the air. They affect the ecosystem, first of all disrupting human health, as well as plant and animal life. In this paper, the concentrations of ozone, benzene and PM10 particles were estimated at two different locations (Kopački rit Nature Park and the city of Osijek) in eastern Croatia for the period before the SARS-CoV-2 (COVID-19) pandemic, more precisely before the "lockdown", and at the beginning of the easing of measures (2018-2021). Ozone concentrations in Kopački rit were compared with those in Osijek, because these two locations are an interesting example of the mutual influence of rural and urban areas at a relatively short distance. The average mean values of the concentration of PM10 particles for the observed period are higher in the area of Osijek compared to the Kopački rit Nature Park. Benzene concentration values in Osijek reach their maximum in the evening hours, while in Kopački rit in the morning hours. It was observed that the concentration of the tested pollutants decreased during the "lockdown" period compared to the previous period
Study of the application of selected citrus fruit as acid-base indicator
No full textU današnjim laboratorijima, upotreba indikatora se bazira više na sintetskim indikatorima, nego na indikatorima dobivenim iz biljnih materijala. Istraživanjem biljnog materijala, povrća i voća, kao eventualnih kiselo-baznih indikatora te prihvaćanjem naučenih činjenica o istima kemija se povezuje sa svakodnevnim životom te se na taj način lakše predočava laicima. Upravo iz tih razloga ovaj rad za cilj ima ispitivanje eventualne primjene biljnog materijala (točnije, citrusa) kao kiselo-baznog indikatora. U ispitivanjima je korištena kora i sok šest vrsti citrusa u kombinaciji s pojedinim otapalima (hladna voda, vrela voda, etanol, aceton, metanol). Ispitivanja su provedena u nekoliko faza, odmah nakon pripreme indikatora (pri sobnoj temperaturi), nakon 24 h stajanja na sobnoj temperaturi, nakon sedam dana stajanja u hladnjaku te nakon 14 dana stajanja u hladnjaku. Dobiveni rezultati potvrđuju potencijal pojedinog citrusnog voća za izradu prirodnih pH indikatora. Najperspektivnijim za izradu prirodnih indikatorima su se pokazali kora limete te kora pomela.In today's laboratories, the use of indicators is based more on synthetic indicators than on indicators obtained from plant materials. By researching plant material, vegetables and fruits, as potential acid-base indicators, and by accepting the learned facts about them, chemistry is connected to everyday life and, for that reason easier to present to laymen. Precisely for these reasons, this paper aims to examine the possible application of plant material (more precisely, citrus) as an acid-base indicator. The tests used the peel and juice of six types of citrus fruits in combination with solvent (cold water, hot water, ethanol, acetone, or methanol). The tests were carried out in several stages, immediately after the preparation of the indicator (at room temperature), after 24 hours of standing at room temperature, after seven days of standing in the refrigerator and after 14 days of standing in the refrigerator. The obtained results confirm the potential of some of used citrus fruit for the preparation of natural pH indicators. Lime peel and pomelo peel showed the most promising result
Optimization of vitamin E extraction method from real samples
No full textU ovome završnom radu je određivan sadržaj vitamina E u uzorcima hrane za nesilice korištenjem tekućinske kromatografije visoke djelotvornosti. Ispitivan je utjecaj promjene različitih parametara kao što su sastav ekstrakcijske smjese, omjer suhe tvari i ekstrakcijske smjese i veličina čestica uzorka na određivanje sadržaja vitamina E u realnim uzorcima. Za ekstrakciju je upotrebljena već korištena metoda. Ekstrakcija je uspješnija korištenjem usitnjene hrane za nesilice, jer je veća aktivna površina i može se ekstrahirati više vitamina E. Najviše vitamina E ekstrahirano je kada je omjer suhe tvari i ekstrakcijske smjese 1:50 uz izmijenjeni sastav ekstrakcijske smjese (u odnosu na sastav ekstrakcijske smjese u već korištenoj metodi) - 5 mL 0.2 %-tne otopine BHT (2,6-di-tert-butyl-4-methylphenol) u metanolu, 5 mL 40%-tne otopine kalijeva hidroksida u metanolu, 5 mL ultračiste vode te 10 mL otopine heksana i etil-acetata u omjeru 65:35.In this final paper, the content of vitamin E in food samples for laying hens was determined by using high-performance liquid chromatography. The impact of changing various parameters such as the composition of the extraction mixture, the ratio of dry matter to the extraction mixture and the size of the sample particles on the determination of the vitamin E content in real samples was examined. The already known method was used for extraction. Extraction is more successful using shredded feed for laying hens, because the active surface is larger and more vitamin E can be extracted. The most vitamin E was extracted when the ratio of dry matter to the extraction mixture was 1:50 with a changed composition of the extraction mixture (compared to the composition of the extraction mixture in the already used method) - 5 mL of a 0.2% BHT solution (2,6-di -tert-butyl-4-methylphenol) in methanol, 5 mL of a 40% solution of potassium hydroxide in methanol, 5 mL of ultrapure water and 10 mL of a solution of hexane and ethyl acetate in a ratio of 65:35
Study of the application of selected solvents in the preparation of alternative acid-base indicators
No full textU kemiji se otapala gotovo uvijek koriste bilo kao medij u kojem se odvija reakcija ili kao sam sudionik reakcije. Otapala vrlo često služe i za ekstrakciju biljnih pigmenata poput antocijanina. Takvi pigmenti u različitim pH sredinama pokazuju širok spektar boja poput crvene, ružičaste, ljubičaste, plave, žute, zelene pa čak i sive. Upravo to omogućuje uporabu biljnih materijala bogatih antocijaninima i polifenolima kao alternativnih kiselo-baznih indikatora. Cilj rada bio je istražiti uporabu odabranih otapala u pripremi alternativnih kiselo-baznih indikatora. Biljni materijali koji su se koristili bili su svježi, suhi i voćne prerađevine. Voćne prerađevine koje su se koristile sadržavale su najveći mogući sadržaj odabranog biljnog materijala, bez dodanog drugog voća, umjetnih bojila i drugih potencijalih kiselo-baznih indikatora. Rezultati istraživanja pokazuju vrlo visok potencijal korištenja određenih otapala u pripremi alternativnih kiselo-baznih indikatora. Biljni materijali koji su se vizualno najbolje istakli su aronija, crna malina, crni ribiz, crni dud i borovnica.In chemistry, solvents are frequently used either as a medium for the reaction or as a participant in the reaction itself. Solvents are often used to extract plant pigments such as anthocyanins. These pigments in different pH environments show a wide range of colors such as red, pink, purple, blue, yellow, green and even gray. This is precisely what makes plant material rich in anthocyanins and polyphenols appropriate to be used as alternative acid-base indicators. The aim of this thesis was to explore the use of selected solvents in the preparation of alternative acid-base indicators. Used plant materials were fresh, dry and fruit products. Used fruit products contained the highest possible content of selected plant material, without other fruits, artificial colors or other potential acid-base indicators. The research results show a very high potential of using certain solvents in the preparation of alternative acid-base indicators. The plant materials that visually stand out the best are chokeberries, black raspberries, blackcurrants, black mulberries and blueberries
Synthesis and Characterization of the Carbon Quantum Dots from Citrus clementina peel: Investigation of the Antiradical Activity of Metal Ions Detection
No full textUgljikove kvantne točke su relativno nova vrsta fluorescentnih ugljikovih nanomaterijala, koje su zahvaljujući svojim izvanrednim kemijskim i optičkim svojstvima, odličnoj biokompatibilnosti i razmjerno jednostavnoj mogućnosti sinteze, privukle ogromnu pozornost mnogih znanstvenika. Također, zahvaljujući mogućnosti modifikacije površine u svrhu postizanja što boljih svojstava, njihova primjena kao fluorescentnih nanoprobi nije ograničena, dapače, pronašle su svoju primjenu u širokom spektru analiza; u biomedicini, kontroli kvalitete vode i hrane, kontroli okoliša i pesticida. U ovom diplomskom radu, hidrotermalnom sintezom, koristeći liofiliziranu koru klementine kao prekursor i 5 različitih aminokiselina (Leu, Trp, Arg, Ala, His) kao dopante dušika, pripremljene su N-dopirane ugljikove kvantne točke. Sintetiziran je i blank sustav, čisti nedopirani sustav, pripremljeni koristeći samo prekursor kore klementine. Proučavane su razlike između kemijskih, strukturnih, optičkih i bioloških svojstava pripremljenih ugljikovih kvantnih točaka (CQDs). Ugradnja dušika u strukturu CQDs sintetiziranih iz biomase rezultirala je povećanjem kvantnog iskorištenja i poboljšanja svojstava i osjetljivosti dobivenih fluorescentnih nanoproba u usporedbi s blank sustavom. Najbolje kvantno iskorištenje (QY) pokazao je CQD@Arg, QY = 4,59 %. Rezultati su pokazali slična optička svojstva pripremljenih CQDs, a razlike su uočene prilikom selektivne detekcije metalnih iona i ispitivanja na antiradikalnu aktivnost. Najveću antiradikalnu aktivnost pokazao je CQD@Trp, DPPH metodom od 99,85±0,26 %, dok je najbolja vrijednost EC50 = 17,94±1,12 μg/mL utvrđena kod blank uzorka. Nadalje N-dopirane CQDs su korištene kao fluorescentne nanoprobe prilikom selektivne detekcije metalnih iona.Carbon quantum dots are a relatively new type of fluorescent carbon nanomaterials, which, thanks to their outstanding chemical and optical properties, excellent biocompatibility and relatively simple synthesis, have attracted the enormous attention of many scientists. Also thanks to the possibility of modifying the surface in order to achieve the best possible properties, their application as fluorescent nanoprobes is not limited, in fact they have found their application in a wide range of analyses; in biomedicine, water and food quality control, environmental and pesticide control. In this thesis, N-doped carbon quantum dots were prepared by hydrothermal synthesis, using lyophilized clementine peel as a precursor and 5 different amino acids (Leu, Trp, Arg, Ala, His) as nitrogen dopants. A blank system, a pure undoped system, prepared using only the precursor, was also synthesized. The differences between the chemical, structural, optical and biological properties of the prepared carbon quantum dots (CQDs) were studied. Incorporation of nitrogen into the structure of carbon quantum dots synthesized from biomass resulted in an increase in quantum yield and improved properties and sensitivity of the obtained fluorescent nanoprobes, compared to the blank system. The best quantum yield (QY) was shown by CQD@Arg, QY = 4.59%. The results showed similar optical properties of the prepared CQDs, and differences were observed during the selective detection of metal ions and testing for antiradical activity. The highest antiradical activity was shown by CQD@Trp, using the DPPH radical removal method of 99.85±0.26%, while the best EC50 value = 17.94±1.12 μg/mL was determined for the blank sample. Furthermore, N-doped CQDs were used as fluorescent nanoprobes for the selective detection of metal ions