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The mechanochemical synthesis of calcium oxalate
No full textOva studija prikazuje mehanokemijsku sintezu kalcijeva oksalata u planetarnom kugličnom mlinu, bez i uz prisutnost otapala. Dosadašnja istraživanja su uglavnom bila usmjerena na otopinsku sintezu kalcijeva oksalata. U ovom radu opisujemo drugačiji pristup, koji će donijeti nova saznanja o sintezi kristala kalcijeva oksalata, a koje su uzrokovane utjecajem mehaničke energije. Cilj istraživanja je sinteza, identifikacija i karakterizacija pojedine oksalatne hidratne faze sintetizirane iz kalcijevih soli (klorida, nitrata i sulfata). Ispitivan je utjecaj brzine mljevenja i praćena je reakcija u ovisnosti o vremenu sinteze. Strukturalna i termička svojstva uzoraka ispitana su FTIR spektroskopijom i termogravimetrijskom analizom (TGA). Morfološke karakteristike kalcijeva oksalata te raspodjela veličine čestica određene su optičkom mikroskopijom i dinamičkim raspršenjem svjetlosti (DLS).In this work, mechanochemical synthesis of calcium oxalate was done in planetary ball mill, with and without addition of water as a solvent. Previous researches were primarily focused on calcium oxalate synthesis in a solution. Here we report a different approach which may contribute to new findings in calcium oxalate crystal synthesis caused by an influence of mechanical energy. The aim of this study is synthesis, identification and characterization of particular oxalate hydrate phase synthesized with calcium salts (chloride, nitrate and sulphate). The effects of grinding speed and reaction duration regarding the time of synthesis were investigated. Structural and thermal sample properties were studied by FTIR spectroscopy and thermogravimetric analysis (TGA). Morphologic characteristics of calcium oxalate and size distribution were measured by optical microscopy and dynamic light scattering (DLS)
Deacetylation of Chitosan and characterization of the deacethylation products
No full textKitozan je prirodni polimer koji zahvaljujući svojim kemijskim i biološkim karakteristikama pronalazi ulogu u gotovo svim područjima ljudske djelatnosti, od medicine i farmacije do očuvanja okoliša. Kitozan je kopolimer dobro topljiv u vodi, izgrađen od dvije vrste ponavljajućih monomernih jedinica: N-acetil-2-amino-2-deoksi-D-glukopiranoza i 2-amino-2- deoksi-D-glukopiranoza. Kemijskim putem nastaje N-deacetilacijom hitina, dok ga se u prirodi može pronaći kod određenih tipova gljivica. Nadalje, kitozan karakterizira visok stupanj netoksičnosti, biokompatibilnosti i biorazgradivosti te upravo zahvaljujući tim osobinama pronašao je svoju ulogu u očuvanju okoliša; vrlo je koristan kelirajući agens teških metala otpadnih voda i lebdećih čestica. Kitozan se može pripraviti iz egzoskeleta člankonožaca; prvo se izolira hitin, a nakon toga se u procesu deacetilacije dobiva kitozan, koji je primjenjiv kao polazna sirovina za kemijsku sintezu određenih produkata korisnih u medicini, farmaciji i zaštiti okoliša. Molekularna masa, odnosno njezina distribucija unutar polimera znatno utječe na fizikalna i kemijska svojstva polimera kao što su na primjer reološka i mehanička svojstva kitozana. Molekularna masa i njezina distribucija unutar polimera također uvelike utječe na mogućnost stvaranja gel formacije, modifikaciju osmotskog tlaka, povišenje viskoznosti i stvaranje vlakana, a navedena svojstva su od iznimne važnosti prilikom korištenja kitozana kao polazne sirovine za proizvodnju različitih korisnih produkata u industriji hrane, medicini i farmaciji. U ovom završnom rada utvrđeno je na koji način temperatura i vrijeme trajanja reakcije deacetilacije kitozana pod umjerenim okolnostima utječu na molekularnu masu i stupanj deacetilacije (DD) deacetiliranog kitozana. Za određivanje molekularne mase kitozana korištena je metoda statičkog raspršenja svjetlosti pomoću Malvern Zetasizer Nano S instrumenta, dok je za određivanje stupnja deacetilacije (DD) kitozana korištena FT-IR spektroskopska metoda. Povišenjem temperature i povećanjem vremena trajanja reakcije deacetilacije kitozana dolazi do povećanja stupnja deacetilacije (DD) kitozana. Nadalje, povišenjem temperature i povećanjem vremena trajanja reakcije deacetilacije kitozana dolazi do smanjenja molekularne mase kitozana odnosno hidrolize polimernog lanca. Pomoću rezultata dobivenih u ovom radu može se pripraviti kitozan sa željnom molarnom masom i stupnjem deacetilacije što uveliko doprinosi upotrebljivosti i eksploataciji kitozana na različitim znanstvenim i industrijskim poljima.Chitosan is a natural polymer which, due to its chemical and biological characteristics, has a role in almost all areas of human activity, from medicine and pharmacy to environment protection. It is a water-soluble copolymer, composed of two types of repetitive monomeric units: N-acetyl-2-amino-2-deoxy-D-glucopyranose and 2-amino-2-deoxy-D-glucopyranose. It can be produced by N-deacetylation of the chitin using chemical processes, and it can be found in nature with certain types of fungi. Furthermore, chitosan is characterized by a low level of toxicity and prominent level of biocompatibility and biodegradability. Due to these properties, chitosan has found its role in environment protection; it is a very useful chelating agent for heavy metals in wastewaters and particulate matter (PM). Chitosan can be produced from the exoskeleton of the arthropod; first, the chitin is isolated, and then in the process of deacetylation is performed to obtain chitosan. It can be then used as a starting material in chemical synthesis of certain products used in medicine, pharmaceutical industry of drugs and environment protection. The molecular weight and its distribution affect physical and chemical properties of polysaccharides such as the rheological, mechanical properties and pore size of membranes or microcapsules made of chitosan. Therefore, molecular weight determination is very important for elucidating the characteristics of the chitosan itself and the products made from it. Gel forming, osmotic pressure modification, viscosity enhancing, or fiber formation also depend on molecular weight and its distribution which have been used in food industrial, pharmaceutical, and medical applications. In this bachelor thesis it is investigated how does reaction temperature and duration time of deacetylation reaction under the mild conditions effect the degree of deacetylation (DD) and molecular weight of deacetylated chitosan. To determine molecular weight of deacetylated chitosan, static light scattering (SLS) method is used by Malvern Zetasizer Nano S instrument while the degree of deacetylation was determined by infrared spectroscopy (FT-IR). By increasing the reaction temperature and time of deacetylation reaction, the degree of deacetylation (DD) have increased. Furthermore, by increasing reaction temperature and time duration of deacetylation reaction, decrease of molecular weight or hydrolysis of polymer chain is also noticed. By the results obtained in this thesis we can prepare chitosan with desired molecular weight and degree of deacetylation what makes chitosan more exploitable and applicable in variety of scientific and industrial fields
Investigation of the influence of sensor material concentration at the surfactant sensor response characteristic
No full textProvedena su potenciometrijska mjerenja korištenjem senzora s različitim udjelom senzorskog materijala (1 %, 3 % i 5 %) tetraoktadecilamonijevog tetrafenilborata (TODA-TPB) i -nitrofeniloktileterom (-NPOE) kao plastifikatorom. Ispitivanje je provedeno kako bi se moglo odrediti utječe li koncentracija senzorskog materijala na odzivne karakteristike senzora. Ispitivanje utjecaja koncentracije senzorskog materijala na odzivne karakteristike tenzidnog senzora provedeno je metodom direktne potenciometrije, dok je za kondicioniranje senzora korištena potenciometrijska titracija. Za mjerenje odzivnih karakteristika senzora korišteni su natrijev dodecil sulfat (NaDDS, = 5· mol/L, = 1· mol/L) i natrijev dodecilbenzen sulfonat (NaDBS, = 5· mol/L, = 1· mol/L) a mjerenja su provedna u vodi i natrijevom sulfatu (, = 1· mol/L). Za potenciometrijske titracije korišten je NaDDS ( = 4· mol/L) koji je titriran sa cetilpiridinijevim kloridom (CPC, = 4· mol/L). Rezultati odzivnih karakteristika senzora pokazali su sub-Nernstovski odziv u rasponu od -54,2 mV/ dekadi aktiviteta do -55,8 mV/ dekadi aktiviteta. Najnižu granicu detekcije, 5· mol/L, pokazao je senzor s 1 % senzorskog materijala. Istraživanjem se utvrdilo da su sva tri senzora pogodna za određivanje niskih koncentracija NaDDS i NaDBS te da nema značajnije razlike u karakteristikama senzora s različitim udjelom senzorskog materijala.Potentiometric measurements using sensors with different content (1 %, 3 % and 5%) of ion pair tetraoctadecylamonium tetraphenylborate (TODA-TPB) as sensing material and -nitrophenyl octil eter (-NPOE) as a plasticizer were performed. Investigation was carried out in order to determine whether the concentration of the sensing material has an effect on the response characteristics of sensor. The direct potentiometric method was used for investigation of response characteristics of the sensors, while the potentiometric titration was used for conditioning the sensors. Sodium dodecyl sulfate (NaDDS, = 5· mol/L, = 1· mol/L) and sodium dodecylbenzene sulfonate (NaDBS, = 5· mol/L, = 1· mol/L), were used to measure the response characteristics of the sensors in water and sodium sulfate (, = 1· mol/L). Potentiometric titration were carried out using NaDDS ( = 4· mol/L) as analyte and cetylpyridinium chloride (CPC, = 4· mol/L) as titrans. The results of investigation of response characteristics of the sensor showed sub-Nernstian response ranging from -54,2 mV/ decade of activity to -55,8 mV/decade of activity. The lowest detection limit of 5· mol / L exhibited sensor with 1 % sensor material. The study found that all three sensors are suitable for determining low concentrations of NaDDS and NaDBS and that there is no significant difference in sensor characteristics with a different concentration of sensing material
Synthesis and chemical modification of silica and biodegradiable nanoparticles
No full textSilikatne nanočestice su sintetizirane hidrolizom alkil silikata i postupnom kondenzacijom silikatne kiseline u alkoholnoj otopini uz amonijak kao katalizator. Promjena koncentracije amonijaka u rasponu od 0,05 do 0,70 uzrokuje promjenu veličine čestica od 13 nm do 87 nm. Funkcionalizacija silikatnih nanočestica je izvršena dodavanjem modifikatora nakon završene sinteze čestica. Matematičkim izračunima, podešavanjem pH vrijednosti i mjerenjem zeta potencijala postavljeni su uvjeti kontrolirane agregacije. Kontrolirana agregacija temelji se na elektrostatskim privlačnim silama između pozitivno i negativno nabijenih čestica koje tvore određeni uzorak agregiranja. Kitozanske nanočestice pripravljene su iz emulzije isparavanjem otapala, povećavanjem koncentracije polisorbata 20 u intervalu od 1∙ do 5∙ su dobivene kitozanske nanočestice veličine od 32,67 nm do 78,66 nm s 0,44% masenog udjela kitozana. Čestice su okarakterizirane dinamičkim raspršenjem svjetlosti (DLS) i transmisijskim elektronskim mikroskopom (TEM), mjerenja zeta potencijala izvršena su s elektroforetskim raspršenjem svjetlosti (ELS) te je kemijska modifikacija potvrđena infracrvenom spektroskopijom s Fourierovom transformacijom (FT-IR). Na kraju rada, opisan je i metodički dio na temu "Građa atoma" za prvi razred gimnazijskog programa srednje škole.Silica nanoparticles are prepared with hydrolysis of alkyl silica followed by subsequent condensation silicic acid in alcohol with ammonia catalyst. Ammonia concentration ranging from 0,05 to 0,70 , causes a change in particles size from 13 nm to 87 nm. Silica nanoparticles are functionalized by post-modification. Mathematical calculation, adjusting pH and zeta potential measurement are necessary for controled aggregation. Electrostatic attractive forces between positive and negative particles are basis for controled agreggation with pattern. Emulgation solvent evaporation is method for preparation chitosan nanoparticles, changing concentration polysorbate 20 from 1∙ to 5∙ , resulted in particles size from 32,67 nm to 78,66 nm, with 0,44% chitosan. Particles are characterized with dynamic light scattering (DLS) and transmission electron microscopy (TEM), electrophoretic light scattering (ELS) is used to measure zeta potential, and chemical modification is confirmed with Fourier-transform infrared spectroscopy (FT-IR). Thesis contains a part with teaching method on subject "Atom structure" for first class of high school
Preparation of quaternary salts of nicotinamide with supstituted phenacyl bromides in a microwave reactor
No full textKvaterne soli heterocikličkih amina kao što je nikotinamid imaju širok spektar terapijskih učinaka, a koriste se kao antibakterijska i antikancerogena sredstva. U ovom su radu izvedene reakcije kvaternizacije potpomognute mikrovalnim zagrijavanjem nikotinamida sa supstituiranim fenacil-bromidima u acetonu. Prinos sinteze pomoću mikrovalnog zagrijavanja u acetonu je uspoređen s konvencionalnim zagrijavanjem. Budući da reakcija stvaranja soli nikotinamida pripada reakciji nukleofilne supstitucije (), prinos produkta je pod utjecajem strukture reagensa, nikotinamida i elektrofila. Istražen je utjecaj strukture elektrofila na prinos reakcije kvaternizacije. Elektrofili su supstituirani fenacil-bromidi s različitim elektron akceptorskim i elektron donorskim skupinama u para- i ortho položaju.Quaternary salts of heterocyclic amines like nicotinamide have a wide range of terapeutic effects, they have been used as antibacterial and anticarcinogenic agents. In this thesis reaction of quaternization under microwave heating of nicotinamide with substituted phenacyl bromides in acetone was performed. The synthesis yield by microwave heating in acetone is compered to conventional heating. Since the reaction of formation of nicotinamide salts belongs to the reaction of nucleophilic substitution () the yield of the product is affected by the structure of boath reagents, nicotinamide and electrophiles. The influence of structure of electrophile on the quaternization reaction yield was investigated. Electrophiles are phenacyl bromides with different electron withdrawing and electron donating substituents in para- and ortho- position
Autoimmune disorders
No full textImunološki sustav kontrolira sve patogene vrste u organizmu i na taj način sprječava različita oštećenja i bolesti. Ključna reakcija je reakcija protutijela i antigena koja potiče imunološki odgovor. Konačan cilj je apoptoza ciljane stanice, a ostvaruje se nizom složenih mehanizama u koji su uključeni različiti proteini, kompleksi i receptori pri čemu je naglasak na mehanizmu aktivacije T- i B-stanica, a ključan je i mehanizam odabira T-stanica koji ispravnom pozitivnom i negativnom selekcijom osigurava napad na nepoželjno tkivo. U slučaju pogrješke, imunološki sustav može napasti vlastite antigene pri čemu se razvijaju autoimuni poremećaji. Takve poremećaje dijelimo u dvije skupine: sustavna imunost i specifična autoimunost organa. Sustavna autoimunost uključuje bolesti vezivnog tkiva, dok specifična autoimunost organa obuhvaća točno određene organe. Postavljanje dijagnoze temelji se na upotrebi biomarkera kao što su različiti geni, proteini, receptori te antitijela. Na razvoj autoimunih poremećaja utječu i brojni čimbenici od kojih su najvažniji: genetika, spol, dob, etnička pripadnost i okoliš. Budući izgledi u liječenju autoimunih poremećaja podrazumijevaju primjenu lijekova kao što su kortikosteroidi i imunosupresivni lijekovi. Osim toga, važan je napredak medicine koji uključuje operacije, zatim razvoj novih tehnologija i tehnika. Prije svega, najutjecajniji lijek protiv autoimunih poremećaja je odgovornost svakoga čovjeka prema samome sebi.The immune system is a system that controls all pathogenic species in the organism and thus prevents various damage and diseases. The key reaction is the reaction of antibodies and antigens that stimulate the immune response. The ultimate goal is the apoptosis of the target cell, and it is realized by a series of complex mechanisms involving different proteins, complexes and receptors, with an emphasis on the activation mechanism of T and B cells, and the T-cell selection mechanism is also crucial. With the correct positive and negative selection, T-cell selection mechanism provides an attack on unwanted tissue. In the event of a mistake, the immune system can attack its own antigens, where by autoimmune disorders develop. Autoimmune disorders are divided into two groups: systemic immunity and specific autoimmunity of organs. Systemic autoimmunity involves connective tissue disorders, while specific autoimmunity of organs includes exact organs. The diagnosis is based on the use of biomarkers such as various genes, proteins, receptors and antibodies. The development of autoimmune disorders is also influenced by many factors, most important of which are genetics, sex, age, ethnicity and the environment. Future prospects in the treatment of autoimmune disorder simply the use of drugs such as corticosteroids and immunosuppressive drugs. In addition, important advances in medicine include operations, then the development of new technologies and techniques. First of all, the most influential anti-autoimmune remedy is the responsibility of every man to himself
The role of lutein in human body and determination of its concentration in eggs by UV-VIS spectrophotometry
No full textLutein je pigment koji pripada skupini karotenoida ne-provitamina A kao i njegov izomerzeaksantin. Ljudski organizam ga ne može sintetizirati kao biljke, pa ga mora unositi hranom budući da mu je potreban za normalnu funkciju. Najveća koncentracija luteina u čovjeku se nalazi u žutoj pjegi gdje služi kao zaštita od zračenja visoke energije pa njegov nedostatak može uzrokovati probleme s vidom. UV-VIS spektrofotometrija je analitička metoda pogodna za kvalitativnu i kvantitativnu analizu. Apsorpcijski maksimum luteina je na valnoj duljini od oko 445nm što pripada vidljivom djelu spektra što ga čini pogodnim za proučavanje ovom metodom. Standardnim otopinama luteina različitih koncentracija su snimljeni apsorpcijski spektri te je ovisnost koncentracija i apsorpcije prikazana baždarnim dijagramom. Lutein je izoliran iz žumanjaka domaćih i komercijalnih jaja pomoću acetona te je otopljen u heksan-etil acetatu. Svakom uzorku je spektrofotometrijski određena apsorbancija te je pomoću baždarnog dijagrama određena koncentracija. Dobiveni rezultati ukazuju na puno veću koncentraciju luteina u domaćim jajima nego u komercijalnim. Cilj ovoga istraživanja je spektrofotometrijski odrediti koncentraciju luteina iz žumanjka jaja, komercijalnih i domaćih, te usporediti dobivene rezultate.Lutein is a pigment belonging to the non-provitamin A carotenoid group as well as its isomeric zeaxanthin. The human organism can not synthesise lutein as a plant, so it must be taken in by food as it is needed for a normal function. The highest concentration of lutein in humans is in the macula where it serves as a protection against high-energy radiation, so the lack of lutein can cause vision problems. UV-VIS spectrophotometry is an analytical method suitable for qualitative and quantitative analysis. The absorption peak of lutein is on the wavelenght of around 445 nm which belongs to the visible part of the spectrum and that makes lutein suitable for analysis whith this method. Standard lutein solutions of different concentrations are captured by absorption spectrum and the dependence of concentration and absorbency is shown by a calibration diagram. Lutein is isolated from egg yolks of domestic and commercial eggs by acetone and dissolved in hexane-ethyl acetate. Absorption of each sample was spectrophotometrically determined and concentration was calculated using the calibration diagram. The obtained results indicate a much higher concentration of lutein in domestic eggs than in commercial. The aim of this study is to determine the concentration of lutein in commercial and domestic egg yolks and to compare the results
Concentrations of selnium in water, soil, vegetables and biological specimens of an eastern Croatian population
No full textCilj ovoga rada bio je odrediti koncentraciju selena u uzorcima bioloških materijala (urin, kosa, serum 500 stanovnika s područja istočne Hrvatske. Koncentracije selena određene su na nekim lokacijama i u uzorcima vode, biljaka i tla. Vrijednosti medijana kretale su se u sljedećim rasponima vrijednosti: serum od 80,75 μg do 113,92 μg , urin od 12,44 μg do 36,31 μg , kosa od 0,20 μg do 0,60 μg . Prosječne vrijednosti : voda 1,95 μg , zemlja od 0,02 do 0,36 μg , povrće (kupus) od 22,61 do 201 μg , maslačak od 18,30 do 133,4 μg . Istraživanje je provedeno na velikom broju uzoraka, stoga rezultati ovoga rada služe doprinose značajno proširenju baze referentnih podataka za područje Hrvatske.The goal of this work was to determine the concentration of selenium in biological materials samples (urine, hair, and serum) of 500 residents from 5 towns and 3 villages in eastern Croatia. Selenium concentrations were also determined in some of the collected samples of water, plants, and soil. The analyzed results for the median span: serum from 80,75 μg till 113,92 μg , urine from 12,44 μg till 36,31 μg , hair from 0,20 μg till 0,60 μg . Mean: water 1,95 μg , soil from 0,02 till 0,36 μg , vegetables (Cabbage) from 22,61 till 201 μg , Dandelion from 18,30 till 133,4 μg . The research was carried out on a large number of samples, therefore the results of this paper contribute to the significant expansion of the reference database for Croatia
Effects of exhaust gases on the health and the environment
No full textNastankom modernog društva i razvitkom industrije i prometa došlo je do problema zagađenja okoliša. Kao glavni izvor energije se koriste fosilna goriva čijim izgaranjem nastaju ispušni plinovi. Ispušne plinove čine vodena para, ugljikov (IV) oksid, ugljikov (II) oksid, dušikovi oksidi, sumporov (IV) oksid, ugljikovodici, aerosoli teških metala te čađa i dim. Glavni zagađivači ispušnim plinovima su industrija i promet. Cestovni promet je puno veći zagađivač od zračnog i željezničkog prometa. Željeznički promet je ekološki najprihvatljiviji oblik putovanja i transporta. Zauzima najmanje mjesta, ima najmanje emisije ispušnih plinova i energetski je vrlo učinkovit. Ispušni plinovi imaju negativne utjecaje na okoliš i zdravlje ljudi. Zbog tih negativnih utjecaja istražuju se načini smanjenja količine ispušnih plinova i uvode se zakoni koji ograničavaju dopuštene količine ispušnih plinova u zraku. Smanjenje količine ispušnih plinova se može postići uporabom alternativnih goriva i okretanjem obnovljivim izvorima energije.With the establishment of modern society and the development of industry and traffic, problem of environmental pollution has emerged. The main sources of energy are fossil fuels whose combustion produces exhaust gases. Exhaust gases include water vapor, carbon (IV) oxide, carbon (II) oxide, nitrogen oxides, sulfur (IV) oxide, hydrocarbons, heavy metal aerosols, soot and smoke. The main pollutants of exhaust gases are industry and traffic. Road traffic is a much larger polluter than air and rail traffic. Rail traffic is the most environmentally acceptable form of travel and transportation. It takes up the minimum of space, has the lowest emissions of exhaust gases and is energy efficient. Exhaust gases have negative impacts on the environment and human health. Because of these negative impacts, methods of reducing the amount of exhaust gases are being researched and laws restricting the permitted amount of exhaust gases in the air are introduced. Reducing the amount of exhaust gases can be achieved by the use of alternative fuels and turning to renewable energy sources
N-end rule in protein stability
No full textProteini su osnovna građevna jedinica koja se gradi povezivanjem 20 različitih aminokiselina u polipeptidne lance. Svaka od 20 aminokiselina razlikuje se po svojstvima zbog svoje strukture odnosno zbog različitih bočnih ogranaka. Aminokiseline se povezuju peptidnom vezom i tvore četiri razine struktura proteina: primarnu, sekundarnu, tercijarnu i kvaternu. Svojstva proteina, pa i sama njihova stabilnost, ovisna su o redoslijedu njihovih aminokiselinskih ostataka. Od 1986. godine, kada je pravilo N-kraja postavljeno, provode se istraživanja kod eukariota i prokariota i dobivaju detaljniji podaci o samoj stabilnosti proteina. N-pravilo ukazuje kakva je stabilnost određenog proteina te koliko mu je vrijeme poluživota. Dvije grane N-pravila kod eukariota su pravilo Arg/N i pravilo Ac/N. Svaka grana ima svoj način prepoznavanja proteina za ubikvitinaciju. Pravilom N-kraja utvrđene su funkcije mnogih proteina i enzima te same koristi od N-kraj puta. Ubikvitinirani proteini se u proteosomu proteolitički razgrađuju. Prokariotske stanice imaju sličan način prepoznavanja proteina, ali drugačiji način obilježavanja bez ubikvitina te kompleks proteolitičkih proteina razgrađuje drugačijim mehanizmom. U ovome će se radu kratko objasniti osnove o proteinima, njihova stabilnost ovisna o bočnim ograncima, pravilo N-kraja, njegove grane, funkcije i sam mehanizam razgradnje proteina kod eukariota i prokariota.Proteins are a basic building block built by connecting 20 different amino acids in the polypeptide chain. Each of the 20 amino acids differs in properties due to their structure or due to different amino acid residue. Amino acids are linked together with peptide bonds and form four levels in protein structure: primary, secondary, tertiary and quaternary. Protein properties and the protein stability itself depends on sequence of the amino acids residues that make up a particular protein. Since 1986, when the N-rule rule has been set up, studies into eukaryotes and prokaryotes are conducted to get more detailed data on protein stability. The N-rule indicates the stability of a given protein and how long its half-life is. The two branches of the N-rules in the eukaryotes are the Arg/N rule and the Ac/N rule. Each branch has its own way of recognizing proteins for ubiquitination. The N-end rule has determined the functions of many proteins and enzymes. Ubiquitinated proteins are degraded proteolytically in the proteosome. Prokaryotic cells have a similar way of recognizing proteins, but a different way of marking without ubiquitin and the proteolytic protein complex is working by a different mechanism. This paper will briefly explain the basics of proteins, their stability dependent on aminoacid residues, the N-line rule, its branch, function, and the mechanism of degradation of proteins in eukaryotes and prokaryotes