Uloga tiolne grupe u modifikaciji proteina sa metilglioksalom

Methylglyoxal is a highly reactive a-oxoaldehyde with elevated production in hyperglycemia. It reacts with nucleophilic Lys and Arg side-chains and N-terminal amino groups causing protein modification. In the present study, the importance of the reaction of the Cys thiol group with methylglyoxal in protein modification, the competitiveness of this reaction with those of amino and guanidine groups, the time course of these reactions and their role and contribution to protein cross-linking were investigated. Human and bovine serum albumins were used as model systems. It was found that despite the very low levels of thiol groups on the surface of the examined protein molecules (approx. 80 times lower than those of amino and guanidino groups), a very high percentage of it reacts (25-85%). The amount of reacted thiol groups and the rate of the reaction, the time for the reaction to reach equilibrium, the formation of a stable product and the contribution of thiol groups to protein cross-linking depend on the methylglyoxal concentration. The product formed in the reaction of thiol and an insufficient quantity of methylglyoxal (compared to the concentrations of the groups accessible for modification) participates to a significant extent (4%) to protein cross-linking. Metformin applied in equimolar concentration with methylglyoxal prevents its reaction with amino and guanidino groups but, however, not with thiol groups.Metilglioksal je veoma reaktivni α-oksoaldehid koji se povećano stvara u hiperglikemiji. Reaguje sa nukleofilnim grupama bočnih ostataka Lys, Arg i N-terminalnom amino-grupom, što dovodi do modifikacije proteina. U ovom radu ispitivani su značaj reakcije SH grupe sa metilglioksalom u modifikaciji proteina, konkurentnost ove reakcije u odnosu na reakcije sa amino- i gvanidino-grupom, tok ovih reakcija i njihova uloga i doprinos u umrežavanju proteina. Kao model-sistemi upotrebljeni su humani i goveđi serum-albumin. Utvrđeno je da i pored veoma male zastupljenosti SH grupe na površini ispitivanih molekula proteina (oko 80 puta manja u odnosu na ukupan broj amino- i gvanidino-grupa), ona reaguje u velikom procentu (od 25-85 %). Količina izreagovanih SH grupa i brzina reakcije, vreme uspostavljanja ravnoteže reakcije, stvaranja stabilnog proizvoda i doprinos SH grupa umrežavanju proteina zavise od koncentracije metilglioksala. Proizvod stvoren u reakciji SH grupa i nedovoljne količine metilglioksala (u odnosu na koncentraciju grupa dostupnih za modifikaciju) učestvuje u umrežavanju proteina sa značajnim udelom (4 %). U ekvimolarnoj koncentraciji sa metilglioksalom metformin sprečava njegovu reakciju sa amino i guanidino grupama albumina, ali ne i sa tiol grupom

Vrednosti osnovnih hematoloških parametara u perifernoj krvi radnika izloženih uticaju para žive

In the present study was assessed the influence of occupational exposure to mercury vapours on the basic haematological parameters (erythrocyte, leukocyte and platelet count, haemoglobin concentration, haematocrit, MCV, MCH and MCHC). Studies were carried out on 138 workers involved in the production of chlorine using the mercuric electrolysis method (divided into three groups: permanently, periodically and earlier exposed to mercury vapours), as well as on 38 healthy workers. The shift time - weighted averages for mercury was determined in the workplace air before research; mean value was significantly over maximum tolerated dose. The mercury content in the blood and urine of exposed workers was determined by atomic absorption spectrophotometry. In all three groups 95th percentile values of mercury in blood and urine are significantly over MTD. Peripheral blood cell parameters were determined using an automatic cell counter. In the group exposed to mercury vapours, was found a statistically significant increase of erythrocyte count with a concomitant decrease in MCV. The mean values of haemoglobin concentration, MCHC and platelet count were higher in the group of workers exposed to mercury vapours, but the difference was not statistically significant. There were no significant differences in haematocrit, MCH and leukocytes between the studied groups. Our results indicate that long-term and permanent exposure to mercury vapours induces changes in the important haematological parameters of the peripheral blood.U radu je ispitivan uticaj izloženosti parama žive iz radne sredine na osnovne hematološke parametre (broj eritrocita, leukocita i trombocita, koncentraciju hemoglobina, hematokrit, MCV, MCH i MCHC). U studiju je uključeno 138 radnika koji rade u proizvodnji hlora procesom elektrolize (podeljeni su u tri grupe: stalno izloženi, povremeno izloženi i ranije izloženi uticajima para žive), kao 38 zdravih radnika. Pre studije su određene koncentracije žive u vazduhu radne sredine; srednje vrednosti su bile znatno iznad maksimalne doze tolerancije (MTD). Koncentracije žive u krvi i urinu radnika koji su izloženi živi određena je atomskom apsorpcionom spektrometrijom. U sve tri grupe je vrednost 95-tog percentila bila znatno iznad MTD. Hematološki parametri su određeni uz pomoć automatskog brojača. U grupi koja je stalno izložena parama žive, dobijeno je značajno poveć anje srednje vrednosti broja eritrocita, kao i značajno smanjenje vrednosti MCV. Srednje vrednosti koncentracije hemoglobina, MCHC i broja trombocita u grupi radnika koji su stalno izloženi uticaju žive bile su viće nego u kontrolnoj grupi, ali ta razlika nije statistički značajna. Između posmatranih grupa nije bilo značajne razlike u vrednostima hematokrita, MCH i broja leukocita. Dobijeni rezultati pokazuju da dugotrajna i stalna izloženost parama žive može da dovede do promena u vrednostima važnih hematoloških parametara

Takmičenja iz hemije u periodu od 1984. do 2004. godine - II deo

Development of chemistry competitions for the higher grades of elementary, and for the secondary scholars in former Yugoslavia, and particularly Serbia, within the action 'Science to the Young' in the period 1964-1984 (part I) were described in the Chemical Review 45/3 (2004). In the present text (part II) the development of chemistry competitions for the elementary and secondary scholars in the period 1984-2004 was presented.U Hemijskom pregledu br. 3 (2004) prikazan je razvoj takmičenja iz hemije u okviru Pokreta 'Nauku mladima' u periodu od 1964. do 1984. godine (deo I). U ovom članku prikazan je razvoj i propozicije takmičenja iz hemije u periodu od 1984. do 2004. godine (II deo)

Enzimska kinetička metoda za određivanje propranolol-hidrohlorida u farmaceutskim preparatima zasnovana na njegovom inhibitorskom delovanju na holinesterazu

Propranolol, a widely used beta-blocker, inhibits the hydrolysis reaction of enzyme cholinesterase. Measurements of the difference in rate of hydrolysis rate between uninhibited and inhibited reactions allow the development of a kinetic method for its determination. Both systems, enzyme-substrate-chromogen and enzyme-substrate-chromogen-inhibitor, were characterized through biochemical kinetic parameters (K-M, 0.326-0.330 mmol/L; V-max, 40.0-43.0 mu mol/Lmin). The inhibition type was recognized as competitive and the inhibition constant, Ki, was determined to be 22.60 mu mol/L. The detection and quantification limits were calculated as 0.004 and 0.0136 mu mol/L, respectively. Accuracy and precision of proposed methods were tested. The proposed method showed good sensitivity, selectivity, simplicity and rapidity, thus it is convenient for clinical applications.Za propranolol, često propisivani neselektivni beta blokator, utvrđeno je da inhibira reakciju enzimske hidrolize butiriltioholin-jodida, koja je katalizovana serumskom holinesterazom. Merenjem razlike u brzini osnovne i inhibitorske reakcije hidrolize u prisustvu propranolola kao inhibitora, moguće je razviti kinetičku metodu za određivanje propranolola. Oba sistema, enzim-supstrat-hromogen kao i enzim-supstrat-hromogen-inhibitor, okarakterisani su biohemijskim kinetičkim parametrima (KM, 0,326-0,330 mmol/L; Vmax, 40-42,99 μmol/L min), inhibicija je definisana kao kompetitivna i određena je konstanta inhibicije 22,60 μmol/L. Da bi se u potpunosti iskoristile sve mogućnosti predložene metode u pogledu osetljivosti, tačnosti, preciznosti i selektivnosti, optimizovani su reakcioni uslovi. Konstruisana je kalibraciona prava, izračunata odgovarajuća jednačina i određeni granica detekcije i kvantifikacije i to 0,004 i 0,0136 μmol/L, redom. Tačnost i preciznost predložene metode su ispitane za tri koncentracije propranolola u oblasti kalibracione prave (0,082-21,120 μmol/L) u pet ponavljanja. Takođe, ispitan je uticaj većeg broja supstanci koje se mogu naći u uzorku na brzinu reakcije. Optimizovana metoda je primenjena za određivanje propranolola u farmaceutskim preparatima. Tačnost predložene metode je ispitana primenom metode standardnog dodatka. Predložena metoda ima dobru osetljivost, selektivnost, jednostavna je i brza, i nadasve lako dostupna, i na taj način primenljiva u velikom broju laboratorija

"It happened, what's the problem?" and "A guide through the problem" - A model for consideration of ecological issues in chemistry education

In order to improve the ability to apply knowledge of chemistry (acquired in the existing educational system) in real life, the model for consideration of ecological issues was developed and applied in high school. The model consists of a continuous text "It Happened, What's the Problem?" and a test with non-continuous text "A Guide Through the Problem", which were prepared for consideration of the problem of eutrophication. All results obtained (average achievement of 70.9 +/- 14.3 %) showed that the application of the model enabled: understanding of an ecological problem based on scientific representations of the term eutrophication given in the continuous text, realization that pollution of the environment may be directly related to modern life, application of acquired knowledge of chemistry to observe and understand the cause and effect of eutrophication in the environment, to draw a scientific conclusion, and understanding the importance of science and technology discoveries for solving ecological problems. In addition, the model contributed to the development of student's environmental literacy (ecological knowledge and cognitive skills), ability to think critically, and provided possibilities for classroom knowledge to become applicable in real life

Supplementary data for the article: Vitorović-Todorović, M. D.; Koukoulitsa, C.; Juranić, I. O.; Mandić, L. M.; Drakulić, B. J. Structural Modifications of 4-Aryl-4-Oxo-2-Aminylbutanamides and Their Acetyl- and Butyrylcholinesterase Inhibitory Activity. Investigation of AChE-Ligand Interactions by Docking Calculations and Molecular Dynamics Simulations. European Journal of Medicinal Chemistry 2014, 81, 158–175. https://doi.org/10.1016/j.ejmech.2014.05.008

Supplementary material for: [https://doi.org/10.1016/j.ejmech.2014.05.008]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1808]Related to accepted version:[http://cherry.chem.bg.ac.rs/handle/123456789/2907

How the sialylation level of serum N-acetyl-beta-D-glucosaminidase A form in Type 1 diabetes mellitus influences their activity?

It was verified that the serum N-acetyl-beta-D-glucosaminidase (NAG) activity is elevated in diabetes, but there are no reports about changes in the sialic acid (SA) content in the carbohydrate parts of the NAG A form and its influence on the total changes in NAG activity in type 1 diabetes mellitus patients with and without secondary complications. The NAG A form was isolated from the serum of 81 insulin-dependent diabetes mellitus (IDDM) patients with and without secondary complications (retinopathy, polyneuropathy and nephropathy) and 25 healthy persons, and purified and characterised. The content of alpha-2,6-bound SA, the isoenzyme patterns of the purified A form, and the total NAG and A form activities were determined. In all diabetic groups, the sialylation levels of the A form were 2-3.5 times lower compared to control, while their acidities (fractions with pI 4.25-5.1) increased, particularly with progression of secondary complications. Total serum NAG activities and percentages of A form were significantly higher (P lt 0.001) in all diabetic groups and negatively correlated with the alpha-2,6-bound SA content of the A form. In addition, they decreased as secondary diabetic complications became more complex. The observed changes could be the consequence of structural changes in the A form due to significant increases in its acidity, i.e., negative charge, which originated from groups other than SA

HSA carbonylation with methylglyoxal and the binding/release of copper(II) ions

The potential of carbonylation with methylglyoxal to alter HSA's binding affinity for copper(II) ions and its influence on the release of copper(II) ions from copper-HSA complexes were studied. The affinity of HSA to coordinate copper(II) decreased upon carbonylation of the Cys34-SH group. Carbonylation of copper-HSA complexes caused a decrease in Cys34-SH content, conformational changes and the release of copper(II) ions. The ratio between the percentage of reduction in the Cys34-SH group content and the percentage of release of copper(II) from complexes is 2.12 +/- 0.28. Because the same ratio (1.96 +/- 0.36) was obtained upon oxidation of the Cys34-SH group (with no changes in HSA conformation), the binding/release of copper (II) by HSA depended mainly on the redox state of the Cys34-SH group. The contents of Cys34-SH and HSA-bound copper(II) ions in the diabetic group (0.457 +/- 0.081 mol SH per mol HSA, 10.7 +/- 0.01 mmol per mol HSA, resp.) were significantly lower (p lt 0.01) compared to the control group (0.609 +/- 0.027 mol SH per mol HSA; 13.4 +/- 0.01 mmol per mol HSA, resp.). Very strong correlations between the values for HSA-SH and glycated haemoglobin, HbA1c, (R = -0.803, p lt 0.01), and between the values for the HSA-bound copper(II) content and HSA-SH content (R = 0.841, p lt 0.002) were found in the diabetic group. Thus, HSA carbonylation leads to decrease in HSA-SH content and to the impairment of its copper(II) binding capacity that could contribute to further enhancement of oxidative and carbonyl stress in diabetes (as well as in other diseases with carbonyl stress)

Zastupljenost n-3 polinezasićenih masnih kiselina u fosfolipidima eritrocita i insulinska senzitivnost kod gojaznih osoba pri tipičnoj ishrani podneblja Srbije

This study examines the relationship between erythrocyte phospholipid FA composition and insulin sensitiv­ity in obese patients on a typical Serbian diet. In 30 patients, two insulin sensitivity groups were formed and their FAs analyzed. The shares of 22:5n-3, 22:6n-3, and total n-3 PUFAs, as well as a measure of Δ5 desaturase activity (the 20:4n-6/20:3n-6 ratio) were lower in the insulin resistance group compared to the normal glucose tolerance group. The fasting insulin level and HOMA value were inversely related to the percentage of 22:5n-3, 22:6n-3, and total n-3 PUFAs. Our data indicate that the percentage of n-3 PUFAs in erythrocyte phospholipids is linked with insulin sensitivity parameters in obese patients.Masnokiselinski sastav membrana, koji se bar delimično može modifikovati dijetarnim unosom masnih kiselina, igra važnu ulogu u senzitivnosti na insulin. Cilj ove studije bio je ispitivanje veze između senzitivnosti na insulin i masnokiselinskog sastava fosfolipida eritrocita kod gojaznih osoba. Trideset umereno gojaznih/gojaznih nedijabetičara sa hiperlipoproteinemijama (ukupni holesterol gt 5.2 mmol/l, LDL-holesterol gt 3.4 mmol/l) podeljeni su u dve grupe, koristeći HOMA vrednost kao parametar senzitivnosti na insulin: grupu sa normalnom tolerancom na glukozu (NTG) i grupu sa rezistencijom na insulin (IR). Ukupni lipidi eritrocita su estrahovani i fosfolipidi izolovani tankoslojnom hromatografijom. Posle metilovanja masne kiseline analizirane su gasno-tečnom hromatografijom. Zastupljenost 22:5n-3 (p lt 0.01), 22:6n-3 (p lt 0.01), ukupnih n-3 polinezasićenih masnih kiselina (p lt 0.001) i odnos zastupljenosti 20:4n-6/20:3n-6 (pokazatelja aktivnosti delta-5 desaturaze) (p lt 0.05) su sniženi u IR grupi u poređenju sa NGT grupom. Nivo insulina natašte i HOMA vrednost inverntno su povezani sa zastupljenošću 22:5n-3 (p lt 0.05), 22:6n-3 (p lt 0.01) i ukupnim n-3 polinezasićenim kiselinama (p lt 0.01). Naši rezultati pokazuju da je nivo n-3 masnih kiselina u fosfolipidima eritrocita povezan sa senzitivnošću na insulin kod gojaznih osoba na ishrani tipičnoj za podneblje Srbije

Supplementary data for the article: Vitorović-Todorović, M. D.; Koukoulitsa, C.; Juranić, I. O.; Mandić, L. M.; Drakulić, B. J. Structural Modifications of 4-Aryl-4-Oxo-2-Aminylbutanamides and Their Acetyl- and Butyrylcholinesterase Inhibitory Activity. Investigation of AChE-Ligand Interactions by Docking Calculations and Molecular Dynamics Simulations. European Journal of Medicinal Chemistry 2014, 81, 158–175. https://doi.org/10.1016/j.ejmech.2014.05.008

Supplementary material for: [https://doi.org/10.1016/j.ejmech.2014.05.008]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1808]Related to accepted version:[http://cherry.chem.bg.ac.rs/handle/123456789/2907