of-SH Groups Research Articles

Wpływ pola magnetycznego ekstremalnie niskiej częstotliwości na zawartość białka całkowitego oraz grup –SH w homogenatach wątroby

Free radicals are atoms, molecules or their fragments, whose excess leads to the development of oxidative stress, the cause of many neoplastic, neurodegenerative and inflammatory diseases, as well as aging of organisms. Industrial pollution, tobacco smoke, ionizing radiation, ultrasound and magnetic fields are the major exogenous sources of free radicals. The low frequency mag- netic field is commonly applied in physiotherapy. The aim of the present study was to evaluate the effect of extremely low frequency magnetic field (1L.F-MF) on the concentration ofsullhydryl groups (-SH) and proteins in liver tissues of experimental animals de- pending on the time of exposure to the field. Twenty one Sprague-D)awley male rats, aged 3-4 months were randomly divided into 3 experimental groups (each containing 7 animals): controls (group I), the rats exposed to IEI.F-MF of 40 Hz, 7 mT (this kind of the ELF-MF is mostly used in magnetotherapy), 30 min/day for 2 weeks (group II) and the rats exposed to 40 Hz, 7 mT for 60 min/day for 2 weeks (group III). The concentrations of proteins and sulfhydryl groups in the liver tissues were determined after exposure to magnetic fields. Exposure to low magnetic field: 40 Hz, 7 mT for 30 min/day and 60 min/day for 2 weeks caused a significant increase in the concentration of-SH groups and total protein levels in the liver tissues. The study results suggest that exposure to magnetic fields leads to the development of adaptive mechanisms to maintain the balance in the body oxidation-reduction and in the case of the studied parameters does not depend on the time of exposure.

“Short” Dithiol and Au Nanoparticles Grafting on Plasma Treated Polyethyleneterephthalate

Surface of polyethyleneterephthalate (PET) was modified by plasma discharge and subsequently grafted with dithiol (4,4-bifenyldithiol, BFD)) to create thiol (-SH) groups on polymer surface. This short dithiol is expected to be fixed via one of-SH groups to radicals created by the plasma treatment on the PET surface. Free-SH groups are allowed to interact with Au nanoparticles. Xray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and Electrokinetic Analysis (EA, zeta potential) were used for the characterization of surface chemistry of the modified PET. Surface morphology and roughness of the samples were studied by Atomic Force Microscopy (AFM).The results from XPS, FTIR, EA and AFM show that the Au nanoparticles are grafted on modified surface in the case of bifenyldithiol pretreatment. The rigid molecule of biphenyldithiol is bounded via only one-SH group to the modified PET surface and the second one remains free for the consecutive chemical reaction with Au nanoparticle. The gold nanoparticles are distributed relatively homogenously over the polymer surface.

HPLC method for amino acids profile in biological fluids and inborn metabolic disorders of aminoacidopathies

Quantification of total and individual amino acids in biological fluids such as plasma, urine and cerebrospinal fluid has an important diagnostic implication in laboratory medicine. The present paper describes protocols for the assay of total amino acids by modified method based on dinitrophenyl and HPLC profile involving pre-column derivatization with o-pthalaldehyde (OPA) derivatization, respectively. The method, based on the alkylation of-SH groups prior to OPA derivatization of amino acids followed by reverse phase high performance liquid chromatography, provide a comprehensive profile of more than twenty amino acids (including-SH group containing) in a single run lasting about 45 minutes. The present study, apart from establishing the normal profile of amino acids in plasma of Indian sub population, also presents HPLC profile for some of the rare amino acidopathies.

Effect of osmotic stress on protein turnover in Lemna minor fronds

Evidence is presented that although many proteins from the fronds of Lemna minor L. undergo enhanced degradation during osmotic stress, ribulose-1,5-bisphosphate carboxylase (RuBPCase) is not degraded. Instead RuBPCase is converted in a series of steps to a very high-molecular-weight form. The first step involves the induction of an oxidase system which after 24 h of stress converts RuBPCase to an acidic and catalytically inactive form. Subsequently, the oxidised RuBPCase protein is gradually polymerized to a number of very large aggregates (molecular weight of several million).The conversion of RuBPCase to a high-molecular-weight form appears to be correlated with (i) a reduction in the number of-SH residues and (ii) the susceptibility to in-vitro proteolysis. Indeed, the number of-SH groups per RuBPCase molecule decreases from 89 in the native enzyme to 54 and 22 in the oxidised and polymerized forms, respectively. On the other hand, the oxidised enzyme is more susceptible to in-vitro proteolysis than the native form. However, it is the polymerized form of RuBPCase which is particularly susceptible to in-vitro proteolysis.Western-blotting experiments and anti-ubiquitin antibodies were used to detect the presence of ubiquitin conjugates in extracts from osmotically stressed Lemna fronds. The possible involvement of ubiquitin in the formation of the aggregates is discussed.

Conversion of ribulose-1,5-bisphosphate carboxylase to an acidic and catalytically inactive form by extracts of osmotically stressed Lemna minor fronds

The fronds of Lemna minor L. respond to a number of stresses, and in particular to an osmotic stress, by producing an enzyme system which catalyzes the oxidation of ribulose-1,5-bisphosphate carboxylase (RuBPCase; EC 4.1.1.39) to an acidic and catalytically inactive form. During the first 24 h of osmotic stress the induced oxidase system does not seem to exert a significant in-vivo effect on RuBPCase, presumably because of compartmentation. Subsequently, the oxidase system gains access to the enzyme and converts it to the acid and catalytically inactive form and eventually the oxidase system declines in activity.A number of partially acidified forms of RuBPCase are formed during oxidation, and this process appears to be correlated with the disappearance of varying numbers of SH residues. The number of-SH residues in RuBPCase from Lemna has been estimated at 89. However, RuBPCase isolated from 24-h osmotically stressed fronds showed a reduction in the number of-SH residues per molecule from 89 to 54. It seems likely that the oxidation of-SH groups is causally related to the acidification of RuBPCase which occurs during osmotic stress.

Diene Rubber Modification Using Thiol-Type Derivatives

Abstract Thiol-containing antioxidants such as 4-(mercaptoacetamido)-diphenylamine (MADA) undergo ready addition of-SH groups to the double bonds in diene rubbers in the presence of initiators. The reaction is a radical chain process leading to rubbers with improved thermooxidative resistance. The modification reaction has been carried out on high cis-polyisoprene and polybutadiene, and conditions under which the physicochemical properties (e.g., inherent viscosity, gel content, and microstructure) are less affected have been found. An oxygen absorption test and DSC were used as rapid methods for evaluation of thermooxidative stability of modified rubbers. The superiority of rubbers with MADA chemically attached (ranging from 1 to 4 phr) was shown by a circulating air oven test and by an extraction process which simulates the aggressive environments experienced by many rubbers under practical conditions. The results obtained show that a small degree of modification (1 phr MADA) is large enough to provide good thermooxidative stability without alteration of the molecular characteristics of the parent rubbers. At higher degrees, cistrans isomerization can occur.

Electron cytochemical demonstration of -SH groups in the synaptic vesicles of photoreceptor cells with the mixture of zinc iodide-osmium tetroxide.

Se demuestra, en un estudio in vitro, que el ditioeritriol (DTE), agente reductor de grupos -S-S-aumenta, la reactividad de las vesículas sináapticas de las células fotorreceptoras de la rata para la mezcla de yoduro de zinc-tetrozido de osmio (ZIO), a 4°C durante 2 h, mientras que la N-etil-maleimida, bloquenante de grupos-SH, bloquea la reacción en los testigos y en los tratados previamente con DTE. Se concluye que ZIO a 4°C durante 2 h revela grupos -Sh en las vesiculas sinápticas estudiadas.

Histochemical studies on alkaline phosphatases in mineralizing oral tissues in the mouse.

Activity of alkaline phosphatases in unfixed cold microtome setions from the lower first molar area of newborn mice was recorded by histochemical methods. A substrate specificity test included the following phosphate compounds: ATP, CTP, GTP, UTP, ADP, AMP, GP, PPi, MDP and naphthol AS-TR phosphate. Intense staining was obtained in osteoblasts, stratum intermedium of the enamel organ and odontoblasts with all the substrates, except PPi and MDP. Staining of skeletal muscle fibres was obtained only with triphosphates as substrates. Addition of-SH groups decreased the hydrolysis of triphosphate compounds in cells involved in mineralization while the hydrolysis of monophosphate was inhibited. In contrast triphosphatase activity in striated muscle was enhanced when-SH compounds were added. Demineralization with EDTA diminished the cytoplasmic staining but induced a nuclear staining in hard tissue forming cells when triphosphates were used as substrates. No cytoplasmic and only slight nuclear staining was seen with GP or AMP as substrates. The triphosphate hydrolyzing capacity of tongue muscle fibres was, however, increased after the decalcification treatment. Addition of Mg2+ ions to the incubation media distinctly lowered the hydrolysis of triphosphates in the investigated tissues whereas the hydrolysis of ADP, AMP, GP and naphthol AS-TR phosphate remained unchanged. In view of the findings the triphosphatase activities at alkaline pH of muscle fibres and of cells related to hard tissue formation are considered to be due to activity of separate enzymes. The orthophosphate liberating enzyme activities at alkaline pH in osteoblasts, stratum intermedium and odontoblasts may be expressions of the catalytic functions of one common enzyme. Furthermore, the results indicate that CaATP might be the substrate used by the alkaline ATPase in mineralizing areas.

STUDIES ON CYSTINE IN WOOL

1) It wasa found that phospho-tungstic acid (Wo), a reagent for the estimation of-SH groups, could be used as a colour reagent in the paper chromatography for mercapto or disulphide compounds.This reagent causes remarkable colourations on the paperchromatogram in the presence of-SH groups, and also by spraying sodium sulphite solution (Na2 SO3) followeing the Wo-spraying in the presence of -S-S- bonds.This method is profitable for ease of treatment and in sensitivity compared with the nitroprusside-cyanide method. When ninhydrin is used together on the same paper, this must be sprayed after Wo or Wo-Na2 SO3 spraying, otherwise the quantities to be detected of-SH groups or -S-S- bonds decrease in order to react between -SH groups and ninhydrin. In the presence of compound with -SH groups, the mixture of n-butanol, acetic acid and water for the developing solution brings the clear spots on the chromatogram than phenol solution does.2) Based on the above results, reactions between-SH groups and -S-S- bonds were further studied. Mixed disulphide (CY-S-S-TG) was, even without being oxidized by iodine, detected from the mixed solution of cysteine (CY-SH) and thioglycollic acid (TG-SH) which was kept at comparatively higher pH. In the same way, this compound was detected from the mixed solution of cystine (CY-S.) with TC-SH, and of CY SY. with dithiodiglicollic acid (TG-S-S-TG) respectively except at very low pH.The preciser result was obtained by means of combining those mixtures with dinitroflorobenzen, known as-SH blocking agent.Neither TG-SH nor TG-S-S-TGspot was detected when TG-SH solution was mixed with diazonium salt of sulphanilic acid. Two Wo-possitive spots which have lower Rf's than that of TG-SH were recognized in addition to TG-S-S-TG when TG-SH solution was mixed with sodium nitrite on acidic side.This method could also be applied to find sulphur compounds in the hydrolyzates of wool.

STUDIES ON CYSTINE IN WOOL

1) It wasa found that phospho-tungstic acid (Wo), a reagent for the estimation of-SH groups, could be used as a colour reagent in the paper chromatography for mercapto or disulphide compounds.This reagent causes remarkable colourations on the paperchromatogram in the presence of-SH groups, and also by spraying sodium sulphite solution (Na2 SO3) followeing the Wo-spraying in the presence of -S-S- bonds.This method is profitable for ease of treatment and in sensitivity compared with the nitroprusside-cyanide method. When ninhydrin is used together on the same paper, this must be sprayed after Wo or Wo-Na2 SO3 spraying, otherwise the quantities to be detected of-SH groups or -S-S- bonds decrease in order to react between -SH groups and ninhydrin. In the presence of compound with -SH groups, the mixture of n-butanol, acetic acid and water for the developing solution brings the clear spots on the chromatogram than phenol solution does.2) Based on the above results, reactions between-SH groups and -S-S- bonds were further studied. Mixed disulphide (CY-S-S-TG) was, even without being oxidized by iodine, detected from the mixed solution of cysteine (CY-SH) and thioglycollic acid (TG-SH) which was kept at comparatively higher pH. In the same way, this compound was detected from the mixed solution of cystine (CY-S.) with TC-SH, and of CY SY. with dithiodiglicollic acid (TG-S-S-TG) respectively except at very low pH.The preciser result was obtained by means of combining those mixtures with dinitroflorobenzen, known as-SH blocking agent.Neither TG-SH nor TG-S-S-TGspot was detected when TG-SH solution was mixed with diazonium salt of sulphanilic acid. Two Wo-possitive spots which have lower Rf's than that of TG-SH were recognized in addition to TG-S-S-TG when TG-SH solution was mixed with sodium nitrite on acidic side.This method could also be applied to find sulphur compounds in the hydrolyzates of wool.