bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the Yeast Mitochondriai Unselective Channel in intact and permeabilized spheroplasts
Authors: Manon Stéphen , Guérin Martine 
Published: July 2007

AbstractThe existence of an activity corresponding to the nucleotide‐induced Yeast Mitochondria Unselective Channel (YMUC2) of isolated mitochondria was investigated in permeabilized and intact spheroplasts of the baker's yeast Yeast Foam. In nystatin‐permeabilized spheroplasts, ATP and GDP‐β‐S induced a decavanadate‐sensitive stimulation of the respiration only under conditions equivalent to those previously reported for isolated mitochondria (low phosphate concentration, presence of a salt). On intact spheroplasts, parallel measurements of respiration rate, [ATP]/[ADP] ratio and mitochondrial transmembrane potential allowed to show that the addition of the glucose analog 2‐deoxyglucose decreased the permeability of the inner mitochondrial membrane owing to cellular ATP depletion. This strongly supports the hypothesis that Yeast Mitochondria Unspecific Channel is active in situ and inhibited by cellular [ATP] depletion.
Absorption and fluorescence spectra of polyene antibiotics in the presence of human serum albumin
Authors: Romanini Diana , Farruggia Beatriz , Picó Guillermo 
Published: July 2007

AbstractThe alteration in the fluorescence spectra observed for the polyene antibiotics: nystatin and amphotericin B in the presence of human serum albumin is due to a decrease in the polar character of the antibiotic environment when these are bound to the protein. Amphotericin B showed two types of binding sites, the first having very high affinity (5.8 107 M‐1) and a secondary binding site with an affinity one order lower than the primary sites. This secondary binding site was very sensitive to temperature change. Nystatin yielded only one type of binding sites with an affinity of 1.1 106 M‐1. An electrostatic component was found in the binding of both ligands, as well as an important disorder at the protein binding sites. However the secondary binding site for AMP showed negative entropie change value, which suggests different mechanim of binding respect to the primary one. Conformational change induced by the temperature in the albumin molecule was detected by nystatin binding. Fatty acids produced an interference in the binding of both antibiotics to albumin.
Genetic variants of chicken erythrocyte histone H5
Authors: Górnicka‐Michalska Ewa , Pałyga Jan , Lubon Henryk , Kowalski Andrzej , Cywa‐Benko Katarzyna 
Published: July 2007

AbstractTwo allelic electromorphs a and b of chicken eryhrocyte histone H5 have been detected in a sodium dodecyl sulfate polyacrylamide gel. In an acid‐urea gel, however, each of the allelic variants was found to be accompanied by a slower migrating form. A comparison of α‐chymotrypsin‐digested products of H5.a and H5.b revealed that they differed in N‐terminal domains. The H5 variants were distributed differently not only in various chicken races but also in distinct lines within a breed. Allele H5b was about 2.6‐4.6 as abundant as its counterpart H5a in most chicken populations examined. These proportions were distorted in two Leghorn lines: the ratio of H5b to H5a was only 1.6 in line H22 and increased up to 32 in line G99.
Esterification of D‐mannoheptulose confers to the heptose inhibitory action on D‐glucose metabolism in parotid cells
Authors: Malaisse Willy J. , Kadiata Marcel M. , Scruel Olivier , Sener Abdullah 
Published: July 2007

AbstractD‐mannoheptutose, but not its hexaacetate ester, inhibits, in a competitive manner, D‐glucose phosphorylation by either purified beef heart hexokinase or crude parotid gland homogenates. Yet, D‐mannoheptulose hexaacetate, but neither the unesterified heptose nor acetate or its methyl ester, inhibits D‐[5‐3H]glucose utilization and D‐[U‐14C]glucose conversion to 14CO2 and 14C‐labelled acidic metabolites aud anaino acids in intact isolated parotid cells. It is proposed, therefore, that D‐mannoheptulose hexaacetate crosses efficiently the plasma membrane of parotid cells and, after intracellular hydrolysis, allows inhibition of D‐glucose phosphorylation by the unesterified heptose. The ester of D‐mannoheptulose could thus represent a useful tool to inhibit hexose phosphorylation and interfere with cell growth in cells otherwise resistant to the heptose.
Hepatic heterogeneity in the response to AMP studied in the bivascularly perfused rat liver
Authors: Minguetti‐Câmara Vania Cibele , Constantin Jorgete , Suzuki‐Kemmelmeier Fumie , Bracht Adelar 
Published: July 2007

AbstractThe zonation of the purinergic action of AMP in the hepatic parenchyma was investigated in the bivascularly perfused rat liver by means of anterograde and retrograde perfusion. Livers from fed rats were used and AMP (100 μM) was infused according to four different experimental protocols: (A) anterograde perfusion and AMP infusion via the portal vein; (B) anterograde perfusion and AMP infusion via the hepatic artery; (C) retrograde perfusion and AMP via the hepatic vein; (D) retrograde perfusion and AMP via the hepatic artery. The response of the liver cells was heterogeneous. Oxygen uptake inhibition by AMP predominates in cells situated shortly after the intrasinusoidal confluence of the portal vein and hepatic artery. Oxygen consumption in all other cells seems to be increased by AMP. Glycogenolysis stimulation by AMP (glucose release) was more pronounced in the periportal cells situated in the region of the intrasinusoidal confluence of the portal vein and the hepatic artery. It can be concluded that the heterogenic response of the liver to AMP is similar to the heterogenic response to ATP.
Effect of salts on the interaction of oxidized glutathione with dibasic amino acids
Authors: Cserháti Tibor 
Published: July 2007

AbstractThe interaction of oxidized glutathione (GSSG) with dibasic amino acids was studied with charge‐transfer chromatography carried out on unimpregnated cellulose layers in the absence and presence of LiCl, NaCl, KCl, MgCl2 and CaCl2. GSSG decreased in each case the apparent lipophilicity of dibasic amino acids, indicating some type of interaction. Calculations proved that the strength of GSSG ‐ dibasic amino acid interaction decreases with increasing concentration of salts suggesting a hydrophilic character of interaction. It can be assumed that electrostatic forces between the carboxyl group of GSSG and the amino groups of amino acids are involved in the interaction. GSSG binds stronger to arginine than to lysine and ornithine suggesting that arginine is probably the primary binding site in proteins for GSSG.
Fatty acid‐mediated uncoupling of potato tuber mitochondria
Authors: Saviani Elzira E. , Martins Ione S. 
Published: July 2007

AbstractThe present work examined whether the ATP/ADP carrier, other than the plant uncoupling mitochondrial protein, participates in free fatty acid‐mediated uncoupling of potato tuber mitochondria. The basal respiration rate of succinate‐energized mitochondria was stimulated by a low concentration of palmitate (20μM). This uncoupling was reversed by 10μM carboxyatractyloside and by the subsequent addition of 0.1% bovine serum albumin. The decrease in membrane potential caused by palmitate was suppressed by carboxyatractyloside (1μM) and, to a lesser degree, by bongkrekate (20μM). GTP could also reversed this decrease via a carboxyatractyloside‐independent mechanism. These results indicate that the ATP/ADP carrier, along with the plant uncoupling mitochondrial protein, participates in the protonophoric action of palmitate in potato tuber mitochondria.
The interaction of alcohol peroxyl radicals with human oxyhemoglobin
Authors: Szweda‐Lewandowska Z. , Krokosz A. , Zajaczkowska W. , Puchaŀa M. 
Published: July 2007

AbstractThe effects of interaction of ethanol, l‐butanol or t‐butanol peroxyl radicals with oxyhemoglobin (HbO2) were estimated using absorption spectroscopy in the visible range and tryptophan fluorescence. Peroxyl radicals were generated by gamma‐radiation. Alcohol peroxyl radicals showed the same effectiveness in oxidizing HbO2 iron as ‐OH radicals (GFe(III) = 1.8 for a dose 0.33 kGy). However, they degraded hemoglobin to hemichromes and cholehemichromes to a lesser degree than ‐OH radicals. In addition l‐ and t‐butanol peroxyl radicals were less effective than peroxyl ethanol radicals. Alcohol peroxyl radicals caused unfolding of protein to a much lesser degree than ‐OH radicals. Their contribution to the destruction of tryptophan residues was nearly matched by those obtained with the ‐OH radicals.
Synthesis of a unique polysialoganglioside by polysialyltranfferase from embryos of sea urchin Lytechnius pictus: Size determination of polysialic acid chain synthesized onto GD3 in vitro
Authors: Cho Jin Won 
Published: July 2007

AbstractIt has been reported that polysialyltransferase in sea urchin embryos polysialylates 38 kDa endogenous acceptor proteins and disialyllactose moieties of mammalian ganglioside GD3, and its maximum activity was observed at gastrula stage using an excess of GD3 as an exogenous acceptor (1). The objective of the present investigation is to determine how many sialic acid residues are transferred onto the disialyllactose moiety of GD3 by the polysialyltransferase when it is used as an exogenous acceptor. Ceramide glycanase which can cleave the linkage between ceramide and sugar moiety was treated to obtain hydrophilic polysialyllactose from polysialylated GD3. Surprisingly, size analysis of these chains using non‐SDS polyacrylamide gel electrophoresis showed that up to 60 sialic acid residues were transferred to the disialyllactose moiety of GD3 by polysiatyltransferase from the sea urchin embryos.
Human DNA‐topoisomerase I activity is affected by bis‐netropsin's binding to DNA minor groove
Authors: Sukhanova Alyona , Grokhovsky Sergei , Zhuze Alexei , Roper David , Bronstein Igor 
Published: July 2007

AbstractBis‐netropsins (bis‐Nts) are known to be efficient inhibitors of human DNA topoisomerase (topo) I with a higher antitumor activity than netropsin. New sequence‐specific derivatives of bis‐Nts were used for modulation of topo I‐mediated DNA cleavage with and without camptothecin (CPT). Relation between the bis‐Nts binding sites and topo I cleavage sites has been analyzed with the plasmid DNA constructs generated by insertion of synthetic oligonucleotides containing various topo I‐cleavage and bis‐Nt‐binding sites. These constructs offer an opportunity to study minor groove binders effects on the topo I reaction on DNA. Three major effects: (i) bis‐Nt ‐ mediated disappearance of some of the topo I cleavage sites; (ii) enhancement of some other sites, and, (iii) generation of new cleavage sites, have been fovnd and analyzed. These effects demonstrate that bis‐Nts drastically change the topo I‐mediated DNA cleavage.
Cloning and sequence analysis of novel cardiotoxins/CLBP from venom glands of Jaja naja atra
Authors: Chu Ren‐Chian , Yang C. C. 
Published: July 2007

AbstractSeventeen cardiotoxins (CTXs)3 and four CLBPs3 have been identified by screening cDNA library and in conjunction with the PCR approach. Among the 17 CTXs, two have silent substitutions, five have previously been identified by traditional protein sequencing methods. In addition, ten not well known CTX genes and one new CLBP have been identified. These CTX genes show very high sequence homology with the major variations occurring at the tip of each individual loop. Although the CTX isoforms differ by only one or few residues and this subtle differences strongly influences the structure and function of the CTX isoforms. We have identified a novel CTX‐3c sequence which represents a blend of the CTX‐1 and CTX‐3 sequence. Based on the sequence comparison with other CTX isoforms from the same snake source, we predict interesting functional properties for CTX‐3c.
The interaction of phospholipase A2 with liposomes: An immunological approach to its study
Authors: Morales Rogelio , Zavala Eunice , Fernández Marta S. 
Published: July 2007

AbstractPorcine pancreatic phospholipase A2 (PLA2) has been incubated for 2 hours at 34°C with rabbit anti‐pig pancreatic PLA2 polyclonal antiserum in the absence or presence of phosphatidylcholine liposomes in different physical states. Subsequent assay of hydrolysis ‐triggered through addition of 5 mM Ca2+‐ at 34°C, shows that preincubation with antiserum in the presence of 1,2‐dimyristoyl‐3‐sn‐phosphatidylcholine liquid‐crystalline vesicles, renders the PLA2 activity undetectable, similarly to what is found if preincubation is carried out in the absence of liposomes. In contrast, 1,2‐dipalmitoyl‐3‐sn‐phosphatidylcholine liposomes, which at 34°C are in the gel‐phase, protect the enzyme from the antiserum effect. The results are consistent with a stronger binding of PLA2 to gel phase, as compared to liquid crystalline vesicles and suggest that through the physical interaction with liposomes in the gel state, the enzyme is shielded from reaction with the antibodies. Taking into account the characteristic hydrolysis profiles of vesicles in different physical states, it can be concluded that the above interpretation agrees with the proposal that PLA2‐membrane association promotes the interfacial activation of the enzyme.
Molecular cloning and regulation of a novel guinea pig cytochrome P450 (CYP3A20) which differs from guinea pig CYP3A14 in only two amino acid residues
Authors: Mori Toshiyuki , Itoh Susumu , Kamataki Tetsuya 
Published: July 2007

AbstractA full length cDNA clone of cytochrome P450, encoding 503 amino acid residues, was isolated from a male guinea pig liver cDNA library. The sequence was highly homologous to other members in the CYP3A subfamily and was designated CYP3A20. CYP3A20 and CYP3A14, another guinea pig CYP3A, shared 99.4% nucleotide and 99.6% deduced amino acid sequence homology. There were only two amino acid differences between CYP3A20 and CYP3A14. No significant induction of CYP3A20 mRNA in the livers from male guinea pigs treated with dexamethasone was observed by S1 mapping analysis although CYP3A14 mRNA was induced. The expression of CYP3A20 mRNA in the livers did not change between 5 and 10 weeks after birth while that of CYP3A14 mRNA in livers significantly increased at 10 weeks. This is the first report that the two highly resembling forms of cytochrome P450 display differently regulated expression from each other.
Characterisation of L‐[3H]glutamate binding to fresh and frozen crude plasma membranes isolated from cerebral cortex of adult rats
Authors: Emanuelli T. , Antunes V. F. , Souza D. O. G. 
Published: July 2007

AbstractSpecific [3H]glutamate binding to fresh crude plasma membranes (CPMs) was compared with binding to frozen CPMs and the optimal conditions for the binding to frozen CPMs isolated from cerebral cortex of adult rats were determined. Freezing reduced [3H]glutamate binding (3.5‐fold), and pre‐incubation of previously frozen membranes followed by three washes increased binding (4.5‐fold) when compared to fresh samples. CPMs washed once, pre‐incubated at 37°C and washed 3 times was adopted as the most adequate condition for the binding assay of frozen membranes. In a Cl‐‐containing medium, [3H]glutamate binding (Bmax=97.9 pmol/mg, Kd=349.68 nM) to this frozen CPM preparation was significantly displaced by excess quisqualic acid (QA) (65%), L‐2‐amino‐4‐phosphonobutyric acid (L‐AP4) (35%), trans‐1‐aminocyclopentane‐1,3‐dicarboxylate (1S,3R‐ACPD) (25%) and alfa‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA) (25%). In a Cl‐‐free medium, binding (Bmax=44.14 pmol/mg, 311 nM) was significantly displaced by QA (45%), L‐AP4 (25%), ACPD (25%), AMPA (25%), kainic acid (20%) and N‐methyl‐D‐aspartate (15%).
Thyroid hormone, all‐trans retinoic acid, and 9‐cis retinoic acid functioned as negative modulators of the effect of glucocorticoid on induction of α1‐acid glycoprotein mRNA in RLN‐10 cells
Authors: Li Xiaoman , Sumi Tomoyuki , Matsukawa Toru , Nakanishi Yoshinobu , Ohba Yoshiki 
Published: July 2007

AbstractThe expression of acute‐phase protein genes is controlled by many factors, such as IL‐1, IL‐6, glucocorticoids, thyroid hormone (T3), and retinoic acids. We studied the interaction of T3, glucocorticoids, all‐trans retinoic acid (RA), and 9‐cis retinoic acid (9cRA) on the expression of the rat α1‐acid glycoprotein (AGP) gene in vitro. Dexamethasonc (Dex) activated AGP gene expression in a rat liver derived cell line, RLN‐10. Although T3, RA, and 9cRA by themselves had no effect on AGP production, they reduced the response to Dex of the AGP gene.
Influence of phenoxyherbicides and their metabolities on the form of oxy‐and deoxyhemoglobin of vertebrates
Authors: Bukowska Bozena , Reszka Edyta , Duda Wirgiliusz 
Published: July 2007

AbstractThe effect of phenoxyherbicides and their metabolites on the structure of oxy‐ and deoxyhemoglobin was studied by using different doses and times of incubation of hemoglobin with the herbicide. It was ascertained that among the investigated hemoglobins the most sensitive was carp oxyhemoglobin incubated with 2,4‐D (2,4‐dichlorophenoxyacetic acid) and the least sensitive was human hemoglobin. Comparing the toxicity of 2,4‐D, MCPA (2‐methyl‐4‐chlorophenoxyacetic acid), 2,4‐DCP (2,4‐dichlorophenol), 2,4‐DMP (2,4‐dimethylphenol) it was found that the highest decrease occurred in bovine hemoglobin incubated with 2,4‐DMP. The phenoxyherbicides caused stabilization of the structure of T‐deoxyhemoglobin in vitro, in that they decreased the oxygen affinity with a simultaneous increase in methemoglobin concentration.
Reactivity of the horseradish peroxidase compounds I and II toward organometallic substrates. A stopped‐flow kinetic study of oxidation of ferrocenes
Authors: Goral Vasily N. , Ryabov Alexander D. 
Published: July 2007

AbstractReactivity of horseradish peroxidase compounds I and II (HRP‐I and HRP‐II) toward organometallicic substrates, viz water‐soluble ferrocenes RFc (R = COOH and CH2NMe2), has been studied at 25 °C, pH 6.0 and ionic strength 0.1 M. The second‐order rate constants k2 for the reaction of HRP‐I with FcCOOH and FcCH2NMe2 equal (1.00±0.04)×106 and (0.27±0.01)×106 M‐1 s‐1, respectively. The values of k3 for the reaction of HRP‐II with FcCOOH and FcCH2NMe2 equal (1.1±0.1)×l04 and (0.25±0.01)×104 M‐1 s‐1, respectively. The steady‐state kinetic study of the HRP‐catalyzed oxidation of the ferroeenes by H202 under the same conditions gave the second‐order rate constants of (0.94±0.03)×104 and (0.24±0.06)×104 M‐1 s‐1 for FcCOOH and FcCH2NMe2, respectively, which are in a good agreement with k3. The results reported here confirm the proposal that the rate‐limiting step of the steady‐state oxidation of ferrocenes is the electron transfer from the substrate to HRP‐II.
Lucigenin reduction by nadph‐cytochrome P450 reductase and the effect of phospholipids and albumin on chemiluminescence
Authors: Tsukamoto Maki , Tampo Yoshiko , Yonaha Masanori 
Published: July 2007

AbstractTo assess lucigenin, a chemilumigenic probe, as a detector of superoxide anion in microsomes, NADPH oxidation, lucigenin disappearance, and chemiluminescence in a system including purified NADPH‐cytochrome P450 reductase were exmnined. NADPH oxidation was increased by adding lucigenin, and concurrently, its disappearance and oxygen consumption were also stimulated. Chemiluminescence, which is negligibly emitted in the presence of the reductase alone, was remarkably amplified with phospholipids and albumin. Menadione inhibited lucigenin disappearance resulting in suppression of chemiluminescence. Lucigenin chemiluminescence measured in microsomes appears not to reflect direct superoxide anion production from microsomal components and from quinones, such as menadione.
DNA methylation by wheat cytosine DNA methyltransferase: Modulation by protease inhibitor E‐64
Authors: Vlasova Tatyana I. , Vanyushin Boris F. 
Published: July 2007

AbstractCytosine DNA methyltransferase isolated from wheat seedlings and purified in the presence of metalloprotease and serine protease inhibitors has molecular mass and specific activity equal to about 85 kDa and 250 units/mg protein, respectively. Apparent Km for AdoMet& and [I]50 for AdoHcy values are about 6 μM and 12 μM, respectively. The enzyme is active in wide pH range (pH 5.5‐8.5) and is inhibited by NaCl. The enzyme rapidly loses its methyltransferase activity in the absence of substrates. Using the cysteine protease inhibitor E‐64 it has been shown that rapid enzyme inactivation is caused by disappearance of essential enzyme SH‐groups but is not due to proteolytic enzyme cleavage.
Cloning and sequencing of the cDNA coding for pig preuteroglobin/clara cell 10 kDA protein
Authors: Sagal Rubén Gutiérrez , Nieto Antonio 
Published: July 2007

AbstractUsing reverse transcription‐polymerase chain reaction (RT‐PCR) on pig lung mRNAs, we have cloned and sequenced an almost full‐length complementary DNA (cDNA) coding for pig pre‐uteroglobin/Clara cell 10 kDa protein (UG/CC10), a major secretory protein of tung Clara cells. The deduced amino acid sequence indicated a preprotein of 91 residues, 21 of which corresponded to the signal peptide. Comparison of the sequence with those of known pre‐UG/CC10 from other species indicated that the pig protein resembles the structure shared by human and Lagomorpha pre‐UG/CC10 but differ from the proteins from Rodentia that are composed of 96 aminoacids and contain signal peptides of 19 residues. Some amino acids, that form part of a hydrophobic pocket inside the mature protein, are well conserved in all UG/CC10 suggesting an important function of this cavity. Northern analysis indicated that pig UG/CC10 mRNA is abundant in lung but is not detectable in liver, uterus or epididymis. The results are discussed in relation to a possible physiological function of UG/CC10.
Effect of some physiological factors on nitrogenase activity and nitrogenase mediated hydrogen evolution by mixed microbial culture
Authors: Kumar Ashok , Jain Seema R. , Kalia Vipin C. , Joshi Arvind P. 
Published: July 2007

AbstractFermentative H2 evolution, nitrogenase activity (acetylene reduction) and nitrogenase mediated H2 evolution was studied in free cells of mixed microbial population of H2 producers. At 3% glucose level, the cells produced 8.35 1 H2/mol glucose utilized. The role of nitrogenase system in H2 generation was evident by derepressed nitrogenase activity (0.46 nmoles C2H4 produced/mg protein/h) under defined in vitro conditions. For maximum expression of the activity, the cells required preactivation under anaerobic conditions by incubating at 40 °C for 20‐24h with 0.2% glucose in the culture medium. At an O2 level of more than 0.25%, the acetylene reduction activity decreased significantly and could not be detected at a level of 20%. Nitrogenase activity development was higher at acetylene: inoculum ratio between 4.2‐6.25. H2 evolution was lower when the mixed cells were incubated under an atmosphere of 10% C2H2 and 5%CO gas. This decrease in H2 evolution was also evident at 2.5‐6.5 mM NaNO3 and KNO3 concentrations in the liquid culture medium thus establishing more than 50% H2 evolution through nitrogenase.