bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protoporphyrin IX potentiates horseradish peroxidase‐catalyzed oxidation of NADH:Involvement of enzyme‐porphyrin interaction
Authors: Sil Susmita , Chakraborti Abhay S. 
Published: July 2007

AbstractProtoporphyrin IX potentiates horseradish peroxidase‐catalyzed hydrogen peroxide‐mediated NADH oxidation, but the porphyrin cannot change the enzyme‐catalyzed o‐dianisidine oxidation. Spectrofluorimetric studies reveal that an interaction occurs between horseradish peroxidase and protoporphyrin IX. The interaction is predominantly hydrophobic and entropy‐driven endothermic process. This interaction may influence the potentiation effect of the protoporphyrin IX on horseradish peroxidase‐catalyzed NADH oxidation because the latter has a positive correlation with the extent of binding of the protein with the porphyrin.
NMR characterization of physicochemical properties of rat D‐dopachrome tautomerase
Authors: Yoshida Hitoshi , Nishihira Jun , Suzuki Masaki , Hikichi Kunio 
Published: July 2007

AbstractD‐dopachrome tautomerase (DOPD) catalyzes the conversion of D‐dopachrome to 5,6‐dihydroxyindole. DOPD was found to have amino acid sequence homology with macrophage migration inhibitor factor (MIF), suggesting that DOPD functions as a proinflammatory cytokine. We here demonstrate the physicochemical properties of DOPD by nuclear magnetic resonance (NMR). The native molecular weight of rat DOPD was about 37 kDa as calculated from Sephadex G‐100 column chromatography. Since the deduced molecular weight of its cDNA (117 amino acid residues) is 12.5 kDa, it is assumed that DOPD exists as a homotrimer in native form. Since several methyl proton resonances were observed in the high magnetic field region of the one‐dimensional 1H‐NMR spectrum, DOPD appeared to have a hydrophobic core in which methyl groups and aromatic groups are located close to each other. From a simple integration of one‐dimensional 1H‐NMR spectra, the contents of the α‐helix,β‐strand, and random coil were calculated to be 16%, 68%, and 16%, respectively. Since the denaturation temperature of DOPD is exceedingly high at the range between 90‐100°C, it is considered that the high β‐strand content may contribute to its heat stability.
Involvement of an endogenous metalloprotease in the activation of protoxin in Bacillus thuringiensis subsp. kurstaki
Authors: Kumar N. Suresh , Venkateswerlu G. 
Published: July 2007

AbstractInsecticidal crystal proteins harvested from sporulated cultures of Bacillus thuringiensis subsp, kurstaki contain the protoxin (Mr 132 kDa) and minor amounts of toxin (66 kDa). The proteolytic processing of 132 kDa protoxin to an active 66 kDa toxin is brought about by exogenous proteases or larval gut enzymes. Under denaturing / reducing conditions this conversion is also mediated by endogenous protease(s) of the producer organism. This endogenous protease is identified as a metalloprotease as the activation process is inhibited by ethylenediamine tetraacetic acid at 2 mM concentration.
Free radicals in the cerebrospinal fluid are associated with neurological disorders including mitochondrial encephalomyopathy
Authors: Ihara Yuetsu , Kibata Masayoshi , Hayabara Toshiyuki , Katayama Shizuo , Konishi Hiroshi , Miura Kenzo , Kohno Masahiro , Kawai Motoko , Yokoi Isao , Mori Akitane 
Published: July 2007

AbstractThe free radical levels in the cerebrospinal fluid of 8 patients with neurological diseases and 9 undergoing lumbar anesthesia for surgery were measured. The ascorbate free radical level 10 min after lumbar puncture showed a positive correlation with the hydroxyl radical level. In the patient with mitochondrial encephalomyopathy, the levels of hydroxyl and ascorbate free radicals increased upon discontinuation of treatment and decreased upon its resumption, and the ascorbate free radical levels without therapy fell after lumbar puncture. The free radical levels in the cerebrospinal fluid may reflect the degree of oxidative stress in the central nervous system.
Interaction of bromocresol green with different serum albumins studied by fluorescence quenching
Authors: Trivedu V. D. , Saxena I. , Siddiqui M. U. , Qasim M. A. 
Published: July 2007

AbstractThe binding of bromocresol green to bovine serum albumin at micromolar concentrations leads to quenching of protein fluorescence. This property has been used here to study interaction of bromocresol green with bovine serum albumin as a function of pH and ionic strength. The transformation of fluorescence quench data obtained with bromocresol green into Scatchard plots yielded an association constant of 3.06×107 1M‐1 and a binding capacity of about 1.0. The affinity of bromocresol green for bovine serum albumin remains virtually unchanged between pH 4.0 and 8.0 but decreases by about 7 fold with increase in ionic strength from 0.01 to 1.0. Six other serum albumins obtained from cat, dog, human, pig and sheep have also been studied for bromocresol green binding. Although all the albumins studied bind bromocresol green, they show considerable differences in their affinities towards the dye. It appears that despite a great degree of overall similarity in their structure and conformation, serum albumins from different species differ in their ligand binding properties.
Thapsigargin induces apoptosis in SH‐SY5Y neuroblastoma cells and cerebrocortical cultures
Authors: Nath Rathna , Raser Kadee J. , Hajimohammadreza Iradj , Wang Kevin K. W. 
Published: July 2007

AbstractThapsigargin, a specific inhibitor of the endoplasmic reticular Ca2+‐ATPase, has been used previously to mobilize calcium release from intracellular calcium stores. We now show that thapsigargin (1‐10 μM) induces apoptosis in a neuroblastoma cell line (SH‐SY5Y) and in fetal rat cerebrocortical cultures. Cell death measured by lactate dehydrogenase release was observed 24‐48 hours after treatment with thapsigargin. In both cases, DNA extracts from thapsigargin treated cells showed laddering, typical of endonuclease‐mediated internucleosomal cleavages. The presence of DNA fragments was also confirmed by an ELISA designed for detecting nucleosomes in apoptotic cells. Cycloheximide reduced the extent of DNA fragmentation and injury in thapsigargin‐treated cells. Dantrolene, an inhibitor of calcium release from intracellular stores partially abolished the effect of thapsigargin, suggesting that the initial Ca2+ rise may be the signalling event in this apoptotic cell death pathway. We propose that thapsigargin‐induced cell death in cultured neuronal cells maybe a useful system to study the molecular and genetic events involved in apoptosis.
cDNA sequence analysis of a novel neurotoxin homolog from Taiwan banded krait
Authors: Chang Long‐Sen , Lin Jordge 
Published: July 2007

AbstractThe cDNA encoding a novel protein was constructed from the cellular RNA isolated from the venom glands of Bungarus multicinctus (Taiwan banded krait) by reverse transcription‐polymerase chain reaction. The deduced amino acid sequence of this novel protein contains 68 amino acid residues with 10 cysteine residues. Comparative sequence analyses show that it is structurally related to α‐bungarotoxin and κ‐bungarotoxins from Bungarus multicinctus venom. Eight out of the ten cysteine residues in this protein are located at the homologous positions as those in the neurotoxins. However, instead of the fifth disulfide linkage appearing in loop II of α‐bungarotoxin and κ‐bungarotoxins, the other two cysteine residues in this novel toxin are situated at the N‐terminal region. Phylogenetic analyses suggest that it probably represents a small evolutionary divergence between the long and short neurotoxins.
Fucoidan inhibits leukocyte recruitment in a model peritonial inflammation in rat and blocks interaction of P‐selectin with its carbohydrate ligand
Authors: Preobrazhenskaya M. E. , Berman A. E. , Mikhailov V. I. , Ushakova N. A. , Mazurov A. V. , Semenov A. V. , Usov A. I. , Nifant'ev N. E. , Bovin N. V. 
Published: July 2007

AbstractNeutrophil recruitment into systemic inflammatory sites in vivo is thought to be initiated by selectin‐mediated endothelial adherence. The effect of fucoidan (natural sulfated polymer of L‐fucose) on the selectin dependent PMN migration into rat peritoneum following the induction of inflammation by peptone injection was studied. Peritonitis was characterized by an increase in the total cell number (from 45.3×106 to 91.6×106'rat), and by highly elevated PMN content (from 0.2% to 58%) in the rat peritoneal cavity 3 h after peptone injection. Intravenous administration of fucoidan was found to reduce, in a dose‐dependent manner, neutrophil migration into peritoneum. Fucoidan in a dose as low as 0.8 mg per rat caused 96.8% reduction of neutrophil extravasation. The inhibitory effect of fucoidan was also dependent on the time intervals between the peptone and fucoidan injections. The maximal inhibitory effect of fucoidan was observed within the first 15 rain after the induction of peritonitis and it was maintained at a level of 80% during 1.5 h. Administration of fucoidan 2.5 h after peptone injection had practically no effect on PMN extravasation. Since P‐selectin is known to play a key role at the earlier stages of PMN extravasation, it was suggested that the inhibitory effect of fucoidan was mostly due to its interaction with P‐selectin. The in vitro experiments demonstrated the high affinity of fucoidan for both isolated P‐selectin and P‐selectin in plasma membranes of activated platelets.
Evidence for the essential histidine residues in geranylgeranyl transferase type 1 from bovine testis
Authors: Kim Hyunkyung , Yoon Bo‐Young , Yang Chul‐Hak 
Published: July 2007

AbstractGeranylgeranyl transferase was purified 30,000‐fold by sequential use of 30‐50% ammonium sulfate fractionation, Q‐Sepharose anion exchange chromatography, Phenyl Superose hydrophobic interaction chromatography, Sephacryl S‐300 gel filtration chromatography, and peptide (YREKKFFCAIL) affinity chromatography. Geranylgeranyl transferase, when incubated with diethyl pyrocarbonate (DEPC), a histidine‐specific reagent, shows time‐dependent inactivation, and the activity is restored by the addition of neutral hydroxylamine. The inactivation follows pseudo‐first order kinetics with a second order rate constant of 0.319 M‐1min‐1. The overall results thus provide evidence that a histidine residue in the active site is involved in the catalytic mechaism of the geranylgeranyl transferase reaction.
Formation and characteristics of an unusual λ‐DNA species
Authors: Cao En‐hua , Sun Xue‐guang , Bai Chun‐li , Liu Ci‐quan , He Yu‐jian , Wang Xin‐wen , Fang Ye 
Published: July 2007

AbstractAn unusual DNA species, termed as DNA species A, has been isolated and purified from thermal‐denatured λ‐DNA Hind III by Sephadex G‐200 gel filtration. Our studies indicate that DNA species A is resistant to DNase I digestion and has a higher melting point. The new DNA species showed a lower absorbency at 260 nm, and a lower fluorescence quantum yield after interaction with ethidium bromide (EB) than native double‐stranded λ‐DNA. CD spectrum of DNA species A consists of a broad positive band centered at 245 nm and a weak negative band at 220 nm. transmission electron microscope (TEM) visualizations showed that their lengths of DNA species A fell mainly in three regions (300‐500 nm, 750‐1000 nm and 1500 nm) that corresponded to three fluorescence bands in the EB‐stained gels. Their apparent width and height were 65‐75 nm and 2.2 nm respectively as observed by images of atomic force microscope (AFM).
Thermal stabilization of carboxypeptidase a as a function of pH and ionic milieu
Authors: Li Xinhui , Solomon Beka 
Published: July 2007

AbstractIn this study we investigated the contribution of pH, phosphate anions and salt concentration to the catalytic and structural thermostability of the carboxypeptidase A (CPA). The concentration of 75‐100 mM phosphate as well as neutral pH values were found to be optimal for stabilizing CPA at high temperatures. Although moderate concentrations of sodium chloride had no effect on thermal stability, high concentrations of the salt destabilized the enzyme. The experimental results and theoretical analysis suggested that the main contribution to heat stabilization of CPA is related to intramolecular electrostatic interactions and Arginine and/or Lysine are the putative groups able to bind phosphate and stabilize the enzyme molecule against thermal denaturation.
Purification of recombinant human precursor acid α‐glucosidase
Authors: Van Hove Johan L. K. , Yang Helen W. , Oliver Letealia M. , Pennybacker Mark F. , Chen Yuan‐Tsong 
Published: July 2007

AbstractLarge quantities of recombinant acid α‐glucosidase are needed for in viva experimentation of enzyme replacement therapy in Pompe disease. We describe a new purification method for the purification of this recombinant enzyme from tissue culture medium consisting of concanavalin A affinity chromatography, hydrophobic interaction chromatography, affinity chromatography on Superdex, and anion exchange chromatography. The new method is amenable to scale up, and has increased speed, and improved reproducibility with similar high yield and purification efficiency when compared to previous methods.
Attenuation of renomedullary phospholipase C isozyme, PLC‐δ1, in spontaneously hypertensive rats
Authors: Lee Kweon‐Haeng , Cho Young‐Jin , Cha Seok Ho , Endou Hitoshi 
Published: July 2007

AbstractThe distributional patterns of PLC isozymes within the kidney were investigated using spontaneously hypertensive rats (SHRs) and normotensive Wistar‐Kyoto (WKY) rats at 4 and 12 weeks of age. PLC‐β1, PLC‐β3 and PLC‐δ1 quantified by Western blot analysis, were present in the highest concentrations in the inner medulla of rats at both 4 and 12 weeks of age. On the other hand, PLC‐β4, PLC‐γ1 and PLC‐γ2 were distributed almost equally among the regions for the rats of both ages. When compared with WKY rats at 12 weeks of age, the amounts of PLC‐β1, PLC‐β3, PLC‐γ1, PLC‐γ2, and PLC‐δ1 in the inner medulla of SHRs were significantly lower, and the amount of PLC‐δ1 in the inner stripe of the outer medulla was also significantly lower. Even at the prehypertensive stage at 4 weeks of age, the inner medullary concentration of PLC‐δ1 was significantly lower in SHRs than WKY rats. These results suggest that PLC‐δ1 would play an important role in the development of hypertension.
Sheep testicular and epididymal angiotensin converting enzyme: inhibitions by captopril, lisinopril and enalapril
Authors: Udupa E.G. Padmanabha , Rao N. Mallikarjuna 
Published: July 2007

AbstractInhibition of angiotensin converting enzyme(ACE) in presence of captopril(C), lisinopril(L) and enalapril(E) were investigated in testis and epididymis of sheep using Hip‐His‐Leu as substrate. Captopril, lisinopril and enalapril were competitive inhibitors of the enzyme from both tissues. Differences in the I50 and Ki values using these three inhibitors reflects the affinities of these inhibitors for the, ACE. In addition, the relative potencies of captopril, lisinopril and enalapril were different for testicular ACE(C > L > E) and epididymal ACE(L>C >E). This observation suggests differences between the active sites of the testicular and epididymal ACE which may reflect on their functions in vivo.
Vitamin D receptor in IMR‐90 human fibroblasts and antiproliferative effect of 1,25‐dihydroxyvitamin D3
Authors: Stio M. , Celli A. , Lunghi B. , Raugei G. , Modesti A. , Treves C. 
Published: July 2007

AbstractThis study examines the effect of 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3], serum or forskolin on the proliferation of IMR‐90 fetal lung fibroblasts and demonstrates, for the first time, the presence of 1,25(OH)2D3 receptor (VDR) in this cell line. In quiescent, subconfluent cultures neither the treatment with 100 nM 1,25(OH)2D3 nor that with 50 μM forskolin influenced proliferation, while a significant increase was observed after incubation of the cells with 10% fetal bovine serum. Either cell number, determined on growing IMR‐90 human fibroblasts after 48 or 72 h incubation with 100 nM 1,25(OH)2D3 or [3H]thymidine incorporation (24, 48 or 72 h incubation) significantly decreased, while protein content per cell increased. Northern blot analysis revealed the expression of the VDR gene, the VDR mRNA bands being prominent in 1,25(OH)2D3, serum or forskolin treated fibroblasts. VDR mRNA levels slightly decreased, when growing fibroblasts were exposed to 100 nM 1,25(OH)2D3 for 48 or 72 h.
Functional residues at the active site of bovine brain adenosine deaminase
Authors: Lupidi G. , Marmocchi F. , Venardi G. , Cristalli G. 
Published: July 2007

AbstractBrain adenosine deaminase was investigated in order to identify amino acid residues essential for its catalytic activity. The pH dependence of log Vmax shows that the enzyme activity depends on two ionizing groups with pK values of 5.4, that must be unprotonated, and 8.4, that must be protonated, for the catalysis. These same groups are observed in the Vmax/Km profiles. The plausible role of histidine residues at the active site of brain adenosine deaminase was proved by chemical modification with (DEP). The histidine specific reagent inactivated the enzyme following a pseudo first‐order kinetics with a second‐order rate constant of 8.9 10‐3 (±1.8 10‐3) M‐1 min‐1. The inhibition of the enzyme with PCMBS was studied monitoring the enzyme activity after incubation with the inhibitor. Brain adenosine deaminase exhibited a characteristic intrinsic tryptophan fluorescence with an emission peak centered at 335 nm. Stern‐Volmer quenching parameters in the presence of acrylamide and iodide indicated that tryptophan residues are buried in the native molecule. Tryptophan residues also showed a high heterogeneity that was increased after binding of ground‐ and transitionstate analogs to the enzyme.
Lectin activity in fruiting bodies of the edible mushroom Tricholoma mongolicum
Authors: Wang H. X. , Ng T. B. , Ooi V. E. C. 
Published: July 2007

AbstractThis study was undertaken to ascertain the existence and some of the characteristics of lectin in the fruiting bodies of the edible mushroom Tricholoma mongolicum. The fractionation procedure utilized entailed aqueous extraction, (NH4)2SO4 precipitation, dialysis, ion exchange chromatography on DEAE‐Sepharose and gel filtration on Sephadex G‐100. A similar procedure has been successfully employed for isolating lectins from cultured mycelia of the same species. It was found that the fruiting body lectin could not be purified with the same facility as the mycelial lectins. Although lectins from both fruiting bodies and cultured mycelia were adsorbed on DEAE‐Sepharose and possessed similar carbohydrate specificities, the fruiting body lectin was adsorbed on ConA‐Sepharose and hence probably glycoprotein in nature whereas the mycelial lectins are unglycosylated proteins.
Down‐regulation of protein kinase C‐α detected in human colorectal cancer
Authors: Suga Kenji , Sugimoto Isamu , Ito Hisao , Hashimoto Eikichi 
Published: July 2007

AbstractThe down‐regulation of protein kinase C (PKC) was examined by Western blot procedure on about 30 tissue samples derived from human colorectal cancer and the corresponding normal mucosa. PKC‐α down‐regulation was detected in 60% of the cancer tissues compared with the respective normal mucosa and was observed in a higher frequency with the tissues under more advanced cancer stages. However, the frequencies of the down‐regulation of PKC‐δ and PKC‐ζ were lower than that of PKC‐α. These results suggest that a decreased level of PKC‐α may affect the cell growth and tumor promotion in colorectal tissue.
Repeated mild heat shock delays ageing in cultured human skin fibroblasts
Authors: Rattan Suresh I. S. 
Published: July 2007

AbstractThe effects of repetitive mild heat shock (30 min, 41° C) on growth and various cellular and biochemical characteristics of human skin fibroblasts undergoing ageing in vitro were analysed. Human skin ceils not only tolerated more than 30 repeated heat shocks throughout their replicative lifespan, but also maintained several characteristics of young cells until late in life. Whereas the growth rates, population doubling rates, and cumulative population doubling levels achieved in vitro remained unaffected, age‐related changes in cellular morphology, cell size, cytoskeletal organisation, autofluorescence and neutral β‐galactosidase activity were significantly slowed down by repeated mild heat shock. These hormesis‐like effects of stress‐induced defence processes can be useful to elucidate the role of maintenance and repair mechanisms in ageing.
Erythrocyte antioxidant systems protect cultured endothelial cells against oxidant damage
Authors: Richards Ross S. , Roberts Timothy K. , Dunstan R. Hugh , McGregor Neil R. , Butt Henry L. 
Published: July 2007

AbstractA study was undertaken to assess the ability of the erythrocyte to protect other tissues against oxidative damage. Radiolabelled (51Cr) human umbilical vein endothelial cells (HUVEC) were incubated with erythrocytes and neutrophils activated with phorbol myristate acetate (PMA). Damage to the endothelial cells was indicated by release of radioactivity into the suspending medium. We found that the co‐incubation of HUVEC with an increasing range of erythrocyte concentrations resulted in a dose‐dependent reduction in the release of radioactivity. When the ability of superoxide to cross the erythrocyte membrane or the glutathione systems was inhibited, the extent of endothelial cell damage increased. Inhibition of the catalase system did not affect results. It was concluded that the erythrocytes afforded some protection against oxidative damage to the endothelial cells by taking up and deactivating the superoxide ions. This protection depends upon intact erythrocyte antioxidant systems. These data support the hypothesis that erythrocytes can provide antioxidant protection to other tissues in vivo.
Comparison of kinetic properties of amine oxidases from sainfoin and lentil and immunochemical characterization of copper/quinoprotein amine oxidases
Authors: Zajoncová Ludmila , Frébort Ivo , Luhová Lenka , Sebela Marek , Galuszka Petr , Pec Pavel 
Published: July 2007

AbstractKinetic properties of novel amine oxidase isolated from sainfoin (Onobrychis viciifolia) were compared to those of typical plant amine oxidase (EC 1.4.3.6) from lentil (Lens culinaris). The amine oxidase from sainfoin was active toward substrates, such as 1,5‐diaminopentane (cadaverine) with Km of 0.09 mM and 1,4‐diaminobutane (putrescine) with Km of 0.24 mM. The maximum rate of oxidation for cadaverine at saturating concentration was 2.7 fold higher than that of putrescine. The amine oxidase from lentil had the maximum rate for putrescine comparable to the rate of sainfoin amine oxidase with the same substrate. Both amine oxidases, like other plant Cu‐amine oxidases, were inhibited by substrate analogs (1,5‐diamino‐3‐pentanone, 1,4‐diamino‐2‐butanone and aminoguanidine), Cu2+ chelating agents (diethyltriamine, 1,10‐phenanthroline, 8‐hydroxyquinoline, 2,2′‐bipyridyl, imidazole, sodium cyanide and sodium azide), some alkaloids (L‐lobeline and cinchonine), some lathyrogens (β‐aminopropionitrile and aminoacetonitrile) and other inhibitors (benzamide oxime, acetone oxime, hydroxylamine and pargyline). Tested by Ouchterlony's double diffusion in agarose gel, polyclonal antibodies against the amine oxidase from sainfoin, pea and grass pea cross‐reacted with amine oxidases from several other Fabaceae and from barley (Hordeum vulgare) of Poaceae, while amine oxidase from the filamentous fungus Aspergillus niger did not cross‐react at all. However, using Western blotting after SDS‐PAGE with rabbit polyclonal antibodies against the amine oxidase from Aspergillus niger, some degree of similarity of plant amine oxidases from sainfoin, pea, field pea, grass pea, fenugreek, common melilot, white sweetclover and Vicia panonica with the A. niger amine oxidase was confirmed.