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排序方式: 共有144条查询结果,搜索用时 15 毫秒
1.
《Journal of molecular recognition : JMR》2017,30(3)
Pesticides are chemical substances that eliminate or control a variety of agricultural pests that damage crops and livestock. They not only affect the targeted pests but also affect the nontargeted systems, raising more concerns for their effect on both plant and animal systems. Cystatins (cysteine protease inhibitor) are ubiquitously present in all living cells and show a variety of important physiological functions. The present study shows the effect of different pesticides (pendimethalin, methoxyfenozide, and CuII hydroxide) on purified almond cystatin. Almond cystatin showed concentration‐dependent loss in papain inhibitory activity on interaction with the pesticides, showing maximum loss in the presence of Cu(II) hydroxide and minimum in the case of methoxyfenozide. Native polyacrylamide gel electrophoresis showed maximum degradation of purified cystatin in the presence of Cu(II) hydroxide with insignificant effect in the presence of methoxyfenozide. Structural alterations were significant in the case of Cu(II) hydroxide and less in the case of methoxyfenozide as revealed by UV and fluorescence spectral studies. Secondary structural alterations were further conformed by circular dichroism and Fourier transform infrared spectroscopy. The α‐helix content of almond cystatin decreases from 35.64% (native) to 34.83%, 30.79%, and 29.62% for methoxyfenozide‐, pendimethalin‐, and Cu(II) hydroxide–treated cystatin, respectively. A Fourier transform infrared study shows an amide I band shift for almond cystatin from 1649.15 ± 0.5 to 1646.48 ± 0.6, 1640.44 ± 0.6, and 1635.11 ± 0.3 cm−1 for methoxyfenozide, pendimethalin, and Cu(II) hydroxide, respectively. Values obtained for different thermodynamic parameters (ΔH 0, ΔG 0, N , and ΔS 0) by isothermal titration calorimetric experiments reveal maximum binding of almond cystatin with Cu(II) hydroxide followed by pendimethalin and little interaction with methoxyfenozide. 相似文献
2.
Metals such as Cu2+, Fe3+, and Zn2+ are major contributors to the biology of a brain in stages of health, aging, and disease because of their unique effects on both protein structures (misfolding) and oxidative stress. The relationship between metal ions and neurodegenerative diseases is very complicated. Our study highlights how metal ions influence amyloid formation at low pH and on preformed amyloid fibrils. By using thioflavin T assay, ANS fluorescence, Congo red assay, circular dichroism, and microscopy to elucidate the effects of Cu2+, Fe3+, and Zn2+ on goat brain cystatin (GBC) aggregation at low pH. Results showed that Cu2+ and Fe3+ inhibit fibril formation of GBC by promoting amorphous aggregates. However, Zn2+ exclusively promotes fibril formation at low pH, leading to the formation of more ordered aggregates. Furthermore, the combined results of these complementary methods also suggested that Cu2+ and Fe3+ destabilize the β-sheet secondary structure of preformed amyloid fibrils of GBC. 相似文献
3.
Daniel Keppler Patrice Waridel Magnus Abrahamson Daniel Bachmann José Berdoz Bernard Sordat 《生物化学与生物物理学报:疾病的分子基础》1994,1226(2):117-125
The lysosomal cystein proteinase cathepsin B is shown to be secreted by ten human colon carcinoma cell lines and to accumulate in culture media as a latent enzyme. The cell lines also secrete a physiological inhibitor of cathepsin B, cystatin C. A significant correlation was found between secretion of the latent enzyme and the inhibitor (r = 0.755, P < 0.01). The aim of the present study was to modulate the respective secretion of the two antagonists to test whether or not latency of cathepsin B was due to the concomitant secretion of the inhibitor. SW480 colon carcinoma cells were treated with the acidotropic agent ammonium chloride, phorbol 12-myristate 13-acetate, and the inflammatory cytokines TGF-β, TNF-α, and IL-1β. Ammonium chloride significantly increased latent cathepsin B levels without affecting the constitutive secretion of cystatin C. Phorbol 12-myristate 13-acetate induced a 4- to 5-fold increase in secreted latent cathepsin B, but did not alter significantly the accumulation of cystatin C in media. The cytokines, TGF-β, TNF-α, and IL-1β, had no major effect on the expression of these two antagonists. Latent cathepsin B released from human carcinoma cells could be efficiently activated by neutrophil elastate at neutral pH. It is concluded that latent cathepsin B is a true proenzyme rather than an enzyme-inhibitor comples. In addition, our data from neutrophil elastate activation experiments indicate that a proteolytic system for activation of the tumor cell-secreted latent enzyme may exist in vivo. 相似文献
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Cystatins are extensively studied cysteine protease inhibitors, found in wide range of organisms with highly conserved structural folds. S-type of cystatins is well known for their abundance in saliva, high selectivity and poorer activity towards host cysteine proteases in comparison to their immediate ancestor cystatin C. Despite more than 90% sequence similarity, the members of this group show highly dissimilar binding affinity towards papain. Cystatin M/E is a potent inhibitor of legumain and papain like cysteine proteases and recognized for its involvement in skin barrier formation and potential role as a tumor suppressor gene. However, the structures of these proteins and their complexes with papain or legumain are still unknown. In the present study, we have employed computational methods to get insight into the interactions between papain and cystatins. Three-dimensional structures of the cystatins are generated by homology modelling, refined with molecular dynamics simulation, validated through numerous web servers and finally complexed with papain using ZDOCK algorithm in Discovery Studio. A high degree of shape complementarity is observed within the complexes, stabilized by numerous hydrogen bonds (HB) and hydrophobic interactions. Using interaction energy, HB and solvent accessible surface area analyses, we have identified a series of key residues that may be involved in papain–cystatin interaction. Differential approaches of cystatins towards papain are also noticed which are possibly responsible for diverse inhibitory activity within the group. These findings will improve our understanding of fundamental inhibitory mechanisms of cystatin and provide clues for further research. 相似文献
7.
Marta Spodzieja Monika Rafalik Aneta Szymańska Aleksandra S. Kołodziejczyk Paulina Czaplewska 《Journal of molecular recognition : JMR》2013,26(9):415-425
Secondary amyloid A (AA) amyloidosis is an important complication of some chronic inflammatory diseases, primarily rheumatoid arthritis (RA). It is a serious, potentially life‐threatening disorder caused by the deposition of AA fibrils, which are derived from the circulatory, acute‐phase‐reactant, serum amyloid A protein (SAA). Recently, a specific interaction between SAA and the ubiquitous inhibitor of cysteine proteases—human cystatin C (hCC)—has been proved. Using a combination of selective proteolytic excision and high‐resolution mass spectrometry, the binding sites in the SAA and hCC sequences were assessed as SAA(86–104) and hCC(96–102), respectively. Here, we report further details concerning the hCC–SAA interaction. With the use of affinity tests and florescent ELISA‐like assays, the amino acid residues crucial for the protein interaction were determined. It was shown that all amino acid residues in the SAA sequence, essential for the formation of the protein complex, are basic ones, which suggests an electrostatic interaction character. The idea is corroborated by the fact that the most important residues in the hCC sequence are Ser‐98 and Tyr‐102; these residues are able to form hydrogen bonds via their hydroxyl groups. The molecular details of hCC–SAA complex formation might be helpful for the design of new compounds modulating the biological role of both proteins. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
Hitoshi Kusakabe Kenjiro Kodama Akira Kuninaka Hiroshi Yoshino Kenji Soda 《Bioscience, biotechnology, and biochemistry》2013,77(12):2531-2535
A mold strain Y244-2 capable of producing l-lysine α-oxidase, a new enzyme catalyzing the α-oxidative deamination of l-lysine, was identified as Trichoderma viride. Among strains belonging to the genus Trichoderma tested, only Trichoderma viride Y244-2 produced the enzyme in wheat bran culture. The maximum enzyme production by the mold grown on wheat bran was observed after 10 and 14 days incubation with and without NaN03, respectively. Addition of NaN03, NH4N03, adenine, purine nucleosides, l-histidine, glycine or l-glutamine to wheat bran stimulated the production of the enzyme. In the liquid culture, the enzyme was produced extracellulary under the aerobic conditions, although the production was much lower than that in the wheat bran culture. 相似文献
9.
Calero M Pawlik M Soto C Castaño EM Sigurdsson EM Kumar A Gallo G Frangione B Levy E 《Journal of neurochemistry》2001,77(2):628-637
Variant human cystatin C (L68Q) is an amyloidogenic protein. It deposits in the cerebral vasculature of Icelandic patients with cerebral amyloid angiopathy, leading to stroke. Wild-type and variant cystatin C are cysteine proteinase inhibitors which form concentration dependent inactive dimers; however, variant cystatin C dimerizes at lower concentrations and has an increased susceptibility to a serine protease. We studied the effect of the L68Q amino acid substitution on cystatin C properties, utilizing full length cystatin C purified in mild conditions from media of cells stably transfected with either the wild-type or variant cystatin C genes. The variant cystatin C forms fibrils in vitro detectable by electron microscopy in conditions in which the wild-type protein forms amorphous aggregates. We also show by circular dichroism, steady-state fluorescence and Fourier-transformed infrared spectroscopy that the amino acid substitution modifies cystatin C structure by destabilizing alpha-helical structures and exposing the tryptophan residue to a more polar environment, yielding a more unfolded molecule. These spectral changes demonstrate that variant cystatin C has a three-dimensional structure different from that of the wild-type protein. The structural differences between variant and wild-type cystatin C account for the susceptibility of the variant protein to unfolding, proteolysis and fibrillogenesis. 相似文献
10.
Dubin G Popowicz G Krajewski M Potempa J Dubin A Holak TA 《Journal of biomolecular NMR》2004,28(3):295-296
The increasing antibiotic resistance of an important human pathogen Staphylococcus aureus calls for the development of new therapeutic strategies. Staphylococcal cysteine proteases have been suggested as targets for such therapies. The recent discovery of staphostatins, specific protein inhibitors of these enzymes, gives prospects for the design and production of synthetic, low molecular weight analogs which might become drugs. We have decided to structurally characterize staphostatin A, a representative inhibitor of staphylococcal cysteine proteases, and to assess its binding mode to the target protease with the view of clarifying the specificity determinants. Here we report the (1)H, (15)N and (13)C NMR resonance assignments of staphostatin A. 相似文献