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51.
Kim SY Marekov L Bubber P Browne SE Stavrovskaya I Lee J Steinert PM Blass JP Beal MF Gibson GE Cooper AJ 《Neurochemical research》2005,30(10):1245-1255
Transglutaminase activity was found to be present in highly purified non-synaptosomal rat brain mitochondria. A 78-kDa protein
in these organelles was shown to be a transglutaminase 2 substrate, and incubation of a non-synaptosomal mitochondrial lysate
with transglutaminase 2 yielded high-Mr proteins. The 78-kDa protein was identified as mitochondrial aconitase by MALDI-TOF analysis. Aconitase activity was decreased
in a dose-dependent manner when non-synaptosomal rat brain mitochondria were incubated with transglutaminase 2. Transglutaminase
activity is increased about 2-fold in the mitochondrial fraction of HD caudate. Moreover, Western blotting of the mitochondrial
fraction revealed that most of the mitochondrial aconitase in HD caudate is present as high-Mr aggregates. Aconitase activity was previously shown to be decreased in Huntington disease (HD) caudate (a region severely
damaged by the disease). The present findings suggest that an increase of transglutaminase activity in HD caudate may contribute
to mitochondrial dysfunction by incorporating aconitase into inactive polymers. 相似文献
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Klivenyi P Starkov AA Calingasan NY Gardian G Browne SE Yang L Bubber P Gibson GE Patel MS Beal MF 《Journal of neurochemistry》2004,88(6):1352-1360
Altered energy metabolism, including reductions in activities of the key mitochondrial enzymes alpha-ketoglutarate dehydrogenase complex (KGDHC) and pyruvate dehydrogenase complex (PDHC), are characteristic of many neurodegenerative disorders including Alzheimer's Disease (AD), Parkinson's disease (PD) and Huntington's disease (HD). Dihydrolipoamide dehydrogenase is a critical subunit of KGDHC and PDHC. We tested whether mice that are deficient in dihydrolipoamide dehydrogenase (Dld+/-) show increased vulnerability to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), malonate and 3-nitropropionic acid (3-NP), which have been proposed for use in models of PD and HD. Administration of MPTP resulted in significantly greater depletion of tyrosine hydroxylase-positive neurons in the substantia nigra of Dld+/- mice than that seen in wild-type littermate controls. Striatal lesion volumes produced by malonate and 3-NP were significantly increased in Dld+/- mice. Studies of isolated brain mitochondria treated with 3-NP showed that both succinate-supported respiration and membrane potential were suppressed to a greater extent in Dld+/- mice. KGDHC activity was also found to be reduced in putamen from patients with HD. These findings provide further evidence that mitochondrial defects may contribute to the pathogenesis of neurodegenerative diseases. 相似文献
53.
Strandberg E Tiltak D Ehni S Wadhwani P Ulrich AS 《Biochimica et biophysica acta》2012,1818(7):1764-1776
The membrane alignment of the amphiphilic α-helical model peptide MSI-103 (sequence [KIAGKIA](3)-NH(2)) was examined by solid state (2)H-NMR in different lipid systems by systematically varying the acyl chain length and degree of saturation, the lipid head group type, and the peptide-to-lipid molar ratio. In liquid crystalline phosphatidylcholine (PC) lipids with saturated chains, the amphiphilic helix changes its orientation from a surface-bound "S-state" to a tilted "T-state" with increasing peptide concentration. In PC lipids with unsaturated chains, on the other hand, the S-state is found throughout all concentrations. Using phosphatidylethanolamine lipids with a small head group or by addition of lyso-lipids with only one acyl chain, the spontaneous curvature of the bilayer was purposefully changed. In the first case with a negative curvature only the S-state was found, whereas in systems with a positive curvature the peptide preferred the obliquely immersed T-state at high concentration. The orientation of MSI-103 thus correlates very well with the shape of the lipid molecules constituting the membrane. Lipid charge, on the other hand, was found to affect only the initial electrostatic attraction to the membrane surface but not the alignment preferences. In bilayers that are "sealed" with 20% cholesterol, MSI-103 cannot bind in a well-oriented manner and forms immobilized aggregates instead. We conclude that the curvature properties of a membrane are a key factor in the interactions of amphiphilic helical peptides in general, whose re-alignment and immersion preferences may thus be inferred in a straightforward manner from the lipid-shape concept. 相似文献
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According to their distinct biological functions, membrane-active peptides are generally classified as antimicrobial (AMP),
cell-penetrating (CPP), or fusion peptides (FP). The former two classes are known to have some structural and physicochemical
similarities, but fusogenic peptides tend to have rather different features and sequences. Nevertheless, we found that many
CPPs and some AMPs exhibit a pronounced fusogenic activity, as measured by a lipid mixing assay with vesicles composed of
typical eukaryotic lipids. Compared to the HIV fusion peptide (FP23) as a representative standard, all designer-made peptides
showed much higher lipid-mixing activities (MSI-103, MAP, transportan, penetratin, Pep1). Native sequences, on the other hand,
were less fusogenic (magainin 2, PGLa, gramicidin S), and pre-aggregated ones were inactive (alamethicin, SAP). The peptide
structures were characterized by circular dichroism before and after interacting with the lipid vesicles. A striking correlation
between the extent of conformational change and the respective fusion activities was found for the series of peptides investigated
here. At the same time, the CD data show that lipid mixing can be triggered by any type of conformation acquired upon binding,
whether α-helical, β-stranded, or other. These observations suggest that lipid vesicle fusion can simply be driven by the
energy released upon membrane binding, peptide folding, and possibly further aggregation. This comparative study of AMPs,
CPPs, and FPs emphasizes the multifunctional aspects of membrane-active peptides, and it suggests that the origin of a peptide
(native sequence or designer-made) may be more relevant to define its functional range than any given name. 相似文献
56.
Sweety A. Wadhwani Utkarsha U. Shedbalkar Richa Singh Meena S. Karve Balu A. Chopade 《World journal of microbiology & biotechnology》2014,30(10):2723-2731
Gold nanoparticles have enormous applications in cancer treatment, drug delivery and nanobiosensor due to their biocompatibility. Biological route of synthesis of metal nanoparticles are cost effective and eco-friendly. Acinetobacter sp. SW 30 isolated from activated sewage sludge produced cell bound as well as intracellular gold nanoparticles when challenged with HAuCl4 salt solution. We first time report the optimization of various physiological parameters such as age of culture, cell density and physicochemical parameters viz HAuCl4 concentration, temperature and pH which influence the synthesis of gold nanoparticles. Gold nanoparticles thus produced were characterized by various analytical techniques viz. UV–Visible spectroscopy, X-ray diffraction, cyclic voltammetry, transmission electron microscopy, selected area electron diffraction, high resolution transmission electron microscopy, environmental scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and dynamic light scattering. Polyhedral gold nanoparticles of size 20 ± 10 nm were synthesized by 24 h grown culture of cell density 2.4 × 109 cfu/ml at 50 °C and pH 9 in 0.5 mM HAuCl4. It was found that most of the gold nanoparticles were released into solution from bacterial cell surface of Acinetobacter sp. at pH 9 and 50 °C. 相似文献
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Twenty four fungi were isolated from ear wax or otitis media of agricultural field workers, of which 18 are being reported for the first time from India. Direct observation, revealed the presence of hyphal fragments, spores of Alternaria, Bipolaris, conidial head of Aspergillus, smut teliospores and pollen. Spores of only four fungi, Alternaria humicola, Aspergillus niveus, Bipolaris spicifera and Fusarium moniliforme germinated in otitis media at 37 ° C, and their germination was affected by relative humidity. Alternaria humicola and Aspergillus niveus appeared to be the causative agents of otomycosis, and otitis media is fungistatic in nature. 相似文献
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A new species ofPenicillium belonging to theP.funiculosum series of the Biverticillata — Symmetrica section is described from the rhizosphere ofBrassica campestris var.toria. The species is characterized by the presence of penicilli with 8–12 metulae on malt-extract agar and a very limited sporulation on Czapek-Dox agar. The species is namedPenicillium korosum on account of its broom-like penicilli.The authors are grateful to Prof. Kenneth B. Raper, Dr. Amelia Stolk and Dr. D. B. Prest for valuable comments, to Rev. Fr. Prof. Dr. Santapau and Fr. Ignatius Menezes for latinizing the specific diagnosis and to the Council of Scientific and Industrial Research, India, for financial assistance. 相似文献