Rifampicin inhibits alpha-synuclein fibrillation and disaggregates fibrils

The aggregation of alpha-synuclein in dopaminergic neurons of the substantia nigra is a critical step in the pathogenesis of Parkinson's disease. We show that the antibiotic rifampicin inhibited alpha-synuclein fibrillation and disaggregated existing fibrils in a concentration-dependent manner. Size-exclusion chromatography data indicated that rifampicin stabilized alpha-synuclein as both a monomer and soluble oligomers comprised of partially folded alpha-synuclein. Experiments using aged samples of rifampicin indicated that the most active species in inhibiting fibrillation and disaggregating fibrils is an oxidation product of rifampicin, which was confirmed in experiments under anaerobic conditions. These results indicate that rifampicin-mediated inhibition of alpha-synuclein fibrillation and disaggregation of fibrils involves preferential stabilization of monomeric and soluble oligomeric forms, and that rifampicin potentially may have therapeutic application for Parkinson's disease.     

Multitude of binding modes attainable by intrinsically disordered proteins: a portrait gallery of disorder-based complexes

Proteins are constantly involved in the multitude of various interactions creating sophisticated networks which define and control all (or almost all) the biological processes taking place in any living organism. Intrinsically disordered proteins or regions play a number of crucial roles in mediating protein interactions. The lack of fixed structure protruding to the high level of intrinsic dynamics and almost unrestricted flexibility at various structure levels, being the major characteristics of intrinsically disordered proteins, provides them with unprecedented advantages over the ordered proteins. The binding modes attainable by disordered proteins are highly diverse, creating a multitude of unusual complexes. Although the majority of studied to date intrinsic disorder-based complexes are ordered or static entities originating due to the global or local disorder-to-order transitions, a new development is the discovery of dynamic complexes in which intrinsically disordered proteins continue to sample an ensemble of rapidly interconverting conformations mostly devoid of structure even in their bound state. The goal of this critical review is to illustrate binding plasticity of intrinsically disordered proteins by representing a portrait gallery of the disorder-based complexes (119 references).     

Comparative Analysis of the Antiviral Activity of Camel,Bovine, and Human Lactoperoxidases Against Herpes Simplex Virus Type 1

Lactoperoxidase is a milk hemoprotein that acts as a non-immunoglobulin protective protein and shows strong antimicrobial activity. Bovine milk contains about 15 and 7 times higher levels of lactoperoxidase than human colustrum and camel milk, respectively. Human, bovine, and camel lactoperoxidases (hLPO, bLPO, and cLPO, respectively) were purified as homogeneous samples with specific activities of 4.2, 61.3, and 8.7 u/mg, respectively. The optimal working pH was 7.5 (hLPO and bLPO) and 6.5 (cLPO), whereas the optimal working temperature for these proteins was 40 °C. The K _m of hLPO, cLPO, and bLPO were 17, 16, and 19 mM, and their corresponding V _max values were 2, 1.7, and 2.7 μmol/min ml. However, in the presence of H₂O₂, the K _m values were 11 mM for hLPO and cLPO and 20 mM for bLPO, while the corresponding V _max values were 1.17 for hLPO and 1.4 μmol/min ml for cLPO and bLPO. All three proteins were able to inhibit the herpes simplex virus type 1 (HSV-1) in Vero cell line model. The relative antiviral activities were proportional to the protein concentrations. The highest anti-HSV-1 activity was exhibited by bLPO that inhibited the HSV particles at a concentration of 0.5 mg/ml with the relative activity of 100%.

     

Alpha-synuclein misfolding and neurodegenerative diseases

Alpha-synuclein is an abundant presynaptic brain protein, misfolding, aggregation and fibrillation of which are implicated as critical factors in several neurodegenerative diseases. The list of the well-known synucleinopathies includes such devastating disorders as Parkinson's disease, Lewy body variant of Alzheimer's disease, diffuse Lewy body disease, dementia with Lewy bodies, multiple system atrophy, and neurodegeneration with brain iron accumulation type I. The precise functions of alpha-synuclein remain elusive, but there are evidence indicating its involvement in regulation vesicular release and/or turnover and synaptic function in the central nervous system. It might play a role in neuronal plasticity responses, bind fatty acids, regulate certain enzymes, transporters, and neurotransmitter vesicles, be involved in neuronal survival and even can act as a molecular chaperone. Structurally, alpha-synuclein is an illustrative member of the rapidly growing family of natively unfolded (or intrinsically disordered) proteins and considerable knowledge has been accumulated about its structural properties and conformational behavior. The molecular mechanisms underlying misfolding, aggregation and fibrillation of alpha-synuclein and the role of various environmental and genetic factors in stimulation and inhibition of these processes are relatively well understood. Here, the main structural features of alpha-synuclein, its functions, and involvement in various human diseases are summarized providing a foundation for better understanding of the biochemistry, biophysics and neuropathology of alpha-synuclein aggregation.     

Quantifying uncertainty in the measurement of arsenic in suspended particulate matter by Atomic Absorption Spectrometry with hydride generator

Arsenic is the toxic element, which creates several problems in human being specially when inhaled through air. So the accurate and precise measurement of arsenic in suspended particulate matter (SPM) is of prime importance as it gives information about the level of toxicity in the environment, and preventive measures could be taken in the effective areas. Quality assurance is equally important in the measurement of arsenic in SPM samples before making any decision. The quality and reliability of the data of such volatile elements depends upon the measurement of uncertainty of each step involved from sampling to analysis. The analytical results quantifying uncertainty gives a measure of the confidence level of the concerned laboratory. So the main objective of this study was to determine arsenic content in SPM samples with uncertainty budget and to find out various potential sources of uncertainty, which affects the results. Keeping these facts, we have selected seven diverse sites of Delhi (National Capital of India) for quantification of arsenic content in SPM samples with uncertainty budget following sampling by HVS to analysis by Atomic Absorption Spectrometer-Hydride Generator (AAS-HG). In the measurement of arsenic in SPM samples so many steps are involved from sampling to final result and we have considered various potential sources of uncertainties. The calculation of uncertainty is based on ISO/IEC17025: 2005 document and EURACHEM guideline. It has been found that the final results mostly depend on the uncertainty in measurement mainly due to repeatability, final volume prepared for analysis, weighing balance and sampling by HVS. After the analysis of data of seven diverse sites of Delhi, it has been concluded that during the period from 31^st Jan. 2008 to 7^th Feb. 2008 the arsenic concentration varies from 1.44 ± 0.25 to 5.58 ± 0.55 ng/m³ with 95% confidence level (k = 2).     

Fluorescent proteins as biomarkers and biosensors: throwing color lights on molecular and cellular processes

Green fluorescent protein (GFP) from jellyfish Aequorea victoria is the most extensively studied and widely used in cell biology protein. GFP-like proteins constitute a fast growing family as several naturally occurring GFP-like proteins have been discovered and enhanced mutants of Aequorea GFP have been created. These mutants differ from wild-type GFP by conformational stability, quantum yield, spectroscopic properties (positions of absorption and fluorescence spectra) and by photochemical properties. GFP-like proteins are very diverse, as they can be not only green, but also blue, orange-red, far-red, cyan, and yellow. They also can have dual-color fluorescence (e.g., green and red) or be non-fluorescent. Some of them possess kindling property, some are photoactivatable, and some are photoswitchable. This review is an attempt to characterize the main color groups of GFP-like proteins, describe their structure and mechanisms of chromophore formation, systemize data on their conformational stability and summarize the main trends of their utilization as markers and biosensors in cell and molecular biology.