ovalbumin and Neurodegenerative-Diseases

The misfolding and aggregation of proteins is involved in some of the most prevalent neurodegenerative disorders. The importance of human serum albumin (HSA) stems from the fact that it is involved in bio-regulatory and transport phenomena. Here the effect of acetonitrile (ACN) on the conformational stability of HSA and by comparison, ovalbumin (OVA) has been evaluated in the presence and absence of NaCl. The results show the presence of significant amount of secondary structure in HSA at 70% ACN and in OVA at 50% ACN, as evident from far-UV Circular Dichroism (CD) and Attenuated Total Reflection Fourier transformed infra red spectroscopy (ATR-FTIR). Tryptophan and 8-Anilino-1-Naphthalene-Sulphonic acid (ANS) fluorescence indicate altered tryptophan environment and high ANS binding suggesting a compact "molten globule"-like conformation with enhanced exposure of hydrophobic surface area. However, in presence of NaCl no intermediate state was observed. Detection of aggregates in HSA and OVA was possible at 90% ACN. Aggregates possess extensive β-sheet structure as revealed by far-UV CD and ATR-FTIR. These aggregates exhibit increase Thioflavin T (Th T) fluorescence with a red shift of Congo red (CR) absorption spectrum. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis confirmed the presence of fibrillar aggregates. Single cell gel electrophoresis (SCGE) assay of these fibrillar aggregates showed the DNA damage resulting in cell necrosis confirming their genotoxic nature. Some proteins not related to any human disease form fibrils in vitro. In the present study ACN gives access to a model system to study the process of aggregation.

Topics: Acetonitriles; Albumins; Benzothiazoles; Circular Dichroism; Congo Red; Humans; Lymphocytes; Microscopy, Electron, Scanning; Neurodegenerative Diseases; Ovalbumin; Protein Structure, Secondary; Sodium Chloride; Spectroscopy, Fourier Transform Infrared; Thiazoles; X-Ray Diffraction

The etiology of neurodegenerative disorders is at present unknown. However, many of these disorders are associated with an increase in oxidative and inflammatory events. Although a small percentage of these disorders are familial cases linked to specific genetic defects, most are idiopathic. Thus, environmental factors are thought to play an important role in the onset and progression of such disorders. We have demonstrated that exposure (4 h, 5 days per week for 2 weeks) to concentrated airborne particulate matter increases inflammatory indices in brain of ovalbumin-sensitized BALB/c mice. Animals were divided into three exposure groups: filtered air (control), ultrafine particles, or fine and ultrafine particles. The levels of proinflammatory cytokines interleukin-1 alpha (IL-1alpha) and tumor necrosis factor alpha (TNF-alpha) were increased in brain tissue of mice exposed to particulate matter compared to that of control animals. Levels of the immune-related transcription factor NF-kappaB were also found to be substantially elevated in the brain of exposed groups compared with the control group. These data indicate that components of inhaled particulate matter may trigger a proinflammatory response in nervous tissue that could contribute to the pathophysiology of neurodegenerative diseases.

Topics: Air Pollutants; Animals; Antigens; Asthma; Biomarkers; Brain; Chemical Phenomena; Chemistry, Physical; Electrophoretic Mobility Shift Assay; Encephalitis; Enzyme-Linked Immunosorbent Assay; Interleukin-1; Lipopolysaccharides; Male; Mice; Mice, Inbred BALB C; Neurodegenerative Diseases; NF-kappa B; Ovalbumin; Particle Size; Tumor Necrosis Factor-alpha