Protein oxidation disease roles

Increased levels of ROS due to oxidative stress have been consistently found in cardiovascular diseases as atherosclerosis or hypertension [18]. There is certain evidence that the free radicals involved in Parkinson s disease are mainly due to the production of increased levels of free radicals during oxidative metabolism of dopamine [19]. Oxidative stress, manifested by protein oxidation and lipid peroxidation (LP), among other alterations, is a characteristic of Alzheimer s disease [20] and in the pathogenesis of diabetes related complications. Treatment with antioxidants seemed to be a promising therapeutic option for these diseases [21], The inflammatory nature of rheumatoid arthritis implies that a state of oxidative stress may also exist in this disease [22,23]. Also, free radicals have a certain role in Huntington s disease [24,25], age related degeneration [26], and some autoimmune disorders [27],... 

There is considerable debate concerning the role played by free radical reactions, protein oxidation, DNA damage and lipid peroxidation in human disease and toxicology. Radical species have indeed been implicated in many disease states (Table 2.1). The question as to whether free radicals are a major cause of tissue damage in human disease or an accompaniment to or a consequence of such injury is by no means clear in many instances. However, what is clear is that diseased or damaged tissues undergo radical reactions more readily than normal, which may exacerbate the primary lesion. 

Abstract Alzheimer s disease (AD) is the most common cause of dementia in the elderly and is characterized by senile plaques, neurofibrillary tangles, synapse loss, and progressive neuronal deficits. There is an abundance of evidence suggesting that oxidative stress is involved in the pathogenesis of Alzheimer s disease. Several investigations have revealed the presence of oxidation products of proteins, lipids, and DNA in postmortem tissue from AD patients, indices that are indicative of increased oxidative stress. In the present review we discuss the role of protein oxidation in the brain of subjects with AD and MCI. 

Fig 24.23. A model for the role of ROS and RNOS in neuronal degradation in Parkinson s disease. 1. Dopamine levels are reduced by monoamine oxidase, which generates H2O2. 2. Superoxide also can be produced by mitochondria, which SOD will convert to H2O2. Iron levels increase, which allows the Fenton reaction to proceed, generating hydroxyl radicals. 3. NO, produced by inducible nitric oxide synthase, reacts with superoxide to form RNOS. 4. The RNOS and hydroxyl radical lead to radical chain reactions that result in Upid peroxidation, protein oxidation, the formation of lipofuscin, and neuronal degeneration. The end result is a reduced production and release of dopamine, which leads to the clinical symptoms observed. 

While the fluid mosaic model of membrane stmcture has stood up well to detailed scrutiny, additional features of membrane structure and function are constantly emerging. Two structures of particular current interest, located in surface membranes, are tipid rafts and caveolae. The former are dynamic areas of the exo-plasmic leaflet of the lipid bilayer enriched in cholesterol and sphingolipids they are involved in signal transduction and possibly other processes. Caveolae may derive from lipid rafts. Many if not all of them contain the protein caveolin-1, which may be involved in their formation from rafts. Caveolae are observable by electron microscopy as flask-shaped indentations of the cell membrane. Proteins detected in caveolae include various components of the signal-transduction system (eg, the insutin receptor and some G proteins), the folate receptor, and endothetial nitric oxide synthase (eNOS). Caveolae and lipid rafts are active areas of research, and ideas concerning them and their possible roles in various diseases are rapidly evolving. 

The lack of zinc can also be a problem in biological systems and is responsible for disease states. For example, nitric oxide-dependent apoptosis can be induced in motor neurons by zinc-deficient SOD, and in some cases of amyotrophic lateral sclerosis, zinc-deficient SOD may participate in this type of oxidative mechanism involving nitric oxide.969 One form of hereditary human hair loss or alopecia was mapped to a specific gene and a mutation found in affected individuals. The gene encodes a single zinc finger transcription factor protein with restricted expression in the brain and skin.970 Zinc has been implicated in Alzheimer s via beta amyloid formation, and a role has been attributed for the cerebral zinc metabolism in the neuropathogenesis of Alzheimer s disease.971... 

The modification of amino acids in proteins and peptides by oxidative processes plays a major role in the development of disease and in aging (Halliwell and Gutteridge, 1989, 1990 Kim et al., 1985 Tabor and Richardson, 1987 Stadtman, 1992). Tissue damage through free radical oxidation is known to cause various cancers, neurological degenerative conditions, pulmonary problems, inflammation, cardiovascular disease, and a host of other problems. Oxidation of protein structures can alter activity, inhibit normal protein interactions, modify amino acid side chains, cleave peptide bonds, and even cause crosslinks to form between proteins. 

Polyphenol oxidase occurs within certain mammalian tissues as well as both lower (46,47) and higher (48-55) plants. In mammalian systems, the enzyme as tyrosinase (56) plays a significant role in melanin synthesis. The PPO complex of higher plants consists of a cresolase, a cate-cholase and a laccase. These copper metalloproteins catalyze the one and two electron oxidations of phenols to quinones at the expense of 02. Polyphenol oxidase also occurs in certain fungi where it is involved in the metabolism of certain tree-synthesized phenolic compounds that have been implicated in disease resistance, wound healing, and anti-nutrative modification of plant proteins to discourage herbivory (53,55). This protocol presents the Triton X-114-mediated solubilization of Vida faba chloroplast polyphenol oxidase as performed by Hutcheson and Buchanan (57). 

There is great interest in the mechanisms of cell death since better understanding might lead to therapy that slows the rate of aging and prevents or treats human disease. Two major processes of cell death have been described, apoptosis and neaosis other alternative pathways generally are variations of these (Formigli et al, 2000 Sperandio et al, 2000 Reed, 1999). Some of the intracellular events related to these types of death have been discovered (Reed, 2000). After exposure to noxious stimuli, the balance between antiapoptotic and proapoptotic influences can result in either survival or death. Many of these variable influences and the subsequent downstream concatenated events involve oxidation, which targets cellular components such as DNA, cellular proteins and membrane phospholipids. Our laboratory and others have studied the role of the redox-active cellular constituents nitric oxide ( NO) and membrane phospholipid... 

PolyADP-ribosylation has been reported to play a role in traumatic brain injury (TBI), excitotoxic, and oxidative injury. In the mitochondria after TBI, PARPs are activated and poIyADP-ribosylate multiple proteins involved in electron transfer. Since the ribosylation of these proteins shuts down electron transport, cells are sent into an apoptotic state. This gives insight into mitochondrial-based brain injuries and diseases. 

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