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Alzheimer's disease - A groundbreaking approach


In clinical research the influence of certain metal cofactors (e.g, iron, copper, zinc, and manganese) on Alzheimer's disease and other protein-misfolding diseases (e.g., Amyotrophic Lateral Sclerosis or prion diseases) has been intensely discussed for a couple of years. These metal ions are usually bound to organic ligands in the cell, e.g., protein molecules that play an important role in different metal metabolisms. Metal chaperones (e.g., copper chaperone for superoxide dismutase) guide and protect metal ions (e.g., copper) to target molecules (e.g., superoxide dismutases) within the cell. The last-mentioned compounds are activated by copper ion transfer via specific protein-protein interactions and thus, may function as essential metalloenzymes. In these processes, the chaperones as well as the target proteins are present in their bioactive or native (3-D) conformation under regular physiological conditions.

Some extreme environments (e.g., pH, temperature, or salinity) may lead to toxic effects of certain metal ions (e.g., copper or zinc), followed by the formation of free radicals, protein-misfolding and aggregation of proteins (e.g., amyloids, A?A?). Furthermore, denatured (improperly folded) metallochaperones cannot accomplish their essential functions under non-denaturing conditions. As consequence, the homeostatic control of several metal ions is disturbed and the cells are subjected to oxidative stresses. In general, malfunctioning of metal cofactor metabolisms may have fatal influences on human and animal health (e.g., Alzheimer's, Huntington's, Parkinson's disease, BSE, Amyotrophic Lateral Sclerosis, cancers, Mucoviscidosis, Menkes and Wilson diseases, Creutzfeldt-Jakob disease).

For a deeper understanding of those protein-misfolding diseases, researchers must develop new biochemical approaches for separating globular and denatured metalloproteins in biological systems and determine their structure-function relationships in clinical samples of probands and patients. In this context, a combined procedure for isolating, identifying and quantifying biologically active metal cofactors (e.g., Zn, Cu, Ni, Pd, Co, Fe, Mn, Pt, Cd, Cr, and Mo) in biofluids (e.g., blood, cytosols, cerebrospinal fluid) was developed at Research Centre Juelich. The main components are NMR spectroscopy, ICP-MS and a standardized quantitative preparative native continuous polyacrylamide gel electrophoresis (QPNC-PAGE) method.

With the aid of these methods biochemists are enabled to obtain fundamental knowledge on different conformational states of known and unknown metalloproteins in living organisms and to introduce several metallochaperones as potential biomarkers in conformational diseases. The detailled knowledge about denatured and bioactive metallochaperones and other proteins or enzymes is a major prerequisite for an improved diagnosis and therapy of these degenerative diseases.

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Source: Forschungszentrum Jülich / Bernd Kastenholz, Institut Phytosphäre (ICG-3)

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