Metalloproteomics in the molecular study of cell physiology and disease.

Physical and chemical stresses as well as metal-related diseases can disrupt the normal trafficking of metal ions. Moreover, homeostatic imbalance of such metal ions may modulate essential cellular functions (including signal transduction pathways), may catalyze oxidative damage, and may affect the folding of nascent proteins. Here we describe a new qualitative subproteomic method for the detection, isolation, and identification of metal-interacting proteins. Combining both classical immobilized metal ion affinity chromatography (IMAC) and modern proteomic techniques (e.g., two dimensional gel electrophoresis [2-DE]), metal-specific proteins have been successfully isolated and identified to define a metalloproteome. These metal-specific proteomes may give new insights into metal-related pathophysiological processes, such as the allergic reaction to nickel, which represents the most common form of human contact hypersensitivity.

Novel fluorescence assay for tracking molecular and cellular allergen-protein interactions.

T cells recognizing nickel (Ni) are key mediators in human Ni allergy, which represents the most common form of human contact hypersensitivity. In contrast to well-characterized Ni-specific human T cell clones, molecular knowledge about the extra- and intracellular route(s) of antigen/allergen presentation and processing of Ni-specific epitopes is still fragmentary. Here, we demonstrate a new metal-specific fluorescent technique to detect and quantify metal ions, like Ni(2+), while they are associated with isolated metalloproteins. Moreover, utilizing the fluorescent metal sensor molecule Newport Green (NPG) a novel method has been developed, which permits the metal-specific detection of Ni(2+) binding to surface or intracellular structures of individual human antigen presenting cells by flow cytometry. We expect such metal-specific fluorescent analyses to contribute to a better basic understanding of molecular and cellular immune processes involved in Ni-specific T cell epitope generation and the pathogenesis of human nickel allergy.