Metal chelate affinity chromatography is a pseudoaffinity protein purification technique first developed in the 1970s. The mode of adsorption relies upon the formation of weak coordinate bonds between basic groups on a protein surface with metal ions immobilized on chromatographic beads (Figure 6.17). The affinity medium is synthesized by covalent attachment of a metal chelator to the chromatographic bead via a spacer arm. Chelating agents, such as iminodiacetate, are capable of binding a number of metal ions (e.g. Fe, Co, Ni, Cu, Zn, Al), and binding effectively immobilizes the ion on the bead. The affinity gel is normally supplied without bound metal, so the gel can be 'charged' with the metal of choice (by flushing the column with a solution containing a salt of that metal, e.g. CuSO4 in the case of copper). The metal ions most commonly used are Zn2+, Ni2+ and Cu2+. Basic groups on protein surfaces, most notably the side chain of histidine residues,
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Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...