Enzymes metal chelates

Elution of the bound antibody-enzyme conjugate occurs by only a slight shift in pH to acidic conditions or through the inclusion of a metal-chelating agent like EDTA or imidazole in the binding buffer. Either method of elution is mild compared to most immunoaffinity separation techniques (discussed in the previous section). Thus, purification of the antibody-enzyme complex can be done without damage to the activity of either component. 

Li, M., and Meares, C.F. (1993) Synthesis, metal chelate stability studies, and enzyme digestion of a peptide-liked DOTA derivatives and its corresponding radiolabeled immunoconjugates. Bioconjugate Chem. 4, 275-283. 

This enzyme [EC 3.4.13.3] (also referred to as Xaa-His dipeptidase, X-His dipeptidase, aminoacylhistidine dipeptidase, and homocarnosinase), is a zinc-dependent dipeptidase that catalyzes the hydrolysis of Xaa-His dipeptides. Carnosine, homocarnosine, and anserine are preferred substrates for this mammalian cytosolic enzyme. Other aminoacylhistidine dipeptides are weaker substrates (including homoanserine). The enzyme is activated by thiols and inhibited by metal-chelating agents. O. W. Griffith (1986) Ann. Rev. Biochem. 55, 855. 

Mammalian Cell Protease Inhibitor CocktaiL These should contain AEBSF, pepstatin A, E-64, bestatin, leupeptin, and aprotinin. (Metal chelators can be added to suppress the activity of calcium ion-dependent proteases such as calpain. Again, one must determine whether the protein or enzyme being purified does not require a divalent metal cofactor for stabihty or activity.)... 

Chelating agents are widely used as specific antidotes for heavy metals. They form stable, soluble, nontoxic complexes and in easily excreted form. They promote dissociation of bound metal from tissue enzymes and other functional macromolecules. These metal chelates are water soluble, e.g. EDTA, BAL, desferrioxamine etc. 

Several tetrahedral cuprous phenanthroline complexes, known inhibitors of transcription, were tested against integrase and shown to be reasonably effective inhibitors [56] IC50 values in the range of 1-10 jiMwere determined (for example, the neocuproine-Cu+ complex, XII). Analyses of the mode of inhibition demonstrated that these compounds act noncompetitively, and that inhibition does not correlate with inhibition of DNA binding. Thus, it has been proposed that these metal chelates may act at a site distant from the active site, or perhaps in the context of an enzyme-DNA complex. 

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