Globulins metal-binding

The nomenclature of the transferrins has developed along several different routes, as frequently is the case in protein and enzyme biochemistry. The transferrins from blood serum have been variously called the pi metal-binding globulin, siderophilin and transferrin. The one... 

These are metal-binding proteins. A P-globulin, termed transferrin is capable of combining witii iron, copper and zinc. This protein constitutes approximately 3% of tire total plasma protein. Another example is ceruloplasmin, which contains copper. 

This trace element is in combination with iron and selenium in the hydrogenase mentioned previously in the sections on iron and selenium, which is known to be active in oxidation-reduction reactions (giving or taking electrons), an important activity of a class of enzymes. Nickel also has a role in the regulation of hydrogenases. Nickel binds easily to amino acids and to proteins such as globulins (which can be turned into transporters of metals in the bloodstream). Nickel proteins may be used to stabilize certain molecules. 

Citrate buffer and saline (MCB) solutions were preelectrolyzed for 24 h at — 1100 mV versus SCE to remove metal ion impurities. Acetonitrile (MCB) was redistilled and stored over molecular sieves. DTPA (Aldrich), triethylamine (Aldrich), and isobutylchloroformate (Sigma) were of the highest available purity. HSA (essentially globulin free) and rabbit IgG specific for HSA (Sigma) were obtained in the lyophilized form. Indium was obtained as anhydrous, ultrapure InCls (Alfa Products). All solutions were prepared from distilled/deionized HgO of at least 10 ft resistivity. Protein A from Staphylococcus aureus (SPA, Enzyme Center) was employed as an immunoadsorbent. It was obtained as a 10% (w/v) suspension with a 1.47 mg/ml binding capacity for immune complexes. 2-mercaptoethanol, sodium dodecyl sulfate, and acrylamide reagents were all of electrophoretic grade (Bio-Rad). 

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