Cobalt protein-functionalized

The ONIOM protein system contains the substrate, methylmalonyl-CoA, bound to the active site, the cofactor (AdoCbl) and all amino acids within a 15-A radius from the cobalt atom. The active-site selection contains a truncated AdoCbl and the imidazole ring of its lower ligand. The QM part was calculated using the BP86 functional [31, 72] because it gives better agreement with experimental Co—C bond energies [73, 74], This a different choice of functional compared to the other studies in the present review. 

A. J. Bearden, W. R. Durnham Iron Electronic Configurations in Proteins Studies by Moss-bauer Spectroscopy. - K Wiitkrich Structural Studies of Hemes and Hemoproteins by Nuclear Magnetic Resonance Spectroscopy. -H. A 0. Hill,A. Roder, R. J. P. Williams The Chemical Nature and Reactivity of Cytochrome P-450. - S. Lindskog Cobalt (II) in Metalloenzymes. A Reporter of Structure-Function Relations. 

Some elements are essential to the composition or function of the body. Since the body is mostly water, hydrogen and oxygen are obviously essential elements. Carbon (C) is a component of all life molecules, including proteins, lipids, and carbohydrates. Nitrogen (N) is in all proteins. The other essential nonmetals are phosphorus (P), sulfur (S), chlorine (Cl), selenium (Se), fluorine (F), and iodine (I). The latter two are among the essential trace elements that are required in only small quantities, particularly as constituents of enzymes or as cofactors (nonprotein species essential for enzyme function). The metals present in macro amounts in the body are sodium (Na), potassium (K), and calcium (Ca). Essential trace elements are chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), molybdenum (Mo), nickel (Ni), and perhaps more elements that have not yet been established as essential. 

In addition to proteins and calories, the patients with PEM must be replenished with respect to vitamins and micronutrients especially to enhance antioxidant status. Due to heavy vitamin A losses that occur during infections and PEM, vitamin A supplements are necessary to prevent blindness. Selenium, zinc, manganese, and cobalt are important micronutrients deficient in patients with PEM and therefore need to be replaced. These micronutrients play a vital role in the function of several enzymes (e.g., selenium in glutathione peroxidase). Iron must be excluded from the diet in the initial stage since early administration increases the risk of free-radical production and infection. 

Table 53 gives a list of a number of cobalt(III)-superoxo complexes which have been isolated as crystalline solids. There is a marked preponderance of complexes of the type [Co(SB)(B)(02)] (SB = SchifF base). The base adducts of simple Co11 porphyrins have low affinities for dioxygen at room temperature and consequently their 1 1 adducts with 02 are not isolable. In contrast, exposure of a solid sample of Collman s picket fence porphyrin system [Co(TpivPP)(iV-Meim)] to 1 atm of dioxygen for 24 h produces [Co(TpivPP)(A(-Meim)(02)] (200).654 The pivalamido pickets in this compound exercise control of solvation about the coordinated dioxygen moiety and the stability is comparable with that of CoMb02,655 where the globin protein environment performs the same function. 

Figure 1 An example of the way metallo-enzymes are under controlled formation through both controlled uptake (rejection) of a metal ion and controlled synthesis of all the proteins connected to its metabolism and functions. The example is that of iron. Iron is taken up via a molecular carrier by bacteria but by a carrier protein, transferrin, in higher organisms. Pumps transfer either free iron or transferrin into the cell where Fe + ions are reduced to Fe + ions. The Fe + ions form heme, aided by cobalamin (cobalt 2 controls) and a zinc enzyme for a-laevulinic acid (ALA) synthesis. Heme or free iron then goes into several metallo-enzymes. Free Fe + also forms a metallo-protein transcription factor, which sees to it that synthesis of all iron carriers, storage systems, metallo-proteins, and metallo-enzymes are in fixed amounts (homeostasis). There are also iron metallo-enzymes for protection including Fe SOD (superoxide dismutase). Adenosine triphosphate (ATP) and H+ gradients supply energy for all processes. See References 1 -3.

---