Cobalt biochemistry

In its complex compounds, of which there are many thousands, Co almost invariably has a +3 oxidation number. Apparently, Co+s ion accompanied by six coordinating groups is particularly stable. Cobalt complexes are important in biochemistry. Some enzyme reactions go through a cobalt-complexing mechanism. Although only small traces are needed, cobalt is essential to the diet. 

Lin, Y. Nageswara Rao, B.D. Structural characterization of adenine nucleotides bound to Escherichia coli adenylate kinase. 2. P and C Relaxation measurements in the presence of cobalt(II) and manganese(ll). Biochemistry, 39, 3647-3655 (2000)... 

In contrast to iron and copper, which dominate the scene of transition metal biochemistry and are components of a variety of metalloproteins, cobalt occupies a relatively modest niche in biology. A biological function of cobalt can only be said to have been established at the molecular level in a few cases involving coninoid coenzymes (7). 

Most of the literature on cobalt(II) in biochemistry concerns its effects in various metal-activated enzyme systems (3). Many of the typical Mg2+-activated enzymes can work with Co2+, though usually at a low rate. In some other systems, where Mnz+ commonly is the best coenzyme, Co2+ gives high activities while other cations are less effective or inhibitory. A few enzymes, notably some metal-activated peptidases, are most efficient with Co2+, but other metal ions are also functional. It is not believed, however, that Co2+ is an important enzyme activator in vivo (4). 

Taylor, P. W., Feeney, J., and Burgen, A. S. V. Investigation of the mechanism of ligand binding with cobalt (II) human carbonic anhydrase by lH and 19F nuclear magnetic resonance spectroscopy. Biochemistry JO, 3866-3875 (1971). 

Mills S. A. Goto Y. SuQ. Plastino J. Klinman J. P. Mechanistic comparison of the cobalt-substituted and wild-type copper amine oxidase from Hansenula polymorpha. Biochemistry 2002, 41, 10577-10584. 

Sette, M., Paci, M., Desideri, A. and Rotillo, G. (1992) Formate as an NMR probe of anion binding to copper-zinc and copper-cobalt bovine erythrocyte superoxide dismutase. Biochemistry, 31, 2410-2415. 

Gessner RV, Quigley GJ, Wang AH-J, van der Marel GA, van Boom JH, Rich A (1985) Structural basis for stabilization of Z-DNA by cobalt hexaammine and magnesium cations. Biochemistry 24 237 - 240... 

Kobayashi, M. and Shimitzu, S. 1999. Cobalt proteins. European Journal of Biochemistry, 261 1-9. 

Kaliman, P.A. Nikitchenko I.V. Sokol, O.A. et al. Regulation of Heme Oxygenase Aetivity in Rat Liver during Oxidative Stress Induced by Cobalt Chloride and Mercury Chloride. Biochemistry (Moscow), No. 1 77-82 2001. 

Licht, S. S., Booker, S., and Stubbe, J., 1999a, Studies on the catalysis of carbon-cobalt bond homolysis by ribonucleoside triphosphate reductase evidence for concerted carbon-cobalt bond homolysis and thiyl radical formation. Biochemistry 38 12219 1233. 

Marsh, E. N. G., and Ballou, D. P., 1998, Coupling of cobalt-carbon bond homolysis and hydrogen atom abstraction in adenosylcobalamin-dependent glutamate mutase. Biochemistry 37 11864nll872. 

Padmakumar, R., and Banerjee, R., 1997, Evidence that cobalt-carbon bond homolysis is coupled to hydrogen atom abstraction from substrate in methylmalonyl-CoA mutase. Biochemistry 36 3713iB718. 

Yamanishi, M., Yamada, S., Mugumma, H., Murakami, Y., Tobimatsu, T., and Toraya, T., 1998b, Evidence for axial coordination of 5,6-dimethylbenzimidazole to the cobalt atom of adenosylcobalamin bound to diol dehydratase. Biochemistry 37 479994803. 

Fig. 2.20 Formal fitness landscape of various biocatalytic and inactive (i.e., the latter being located outside the window of essentiality ) metal ions for the carboxypeptidase A (Vallee and Williams 1968). The enzyme reconstituted by cobalt (treatment with EDTA, then addition of Co +) is considerably more active than the native Zn version , while Cd (and other ions) afford poorly to non-active metalloproteins in this case. (Relative) catalytic turnover rates are from Vallee and Williams 1968, x and c values this work and previous publications by this author. Here, sufficient abundance of the corresponding ions is taken for granted owing to in-vitro addition to apoprotein, so c k is not hmited by c, but merely represents the catalytic features pertinent to k, obtained from either biochemistry (several metal ions being present, e.g. in phosphatases) or experiments with reconstituted apoproteins...

Perhaps the most important area of biochemistry in which ESR is used is the study of metalloproteins. Transition metals in certain oxidation and spin states have unpaired electrons, are paramagnetic, and in many cases are amenable to ESR spectroscopy. The most commonly found transition metals in biological systems are iron, copper, molybdenum, cobalt, and manganese. The remainder, including metals such as vanadium and... 

Coordination complexes, particularly chelates, play fundamental roles in the biochemistry of both plants and animals. Trace amounts of at least nine transition elements are essential to life—vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, and molybdenum. 

Cobalt (Co) is essential for humans only as an integral part of vitamin (cobalamin). No other function for cobalt in the human body is loiown. Details of vitamin biochemistry and function are discussed above. Microflora of the human intestine cannot use cobalt to synthesize physiologically active cobalamin. The human vitamin B12 requirement must be supplied by the diet. Free (nonvitamin B12) cobalt does not interact with the body vitamin B12 pool. 

Hegg, E. L. (2004). Unravelling the structure and mechanism of acetyl-coenzyme A synthase. Accounts of Chemical Research, 37, 775—783. Kobayashi, M., Shimizu. (1999). Cobalt proteins. European Journal of Biochemistry, 261, 1—9. 

Volumes have been published about the biochemistry and pharmacology of elements such as iron, cobalt, zinc, etc. (see, for example, the articles by P.M. May and D.R. Williams in Iron Metabolism edited by... 

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