Da Silva, William

The formation of a mineral from a solution is under a number of different controlling factors (Crick 1986 Frausto da Silva Williams 1991). The simplest case we can consider is an equilibrium between a particular form of a mineral, say calcite, and the activities, not concentrations, of the ions, for example ... 

Fig. 2. The uptake of elements into a eukaryote cell, which is a large cell with numbers of compartments, evolving about 2 billion years ago. The functions of metal ions are extremely varied, controlled by gene expression of proteins, P, including pumps, and in part they control genetic expression by feedback to the gene. Some ions, especially Ca and Mn, are often exported or put into vesicles while Mg " " is also pumped out of cells in seawater. Details of the functions and activities of all the ions are given in Frausto da Silva Williams (1991).

Figure 3.118 Possible modes of cisplatin binding to DNA strands. (Reproduced from J.J.R. Frausto da Silva and R.J.P. Williams, The Biological Chemistry of the Elements, 1994, p. 539, by permission of Oxford University Press.)...

Trace metals can serve as essential nutrients and as toxic substances (Sunda et al, 1991 Frausto da Silva and Williams, 1991). For example, cobalt is a component of vitamin B-12. This vitamin is essential for nitrogen fixing algae. In contrast, copper is toxic to marine phytoplankton at free ion concentrations similar to those found in seawater (Sunda and... 

Fraiisto da Silva JJR, Williams RJP (1976) The Uptake of Elements by Biological Systems. 29 67-121... 

The work described in this article is presented in full in the text, Williams R.J.P. and Frausto da Silva, J.R.R., Bringing Chemistry to Life, Oxford University Press, Oxford, UK, 1999 All detailed references are to be found there. 

It is also clear that copper is of little significance in most of these organisms relative to its multitude of roles in multicellular eukaryotes, while in these eukaryotes the role of nickel and cobalt is further diminished. We may conjecture that biological systems did not use copper extensively before the advent of an oxidizing atmosphere based on dioxygen (Frausto da Silva and Williams, 1991). 

For a more detailed analysis of Co chemistry and B12 in particular, see Frausto da Silva and Williams (1991) and Lippard and Berg (1994), and for a recent review of Bi2-dependent enzymes, see Ludwig and Mathews (1997). 

Of the major solids formed from melts, many, but not all, at equilibrium, the overwhelming influence is of cooperative interaction between ionic units of similar shape and size as we see in crystals. Trace elements apart from forming isolated minerals are fractioned in bulk oxides, for example, in particular orders as the melt solidifies, and this reduces the relative availability of some elements such as Cr and Ni (see Williams, and Williams and Frausto da Silva (1999) in Further Reading). Again the interaction of selective molten minerals and water creates extremely reactive environments and such environments still exist, especially in the deep sea black smokers (hydrothermal vents), around which particular mixed minerals form, which could also have been involved in prebiotic chemistry and are still involved in the peculiarities of life in these smokers . In Figure 1.6 we summarise... 

Mason, B. and Moore, C.B. (1982). Principles of Geochemistry (4th ed.). Wiley, New York Press, F.S. and Siever, R. (1986). Earth (4th ed.). W.H. Freeman and Company, New York Stanley, S.M. (2002). Earth System History. W.H. Freeman and Company, New York Wayne, R.P. (2002). Chemistry of Atmospheres (3rd ed.). Oxford University Press, Oxford Williams, R. J.P. and Frausto da Silva, J.J.R. (1996). The Natural Selection of the Chemical Elements - The Environment and Life s Chemistry. Clarendon Press, Oxford... 

Wicken, J.S. (1987). Evolution, Thermodynamics and Information. Oxford University Press, New York Williams, RJ.P. and Frausto da Silva, J.J.R. (1996). The Natural Selection of the Chemical Elements - The Environment and Life s Chemistry. Clarendon Press, Oxford... 

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