For present purposes, a protein-bound metal site consists of one or more metal ions and all protein side chain and exogenous bridging and terminal ligands that define the first coordination sphere of each metal ion. Such sites can be classified into five basic types with the indicated functions: (1) structural -- configuration (in part) of protein tertiary and/or quaternary structure; (2) storage -- uptake, binding, and release of metals in soluble form: (3) electron transfer -- uptake, release, and storage of electrons; (4) dioxygen binding -- metal-O{sub 2} coordination and decoordination; and (5) catalytic -- substrate binding, activation, and turnover. The authors present here a classification and structure/function analysis of native metal sites based on these functions, where 5 is an extensive class subdivided by the type of reaction catalyzed. Within this purview, coverage of the various site types is extensive, but not exhaustive. The purpose of this exposition is to present examples of all types of sites and to relate, insofar as is currently feasible, the structure and function of selected types. The authors largely confine their considerations to the sites themselves, with due recognition that these site features are coupled to protein structure at all levels. In themore » next section, the coordination chemistry of metalloprotein sites and the unique properties of a protein as a ligand are briefly summarized. Structure/function relationships are systematically explored and tabulations of structurally defined sites presented. Finally, future directions in bioinorganic research in the context of metal site chemistry are considered. 620 refs.« less

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Structural and Functional Aspects of Metal Sites in Biology

Zinc coordination, function, and structure of zinc enzymes and other proteins

The structural chemistry of metal thiolate complexes

Relatively little attention has been paid to metal ions with the nd[sup 10] and nd[sup 10](n+1)s[sup 2] (i.e., [open quotes]s[sup 2][close quotes]) configurations. In combination with various anionic and neutral ligands, these metal ions form a wide variety of cluster compounds, some of which have been known to be luminescent when irradiated with ultraviolet light. Prominent examples of this family are cuprous iodide clusters such as Cu[sub 4]I[sub 4]-(py)[sub 4] (1, py = pyridine), which shows [open quotes]luminescence thermochromism[close quotes]; that is, they display bright emissions with colors markedly dependent on the temperature. Here the authors present an overview of recent studies carried out both independently and jointly in the authors' laboratories focusing upon the remarkably rich, but relatively unexplored, photochemical and photophysical properties of various tetra-and hexanuclear d[sup 10] and s[sup 2] metal ion clusters in solution. 74 refs., 4 figs., 2 tabs.

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Photochemical and photophysical properties of tetranuclear and hexanuclear clusters of metals with d10 and s2 electronic configurations

Thiolato-complexes of the transition metals

The direct electrochemical synthesis and crystal structure of salts of [M4(SC6H5)10]2− anions (M = Zn, Cd)

Electrochemical preparation and structure of an unusual zinc(II) thiolato anionic cluster

The crystal structure of indium diiodide, indium(I) tetraiodoindate(III), In[InI4]

The direct electrochemical synthesis of adducts of bis(diphenylphosphino)methane(dppm) with copper(I) thiolates and the X-ray crystal structure of Cu4(μ-SC5H11)4(dppm)2

Masood A. Khan

Papers

The direct electrochemical synthesis and crystal structure of salts of [M4(SC6H5)10]2− anions (M = Zn, Cd)

Electrochemical preparation and structure of an unusual zinc(II) thiolato anionic cluster

The crystal structure of indium diiodide, indium(I) tetraiodoindate(III), In[InI4]

The direct electrochemical synthesis of adducts of bis(diphenylphosphino)methane(dppm) with copper(I) thiolates and the X-ray crystal structure of Cu4(μ-SC5H11)4(dppm)2

The direct electrochemical synthesis of zinc and cadmium catecholates and related compounds