Metalloprotein metal coordination site

Table I. Selected Metalloprotein Metal Coordination Site Structure Based on X-Ray Crystallography...

The goal of many biomolecular NMR studies is characterization of global molecular structure. In metallo-biomolecules, and in particular, for paramagnetic species, it is sometimes preferable to use NMR to perform a more focused study of the metal ion coordination enviroiunent and the metal electronic structure. Metal sites show great variation in the effects on chemical shifts and line widths and thus often call for tailored approaches. In this section, characteristics of some of the metalloproteins metal sites most frequently studied by NMR are summarized. Examples have been selected to illustrate approaches described in this chapter such as metal substitution, use of pseudocontact shifts, RDCs, relaxation enhancement, and detection of nuclei other than H. 

Metal ions in metalloproteins tend to be rather feebly bound (Williams 1986), except for Cu(II) and few others, using just two to three coordination sites which link them to amino acid side chains of the protein. This fact has various ramifications for conditions of essentiality in a reproducing system. Figures 3.1 and 3.2 show some correlation between certain values of c and x (which are coupled to each other as long as the oxidation state is kept constant)... 

The biological catalytic activity of metalloproteins for redox reactions is usually associated with a particular coordination environment of the metal active site [160, 161], In particular, there has been considerable interest in 02-binding and -activation by non-heme metalloenzymes [162-167). A redox-active metal center is often associated with another metal center which can accelerate the redox process of O2... 

KH Chung, E Hong, Y Do, C-H Moon. Unusual six- and eight-coordinated cadmium(II) malonate complex relevance to 113Cd NMR probe of metal binding sites on metalloproteins. J Chem Soc Chem Commun 2333—2334, 1995. 

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