Main description:

Transition metal ions in biological systems are of interest in biology, biochemistry, chemistry, medicine, and physics. Scien tists with rather different viewpoints, employing many methods, have contributed to this area. A concise review of the current state of the field will, to some extent, reflect the special knowledge of the person writing it - in this case application of physical methods to the investigation of metal coordination. x ray diffraction is one of the most important of these methods, but a useful treatment of X-ray structure analysis would be com parable in size with and beyond the scope of the monograph. Many results of X-ray diffraction studies are, of course, presented. Electron paramagnetic resonance spectroscopy has played a major part in the rapid advance in knowledge of the electronic struc tures of transition metal ions in biological systems. More gener ally, measurements involving light, microwaves, and magnetic fields are capable of producing much new information, and the required instrumentation is available at most research institu tions. Therefore light absorption and paramagnetic resonance are treated in depth. The principles described in the latter discus sions are broadly applicable, for example to the promising tech niques of X-ray spectroscopy (utilizing synchrotron radiation) and lanthanide-perturbed, very high-resolution nuclear magnetic resonance spectroscopy.

Contents:

1 The Role of Transition Metal Ions in Biological Oxidation and Related Processes.- 1. Transition Metal Ions.- 2. Prosthetic Groups.- 3. Equilibrium Considerations in Reactions of Transition Metals.- a) Site Stability: Equivalent Ligands, Chelation, and Other Factors.- b) Electron Transfer and Redox Potentials.- 4. Molecular Functions of Proteins Containing Transition Metal Ion Prosthetic Groups.- a) Oxygen Carriage.- b) Oxygen Utilization.- c) Hydroperoxide Reactions.- d) Electron Transfer, Protein to Protein.- e) Hydrogen Atom Transfer from Substrate to Coenzyme or Substrate.- f) Nitrogen Utilization.- g) Hydrogen Utilization.- h) Hydrogen Peroxide Formation from Superoxide Radicals.- i) Methyl Transfer and Internal Hydrogen Transfer.- j) Utilization, Production, and Transfer of Ammonia.- k) Oxygen Evolution.- 5. The Role Which a Transition Metal Ion Plays in the Function of a Protein.- 6. Experimental Methods.- a) Isolation and Identification of Prosthetic (Nonprotein) Ligands.- b) X-ray Diffraction from Protein Single Crystals.- c) Electron Paramagnetic Resonance and Related Measurements.- d) Optical Measurements.- e) Measurements Utilizing Nuclei.- 7. Some Aspects of the Role of the Polypeptide in the Functioning of Proteins Containing Transition Metal Ions.- 2 Metal Coordination in Proteins.- 1. Ligands.- 2. The Established Coordination in Several Proteins.- a) Insulin.- b) Carboxypeptidase.- c) Myoglobin and Hemoglobin.- d) Myohemerythrin and Hemerythrin.- e) Cytochrome c.- f) Cytochrome b5.- g) Copper, Zinc Superoxide Dismutase.- h) Rubredoxin.- i) Ferredoxin and High Potential Iron-Sulfur Protein (HiPiP).- 3. Covalency.- 4. Some Aspects of Differences in Heme Binding.- 3 Copper.- 1. Cupric Peptides.- 2. EPR of Cupric Peptides and Related Complexes.- 3. The Blue Proteins.- 4. Magnetic and Optical Properties of Quantum Mechanical Models of the Cupric Ion.- 5. "Nonblue" Coordination in Copper Proteins.- 4 Heme Iron.- 1. Valence and Spin States of Iron.- 2. Magnetic Susceptibility.- 3. Valence State Determination.- 4. Optical Properties.- 5. Spin State Equilibria.- 6. Influences of Symmetry upon the Energy Levels of Low- and High-Spin States.- 7. Ligand Hyperfine Effects in Ferric Hemeproteins.- 8. Iron Hyperfine Effects.- 9. Modified Hemes.- 10. Photodissociation and Recombination.- 5 Nonheme Iron and Molybdenum.- 1. Iron Storage and Transport Proteins.- 2. Iron-Sulfur Proteins.- 3. Molybdenum.- 6 Electronic Structures and Properties.- 1. Atomic Orbitals.- 2. Spin States.- 3. Transition Metal Ions.- 4. Ligands and Molecular Orbitals.- 5. Absorption of Light.- 6. Interaction of Transition-Metal Ions with an Applied Magnetic Field.- 7. Magnetic Interactions of the Metal Electrons with Nuclei in the Coordination Sphere.- 8. Optical Activity.- References.