Transition Metals in Biochemistry: (26 Molecular Biology, Biochemistry and Biophysics Molekularbiologie, Biochemie und Biophysik)

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.

Table of 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.- 4. Molecular Functions of Proteins Containing Transition Metal Ion Prosthetic Groups.- 5. The Role Which a Transition Metal Ion Plays in the Function of a Protein.- 6. Experimental Methods.- 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.- 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.