XIV CONTENTS 



9 Estimation of Bile Pigments 153 



9.1 Estimation of Bilirubin 153 



9.2 Estimation of Urobilin and Urobilinogen 156 



V. Hematin Compounds 159 



1 Basis of Metal Complex Formation 159 



1.1 Stereochemistry of Complex Formation 159 



1.2 Bond Type in Metal Complexes 160 



1.3 Absorption Spectrum and Bond Type 162 



2 Nomenclature 163 



3 Hemes, Hemins, and Hematins 166 



3.1 Hemes 166 



3.2 Hemins 167 



3.3 Hematins 169 



4 Hemochromes and Hemi'chromes 174 



4.1 Hemochromes 174 



4.1.1 Affinity of Heme for Bases 174 



4.1.2 Stereochemistry of Base Combination 176 



4.1.3 Absorption Spectra 176 



4.2 Hemochromes 177 



4.2.1 Stability of Hemzchromes 177 



4.2.2 Bond Type in Hemochromes 178 



4.2.3 Composition and Structure 178 



4.2.4 Affinity of Hematin for Bases 182 



4.2.5 Absorption Spectra 183 



5 Combination of Hematin Compounds with Oxygen, Hydrogen 

 Peroxide, Carbon Monoxide, and Cyanide 184 



5.1 Compounds with Oxygen and Hydrogen Peroxide 184 



5.2 Carbon Monoxide Compounds 185 



5.2.1 Carbon Monoxide Heme 185 



5.2.2 Carbon Monoxide Hemochromes 185 



5.3 Cyanide Compounds 187 



5.3.1 Dicyanide Ferriporphyrin 187 



5.3.2 Cyanide Ferroporphyrins 188 



5.3.3 Mixed Cyanide-Base Hematins 190 



5.3.4 Absorption Spectra of Cyanide Compounds 191 



5.3.5 Linkage of Cyanide 191 



5.4 Other Compounds of Heme and Hematin 191 



6 Metalloporphyrins Containing Nickel, Cobalt, and Manganese 192 



7 Oxidation-Reduction Potentials of Hematin Compounds 193 



7.1 Oxidation-Reduction Potentials at Constant pH 193 



7.1.1 The Heme-Hematin System 193 



7.1.2 Systems Involving Coordinating Substances 194 



7.1.3 Determination of Constitution of Hemochromes .. . 196 



7.2 Influence of pH 197 



7.3 Influence of BuflFer Anions 201 



8 Hematin Compounds of Aza- and Oxyporphyrins and Other Hematin 

 Compounds 201 



8.1 "Red, Red-Green, and Green Hemins" 201 



8.2 Monoazahematin Compounds 202 



8.3 Oxyporphyrin Hematin Compounds 203 



8.4 Hematins c 203 



