XVlll CONTENTS 



5.2.1 Invertebrate Oxygen Carriers 315 



5.2.2 Vertebrate Oxygen Carriers ; 315 



5.2.3 Myohemoglobin 317 



5.3 Solubility . .' 318 



5.4 Other Protein Reactions 319 



6 Variation of Protein within a Species 319 



6.1 Ontogenetic Variation 319 



6.1.1 Fetal Hemoglobin 319 



6.1.2 Alkali Resistance 319 



6.1.3 Amino Acid Composition 320 



6.1.4 Size and Shape 320 



6.2 Intraspecific Variation — Adult Pigments 321 



6.2.1 Methods 321 



6.2.2 Alkali Resistance 321 



6.2.3 DifiFerences in Composition 321 



6.2.4 Spectroscopy and AflBnity for Gases 322 



7 Microenvironment of Oxygen Carriers 322 



7.1 Extracellular Carriers 322 



7.2 Erythrocyte 323 



7.2.1 Concentration of Hemoglobin 323 



7.2.2 Spectrum of Hemoglobin within the Erythrocyte . . 323 



7.2.3 Oxygen Affinity 323 



7.3 Myohemoglobin in the Muscle Cell 324 



8 Bases of Adaptation 324 



8.1 Environment of the Oxygen Carriers 324 



8.2 Mechanisms 326 



8.2.1 Variation of the Heme 326 



8.2.2 Variation of the Protein 326 



8.2.3 Variation of Microenvironment 326 



9 Functional Adaptation — Mammalian Respiration 327 



9.1 Significance of Sigmoid Dissociation Curve 327 



9.2 Interaction between Oxygen and Carbon Dioxide Transport 328 



9.3 Fetal Respiration 329 



10 Functional Adaptation — Myohemoglobin 330 



11 Functional Adaptation — Submammalian Pigments 331 



11.1 Diversity of Environments 331 



11.2 Adaptation to Low Pressure of Oxygen 332 



11.3 Role of Absolute Reaction Velocities 334 



11.4 Store or Carrier.^ 335 



VIII. Hematin Enzymes, I. The Cytochrome System 337 



1 Introduction 337 



2 Simple Hematin Compounds as Oxidative Catalysts 341 



3 The Cytochrome System 343 



3.1 Introduction 343 



3.2 Spectroscopic Observations on Cytochromes. 344 



3.3 Cytochrome c 347 



3.3.1 Isolation, Properties, and Estimation 347 



3.3.2 Nature of the Active Center of Cytochrome c and 



Its Linkage to Protein 350 



3.3.3 Protein of Cytochrome c 356 



