CONTENTS XIX 



3.4 Cytochromes h 358 



3.5 Cytochrome a •'^^'^ 



3.6 The Respiratory Ferment and (Cytochromes Related to It. . .362 



.S.6.1 Respiratory Ferment 36^2 



3.6.2 Inhibitors '^^'J 



3.6.3 Cytochrome ai '565 



3.6.4 Cytochrome Oxidase 366 



3.6.5 Cytochrome as 367 



3.6.6 Cytochrome aa 370 



4 "Pasteur Enzyme" 371 



5 Biological Function of the Cytochrome System 373 



5.1 Introduction 373 



5.2 Pathways of Cellular Oxidation through the Cytochrome 

 System 374 



5.3 The Cytochrome System in V'arious Organisms 377 



5.3.1 Cytochrome c and Cytochrome Oxida.se in Animal 

 Tissues 377 



5.3.2 The Cytochrome System of Plants 379 



5.4 Study of Respiration by Inhibitors 379 



5.5 Importance of the Cytochrome System for Supply of Energy 



and Cell Function 383 



6 Theory of Mode of Action of the Respiratory Ferment 384 



6.1 Autoxidation 384 



6.2 Radical Chain Theory 386 



6.3 Hemoglobin as a Cytochrome Oxidase Model 388 



6.3.1 Introduction 388 



6.3.2 Hem/globin Formation 389 



6.3.3 Oxidation of Groups in Globin 390 



6.3.4 Formation of Hem/globin by Reducing Substances 



in the Presence of Oxygen 391 



6.3.5 Autoxidation of Hemoglobin 392 



6.3.6 Oxidizing Action of Oxygen Liberated from Oxy- 

 hemoglobin 395 



6.4 Mode of Action of the Respiratory Enzyme 397 



IX. Hematin Enzymes, II 401 



1 Introduction "^^l 



1.1 Historical 401 



1.2 Model Reactions with Simple Hematin Compounds 402 



1.2.1 Catalatic Activity 402 



1.2.2 Peroxidative Activity 402 



2 Catalase 403 



2.1 Isolation 403 



2.2 Spectroscopic and Magnetochemical Properties of Catalase 



and Compounds of Catalase 405 



2.3 Inhibitors 409 



2.4 Estimation and Enzyme Kinetics 410 



2.5 Nature of the Prosthetic Group 413 



2.6 Protein of Catalase . . .• 414 



2.7 Biological Function of Catalase 415 



2.7.1 Occurrence of Catalase 415 



2.7.2 Protection against Hydrogen Peroxide 416 



2.7.3 Catalase as a' Peroxidative Enzyme 417 



