PREPARATION 211 



clature suggested by Pauling and Coryell {cf. Table I) will be used, which 

 denotes ferrous and ferric compounds by the prefixes ferro and ferri, respec- 

 tively. 



We have been tempted to adopt Drabkin's procedure of using a terminal 

 "an" to denote denaturation of protein. Denatured globin ferroprotopor- 

 phyrin would thus become mercifully abbreviated to "hemogloban." Our 

 decision against this usage has been influenced by several reasons. "Globan" 

 has been suggested for a number of years without finding application by 

 many workers. This may be due to the fact that the ending "an," while 

 having no chemical significance nevertheless suggests a definite and unique 

 chemical nature. It is doubtful whether the product of a process so com- 

 plicated and variable as is protein denaturation should be given such a name. 

 It would be necessary, anyhow, to distinguish between the "hemogloban" 

 resulting from irreversible, and that resulting from reversible, denaturation. 

 Finally, as long as readers are still unfamiliar with the hemo-hemi distinction, 

 watching for a second vowel in the word and distinguishing between hemo- 

 globin, hemogloban, hemoglobin and hem?globan would certainly confuse 

 them (as well as the printer). 



Table I presents the nomenclature that will be used in the present 

 work, together with the older nomenclatures of Keilin {H75) and 

 Pauling and Coryell {2127). Figure I indicates briefly the inter- 

 relationships of the different hemoglobin derivatives. 



2. PREPARATION AND PROPERTIES 



2.1. Preparation 



2.1.1. Oxyhemoglobin. Since this pigment is the starting point for 

 most work on the chemistry of hemoglobin derivatives, numerous 

 methods are available for its preparation from blood in a pure state. 

 For most purposes, the criteria of a good preparation are: complete 

 solubility in the pH range 5 to 9, freedom from contamination by 

 stroma debris, and finally the minimum amount of hemiglobin. 



The first step consists of removal of the plasma protein by repeated 

 centrifugation in isotonic or slightly hypertonic solution. The next 

 step is hemolysis of the corpuscles, which may be carried out by 

 alternate freezing and thawing, addition of minimal quantities of 

 distilled water, or by treatment with organic solvents such as toluene 

 or ether. The latter reagents denature and coagulate the stroma 

 proteins and lipides with minimal effect on the hemoglobin. Alter- 

 natively, the stroma may be precipitated after hemolysis by distilled 

 water by adjusting the pH to 6.5 and allowing the solution to stand 



