322 VII. COMPARATIVE BIOCHEMISTRY OF HEMOGLOBINS 



within a species (14-56,256Jf.,2807y2845) and in differences in amino 

 acid content (50,121,1639,2303,2437) are based on dubious experi- 

 mental grounds. In one case analysis was carried out on electro- 

 phoretically homogenous components; Reiner and co-workers {2229) 

 found native globin to contain 0.61 ± 0.02% sulfur. On electro- 

 phoresis between pH 2.6 and 3.7, they found two components and 

 succeeded in analyzing the faster. The sulfur content was 0.78 ± 

 0.03%. Since the nitrogen contents of the original protein and of 

 the faster fraction were identical, this difference in sulfur content is 

 significant. 



6.2.4. Spectroscopy and AfRnity for Gases. During the first phase of the 

 investigation of the dissociation curve of oxyhemoglobin, differences were 

 claimed to exist between the affinities of the blood of different adult individ- 

 uals for oxygen [HI). There appears to be a sliglit, probably significant differ- 

 ence between tlie affinity of the blood of normal men and women (JOdJSl])* 

 Differences have also been claimed between the equilibrium constant, A', for 

 the equation (HbC0)/(Hb02) = Kipco)/ (po,) ■ Sendroy, Liu, and van 

 Slyke [2533) considered that earlier claims for such variations of the latter 

 ratio (c/. GJ^.,1101) were due to technical faults, since repetition of the work 

 with manometric methods failed to show differences in human and ox blood, 

 outside the experimental error. Kiliick {1531 J532) more recently found in- 

 dividual differences for A' in mice. She used a Hartridge reversion spectro- 

 scope for the measurement of the band position of carboxyhemoglobin, a 

 method which is less accurate than manometric methods. In addition, she 

 worked with young mice in which fetal pigments may still be present. 



The most recent claim that differences are found in the spectra of pigments 

 from different individuals is that of Fox {03()). By correctly controlled 

 observations with the Hartridge reversion spectroscope, he found significant 

 differences in the position of the a band of oxyhemoglobin from individual 

 rabbits. No differences were found between the pigments from individual 

 earthworms, frogs, or humans. Although Fox worked with the dilute 

 hemolyzate from washed rabbit cells, this treatment is not sufficient to 

 remove possible interfering substances from hemoglobin (rf. Section 7.). 



7. MICROENVIRONMENT OF OXYGEN CARRIERS 



7.1. Extracellular Carriers 



The presence of a cell wall enables the pigment to exist in an environment 

 differing considerably from that provided by the circulating fluid. We 

 might also consider the possibility that the large molecules of the extra- 

 cellular erythrocruorins ^re similarly affected by the presence of other mole- 

 cules which are more or less firmly bound to them, thus creating a special 

 environment. The sedimentation constant, .S,o X 10' 3, of the erythrocruorin 



* This has, however, not heen confirmed {cj. ',}'J5,15-J.'ib). 



