III. CENTRIFUGATION 95 



TABLE I 



Molecular Constants of Some Serum Proteins" 



Protein 526 D20 F20 Mol. wt. ///» 



Fetuin 



Calf 3.28-0.0020 X An'' 5.5 O.7I4 50,600 1.60 



Cow fetus 3.09-0.0015 X Am 5.0 0.69-2 48,700 1.80 



Cow fetus 3.23-0.0020 X An (5.5) O.7I2 49,500 1.61 



Serum albumin 



Human 4.6-0.0022 X An 5.9 0.736 72,300 1.30 



Cow fetus 4.7-0.0019 X Am 6.4 (0.736) 67,800 1.21 



Globulin 



Cow7-globulin 



Pii5i 7.4-0.0040 X An 3.7 (0.732) 180,000 1.52 



gi8y 7.6-0.0025 X An 3.5 0.73. 192,000 1.56 



gi5s 7.6-0.0029 X An 3.8 (0.732) 182,000 1.49 



Human 7-glob- 

 ulin 7.1-0.0034 X An 4.0 0.718 153,000 1.51 



Anticomple- 

 mentary hu- 

 man pseudo- 

 globulin.... 7.1 3.8 0.732 170,000 1.53 



W-co7nponents 

 Isohemagglu- 



tinin, human 19.8-0.0074 X An ... (0.73) (~5 X 10^1 



Pathological 

 human eu- 

 globulin 



From/37.... 19. 1-0.022 X An >1.4\ 0.73,, ~1.2X10« 2.1 



From/39... 19.5-0.022 X An <1.6/ (0.733) '-'11.2X10'= 2.0 

 X-protein 



Human 5.9 1.7 0.96/ ('-^2 X 10«)'^ .. 



" After Pedersen (38). S20 values are in Svedberg units and D.o values are in 

 units of 1 X 10-'. 



^ For most serum proteins, An equals approximately 189 times the concentra- 

 tion of protein in per cent. 



" For the hydrated particle. 



tained by separate diffusion experiments. There is an increase in 

 boundary sharpness with increasing concentration in the case of ultra- 

 centrifugation and, for the most precise work, results must be extra- 

 polated to zero concentration or some allowance must be made. 

 AVith experience, one learns to recognize immediately by inspection 

 of the photographs any appreciable inhomogeneity. The sharpening 

 with concentration is sometimes actually an advantage, in that it per- 

 mits greater resolution of components to be obtained. The amount 



