AMYLOID 



423 



Quite similar analytic results have been obtained by Neuberg,'^ 

 who corroborated Krawkow's finding of a body of apparently similar 

 composition in tlie normal aorta. Neuberg has studied especially the 

 protein constituent of the amyloid compound, and found it character- 

 ized by a high proportion of diamino-nitrogen,"^ as compared with 

 most proteins, as shown in the following table giving the percentage 

 of the total N contained in each of the three forms, amid-nitrogen 

 (ammonia), monamino-acids, and diamino-acids: 



Tahle I 



Monamino- 



acid 



nitrogen 



Diamino- 



acid 

 nitrogen 



Amid 

 nitrogen 



Liver amyloid . . . . 

 Spleen amyloid . . . 

 Aorta "amyloid". 



Gelatin 



Casein 



43.2 

 30.6 

 54.9 

 62.5 

 76.0 



51.2 

 57.0 

 36.0 

 35.8 

 11.1 



4.9 



11.2 



8.8 



1.6 



13.4 



The variations in the composition of the different amyloids, as 

 shown in the above table, indicate that the protein group may vary in 

 different organs in different cases, and also indicate that the "amyloid- 

 like" substance of normal vessels is not the same as the pathological 

 substance. Corresponding variations were found in the apportion- 

 ment of the sulphur between that which is in the form of oxidized sul- 

 phur and the unoxidized sulphur. The proportion of the different 

 amino-acids in the protein constituent of amyloid is strikingl}' like that 

 of thjmius histon, and entirely dissimilar to the apparently closely 

 related elastin, as shown by Table II. 



Table II 



Cleavage products (in percentages) 



Amyloid 



Elastin 



Thymus 

 histon 



Glycocoll 0.8 ! 25.8 



Leucine 22.2 j 45.0 



Glutaminic acid 3.8 0.7 



Tyrosine 4.0 i 0.3 



a-Proline 3.1 1.7 



Arginine - 13.9 0.3 



Lj'sine 11.6 I .... 



0.5 



11.8 

 3.7 

 5.2 

 1.5 



14.5 

 7.7 



"Verh. Deut. Path. GeselL, 1904 (7), 19. 



^^ Corroborated by Jackson and Pearce (Jour. Exp. Med., 1907 (9), 520), but 

 not by Mayeda (Zeit. physiol., Cliem., 1909 (58), 469), who found histidine, which 

 Neuberg had missed, and a lower arginine and lysine content than histon re- 

 quires. 



