iv THE HEMI- AND ANTI-GROUPS 153 



Formerly it seemed as if albumins differed greatly from one an- 

 other because of the way in which the individual groups were arranged 

 in the molecule, but with the improvements in our methods of pre- 

 paring dissociation -products these supposed differences have become 

 less and less. Since Kossel made us acquainted with reliable methods 

 for preparing lysin, arginin, and histidin, arginin has been found in all, 

 and lysin and histidin in nearly all, albuminous substances. With E. 

 Fischer's new methods only a few albumins have been examined, but 

 these show a remarkable similarity. Even silk-fibroin with its entirely 

 different configuration has been brought nearer to the other albumins, 

 and the same holds good for gelatine and for keratin. Edestin, globin, 

 and serum -albumin show even quantitatively the greatest similarity. 

 Therefore differences in albumins are not so much dependent on differ- 

 ences in the building material as on the material being used in 

 different amounts and in different arrangements. The amounts are 

 very different, as most of the dissociation-products do not occur once 

 but several times in the albumin-molecule. Comparing, for example, 

 leucin arid histidin with tyrosin, we find that globin must contain at 

 least 32 leucin and 10 histidin molecules. Calculations based on 

 analytical data show the molecular weight of haemoglobin to be at least 

 16669; if this figure is correct, then haemoglobin must contain at 

 least 36 molecules of leucin and 12 molecules of histidin. Deter- 

 minations of the amount of ammonia contained in gelatine show, 

 analogously, that gelatine must contain 8 molecules of glycocoll, while 

 the amount of histidin in edestin is equivalent to 12 molecules of 

 leucin and 6 molecules of arginin. Kossel and Dakin l give the 

 following figures for salmin : For every 1 molecules of di-amino- 

 valerianic acid are found 10 molecules of urea, 2 molecules of serin, 

 1 molecule of mono-amino-valerianic acid, and 2 molecules of pyrrolidin- 

 carboxylic acid. 



That one and the same substance may occur in different combina- 

 tions has been shown by E. Fischer and Abderhalden, who found 

 leucin, alanin, glutaminic and aspartic acids both in the anti- and in 

 the hemi-group. 



Now arises the question : What grouping of atoms have we to con- 

 sider as typical of albumins ? a question which, if we can answer it, will 

 define and accurately outline the group of albuminous substances. 



The most important grouping, without doubt, is the union of 

 a-amino-acids to form acid-imines, and therefore such bodies as glycyl- 

 glycin and its homologues may be taken as the simplest of all albumins. 



1 Kossel, Berliner klin. Wochenschrift, No. 41, October 1904, p. 1065. 



