406 CHEMISTR V OF THE DIGESTIVE PROCESSES. 



closely resembling Meissner's parapeptone antialbumate ; considering 

 them anti bodies, from the fact that the} 7 do not yield leucine and 

 tyrosine on tryptic digestion, but are, though with difficulty (especially 

 in the case of antialburnid), converted into antipeptone. 



Klihne gave the following graphic representations of the cleavage of 

 proteids by acids and by digestion : 



Scheme of Proteid Cleavage ~by Acids. 

 ALBUMIN. 



Antigroup. Hemigroup. 



Autialbumid. 



Antialbumate. ^ 



Antialbnmose. Heniialbumose. 



Antipeptone. Heraipeptone. 



Scheme of Digestive Cleavage of Proteids. 



ALBUMIN 



(ALBUMINATE). 



| 



I ! 



r Autialbumose. Heniialbumose. 



Peptic J | . | 



Digestion A I.I I I Tryptic 



^. Autipeptone. Antipeptone. Hemipeptone. Hemipeptone. ^Digestion. 



Leucine. Tyrosine. Leucine. Tyrosine. 



Kiihne, in conjunction with Chittenden, 1 subsequently investigated 

 more minutely the intermediate products in peptic digestion, and those 

 formed by the action of dilute acids. The following is an account of 

 the substances obtained and their mode of preparation : 



Antiallumid. This substance was prepared as follows : The white of fifty 

 eggs, freed from membrane and much diluted, was made feebly acid with 

 sulphuric acid and coagulated by boiling. The coagulum was suspended in 

 1300 c.c. of water containing 7 c.c. of sulphuric acid and heated to 100 C. ; after 

 ten hours it appeared little altered and was filtered off. The filtrate gave on 

 neutralisation a precipitate principally composed of acid albumin. After 

 removal of the first acid, the albumin which had remained undissolved was 

 heated with 3 litres of J per cent, sulphuric acid to 100 C. for nineteen hours, 

 then collected on a filter and completely washed. 



The albumid thus obtained was insoluble both in dilute and concentrated 

 acetic acid, and in hydrochloric acid of 1'4 per mille and stronger, but easily 

 soluble in dilute caustic soda solution and in dilute alkaline carbonates, from 

 which it was precipitated by concentrated sodium chloride. Purified by diges- 

 tion with gastric extract, and 4 per mille hydrochloric acid for six hours at 

 40 C., it remained undissolved, but changed in appearance, becoming clotlike. 

 The clot was washed with water, dissolved in 1 per cent, solution of sodium 

 carbonate, filtered, reprecipitated with sulphuric acid, and washed again. It 

 now dissolved in 2 per mille hydrochloric acid, and in this solution was digested 

 with good peptic extract for eighteen hours. It was unchanged, and reappeared, 

 in equal amount to the eye, on neutralisation of the solution. 

 1 Ztsehr.f. Biol., Mlinchen, 1883, Bd. xix. S. 159. 



