THE PROTEINS AND THEIR METABOLISM ill 



It does not give rise to acetone bodies. Its conversion into glucose in 

 all probability is also through a malic acid stage. 



coon COOH co,. 



''" Clio CIF :{ 



I 



CHOH CHOH > CHOH Glucose 



I I I 



CHXH, COOH COOII 



I 



coon 



fMiydroxyg'lutamic Malic Lactic 



acid acid acid 



Serin is converted into glucose, in all probability quantitatively. After 

 deamination it may give rise to glyceric acid, which is convertible into glu- 

 cose. (Dakin, Ringer and Lusk.) 



CHoOH CH 2 OH 



I I 

 CHNH 2 Deamination CHOH > Glucose 



COOH COOH 



Serin Glyceric acid 



Cyst in in the body is broken up into two molecules of cyst em. 

 OH., S S CH, CH 2 SH 



I I I 



CHNH 2 CHNH 2 >2 CHNH 2 



COOH COOH COOH 



Cystin Cystein 



Cystein may undergo deamination and desulphurization yielding a 

 three carbon compound which is completely converted into glucose (Dakin). 

 The intermediary products are, in all probability, similar to those of serin. 

 Cystein to a small extent may also undergo decarboxylation, giving 

 . -isf to thioethylamin, which on oxidation gives rise to taurin. 



CILSH CH 2 SH CH 2 SO 2 OH 



| Decarboxylation | Oxidation | 

 CHXIEo '- CH 2 NHo > CHoNH 2 



I 



COOH CO 2 



Cystein . Thioethylamin -Taurin 



'1 'his taurin is used by the liver cells to combine it with cholic acid, form- 

 in ir taurocholic acid, which is one of the bile salts. .This is therefore the 



