168 BREAKDOWN OF NITROGENOUS MATERIAL 



aspartic acid, and possibly tryptophan, but for no monamino- 

 monocarboxylic acids. In each case a simple decarboxylation 

 occurs with the production of the corresponding amine or, 

 with the dicarboxylic acids, of the a>-amino-acid. Any 

 alteration in the structure of the amino-acid such as methyla- 

 tion of either — NHg group in the diamino-acids, or of substi- 

 tution of the — OH in tyrosine, or the S-COOH in glutamic 

 acid, results in inactivation, since combination between the 

 decarboxylase protein and the substrate is thus prevented 

 (see Chap. III). The addition of — OH to the substrate such as 

 occurs in hydroxy lysine, dihydroxy tyrosine, or hydroxy- 

 glutamic acid slows down, but does not prevent, decarboxyla- 

 tion by the corresponding decarboxylase. 



H2N. /. H,N. 



>C— NHCH2.CH0.CH2.CHNH2. COO H > >C-NHCH2.CH2. 



HN^ " ' HN^ CH2.CH2NH2 



L-Arginine Agmatine 



H2N.CH2.CH2.CH2.CH2.CHNH2. ICOQIH > H2N.CH2.CH2.CH2.CH2. 



CH2NH2 



L-Lysine Cadaverine 



H2N.CH2.CH2.CH2.CHNH2. |coo|h — > H2N.CH2.CH2.CH2.CH2NH2 



L-Ornithine Putrescine 



/ 



HC=CCH,.CHNH2. ICOOIH HC=CCH2.CH2NH2 



I I ' > I 1 



N NH N NH 



Y Y 



H L-Histidine H Histamine 



H0<^~ VHo.CHNHo. ICOOIh > H0<;^~'^CH2.CH2NH, 



L-Tyrosine Tyramine 



__/ 



HOOC.CH2.CH2.CHNH2. |C00|H > HOOC.CH2.CH2.CH2NH2 



li-Glutamic acid y-Amino-butyric acid 



/ 



HOOC.CH2.CHNH2. |COO|H > HOOC.CH2.CH2NH2 



L- Aspartic acid j8-alanine 



