28 UNITY AND DIVERSITY IN BIOCHEMISTRY 



Table VI {continued) 



L (+) Phenylalanine (Phe), a-amino-jS-phenylpropionic acid 



R = benzyl (Ar, N, NP, NI) 



NHa 



CH,-CH-COOH 



L (— ) Proline (Pro), pyrrolidine-2-carboxylic acid 



R = — (He, N, NP, NI) HoC CHj 



I I 



H2C C— COOH 



\ /H 



N 

 H 



L (— ) Serine (Ser), a-amino-j3-hydroxypropionic acid 



NH2 



I • 

 R = hydroxymethyl (Al, N, P, NI) HO— CH2— CH— COOH 



L (— ) Threonine (Thr), a-amino-jS-hydroxybutyric acid 



NH2 



I 

 R = hydroxyethyl (Al. N. P, NI) CH3-CH-CH-COOH 



OH 



L (— ) = Tryptophan'(Try), a-amino-j8(3)-indolepropionic acid 



NH2 



I 



/\ n -CHa-CH-COOH 



P a 



R = skatolyl (He, Ar, N, NP, NI) 



NA. 



H 



L (— ) Tyrosine (Tyr), a-amino-^(p-hydroxyphenyl) propionic acid 

 R = /)-hydroxybenzyl (Ar, N, FP, FI) 



NH2 



HO-C >-CH2-CH-COOH 



L (— ) Valine (Val), a-aminoisovaleric acid CH3 NHo 



\ I 



CH— CH-COOH 



R = isopropyl (Al, N, NP, NI) ^{^ 



CH3 



