Digestion  of proteins

Digestion  of proteins  is  initiated  in  the  stomach by pepsin.  Pepsin  acts upon food proteins  and  converts them  to proteoses  and  peptones which  are  large polypeptide derivatives as can  be  seen in  Figure.  Pepsin is  Ln  endopeptidase since  it hydrolyses  peptide  bonds within  the main polypeptide structure. Pepsin  specifically acts  upon  the  peptide  bonds formed  by  amino acids  with  an aromatic  ring =(e.g.  tyrosine)  or  dicarboxylic amino  acid  i.e.  amino acids with  2  COOH  groups (e.g.  glutamate).