<P> Pepsin is most active in acidic environments between 37 ° C and 42 ° C. Accordingly , its primary site of synthesis and activity is in the stomach ( pH 1.5 to 2 ) . Pepsin will digest up to 20 % of ingested amide bonds by cleaving preferentially at the N - terminal side of aromatic amino acids such as phenylalanine , tryptophan , and tyrosine . Pepsin exhibits preferential cleavage for hydrophobic , preferably aromatic , residues in P1 and P1 ' positions . Increased susceptibility to hydrolysis occurs if there is a sulfur - containing amino acid close to the peptide bond , which has an aromatic amino acid . Pepsin cleaves Phe Val , Gln His , Glu Ala , Ala Leu , Leu Tyr , Tyr Leu , Gly Phe , Phe in the insulin B chain . Pepsin exhibits maximal activity at pH 2.0 and is inactive at pH 6.5 and above , however pepsin is not fully denatured or irreversibly inactivated until pH 8.0 . Therefore , pepsin in solution of up to pH 8.0 can be reactivated upon re-acidification . The stability of pepsin at high pH has significant implications on disease attributed to laryngopharyngeal reflux . Pepsin remains in the larynx following a gastric reflux event . At the mean pH of the laryngopharynx ( pH = 6.8 ) pepsin would be inactive but could be reactivated upon subsequent acid reflux events resulting in damage to local tissues . </P>
<P> Pepsin is most active in acidic environments between 37 ° C and 42 ° C. Accordingly , its primary site of synthesis and activity is in the stomach ( pH 1.5 to 2 ) . Pepsin will digest up to 20 % of ingested amide bonds by cleaving preferentially at the N - terminal side of aromatic amino acids such as phenylalanine , tryptophan , and tyrosine . Pepsin exhibits preferential cleavage for hydrophobic , preferably aromatic , residues in P1 and P1 ' positions . Increased susceptibility to hydrolysis occurs if there is a sulfur - containing amino acid close to the peptide bond , which has an aromatic amino acid . Pepsin cleaves Phe Val , Gln His , Glu Ala , Ala Leu , Leu Tyr , Tyr Leu , Gly Phe , Phe in the insulin B chain . Pepsin exhibits maximal activity at pH 2.0 and is inactive at pH 6.5 and above , however pepsin is not fully denatured or irreversibly inactivated until pH 8.0 . Therefore , pepsin in solution of up to pH 8.0 can be reactivated upon re-acidification . The stability of pepsin at high pH has significant implications on disease attributed to laryngopharyngeal reflux . Pepsin remains in the larynx following a gastric reflux event . At the mean pH of the laryngopharynx ( pH = 6.8 ) pepsin would be inactive but could be reactivated upon subsequent acid reflux events resulting in damage to local tissues . </P>
where does pepsin work in the digestive system
where does pepsin work in the digestive system
the stomach
the stomach