Revision as of 12:15, 2 October 2009

Human Digestive Proteases:

The stomach serves to break large proteins into peptides. These peptides are then broken down into amino acids once they enter the duodenum.

Pepsin = stomach

Trypsin = duodenum

Chymotrypsin

Carboxypeptidase

Stomach

The stomach is the first point at which polypeptides are broken down. The low pH of the stomach causes enzymes to denature, opening them up to attack from proteases such as pepsin.

Pepsin

Pepsin is a powerful protease that cleaves at the N-terminus after aromatic amino acids such as phenylalanine, tryptophan, and tyrosine. The optimum pH of pepsin is from 1.5 to 2, at a pH of above 5 denaturation occurs. This means that pepsin is only functional in the acidic environment of the stomach.

One of the enzymes that we are showcasing The E.ncapsulator with is phenylalanine hydroxylase (PAH) as a treatment for PKU. If this enzyme was simply swallowed in an unencapsulated form it would be rapidly broken down byb pepsin in the stomach.

references /documentation

Duodenum

Endopeptidases (trypsin, chymotryopsin, elastase) Exopeptidases (carboxypeptidases A & B) Enteropeptidase

Trypsin

Trypsin is found in the duodenum and serves to hydrolyse peptides into amino acids.
Trypsin has an optimal operating pH of ~8 and an optimum temperature of 37°C.
Trypsin breaks down the milk protein casein. For this reason, milk protein would be a good protein to use for secondary encapsulation.

Chymotryopsin

Elastase

Enterokinase

Carboxypeptidases A & B

Small Intestine = Aminopeptidase N Dipeptidyl aminopeptidase IV Aminopeptidase P Carboxypeptidase P Angotensin-converting enzyme Glutamyl aminopeptidase

@@ Line 23: / Line 23: @@
 ===Pepsin===
-* Released by chief cells in the stomach.
+Pepsin is a powerful protease that cleaves at the N-terminus after aromatic amino acids such as phenylalanine, tryptophan, and tyrosine. The optimum pH of pepsin is from 1.5 to 2, at a pH of above 5 denaturation occurs. This means that pepsin is only functional in the acidic environment of the stomach.
-* Expressed as a zymogen pepsinogen.
+One of the enzymes that we are showcasing The E.ncapsulator with is phenylalanine hydroxylase (PAH) as a treatment for PKU. If this enzyme was simply swallowed in an unencapsulated form it would be rapidly broken down byb pepsin in the stomach.
-* Pepsinogen is converted to pepsin by HCl which is released by parietal cells of the stomach.
-* Cleaves at the N-terminus after aromatic amino acids such as phenylalanine, tryptophan, and tyrosine.
-* Optimum pH of 1.5 to 2. Pepsin denatures when the pH is more than 5.0.
-=Peptide cutter=
-If you want to see the effect of the protease pepsin, please enter the amino acid sequence of a polpeptide into the table below.
-Why not try the sequence for phenylalanine hydroxylase (PAH); one of the enzymes that we are delivering to the GI tract.
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Team:Imperial College London/Stomach

From 2009.igem.org