Team:Imperial College London/Stomach

From 2009.igem.org

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=<b>Human Digestive Proteases:</b>=
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=<b>The Stomach & Proteolysis:</b>=
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The stomach serves to break large proteins into peptides. These peptides are then broken down into amino acids once they enter the duodenum.
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[[Image:Digestivesystem.jpg|100px|left]]
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* Pepsin = stomach
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* Trypsin = duodenum
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* Chymotrypsin
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* Carboxypeptidase
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The stomach is the first point at which polypeptides are broken down. It is here that large polypeptides are broken down into peptides. This process broadly involves two steps. First polypeptides are denatured by stomach acid, which causes them to open up. Subsequently, these denatured polypeptides are attacked by the protease 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. Small peptides leaving the stomach are later broken down into amino acids once they enter the duodenum.
{{Imperial/09/Division}}
{{Imperial/09/Division}}
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==Stomach==
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===The Stomach Simulator===
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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.
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One of the enzymes that we are showcasing is phenylalanine hydroxylase (PAH) (as a treatment for PKU). If this enzyme was simply swallowed in an unencapsulated form it would be cleaved in 146 places by pepsin in the stomach.  
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===Pepsin===
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Click on the <i>perform</i> button to see a simulated digestion of PAH by pepsin. Alternativly, paste in your own sequence into the box below to see if it would be a good candidate for encapsulation.  
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* Released by chief cells in the stomach.
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* Expressed as a zymogen pepsinogen.
 
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* Pepsinogen is converted to pepsin by HCl which is released by parietal cells of the stomach.
 
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* Cleaves at the N-terminus after aromatic amino acids such as phenylalanine, tryptophan, and tyrosine.
 
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* Optimum pH of 1.5 to 2. Pepsin denatures when the pH is more than 5.0.
 
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{{Imperial/09/Division}}
 
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=Peptide cutter=
 
<html>
<html>
<body>
<body>
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<!-- ********************************************************************************************** -->
 
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<!-- START OF HEADER information on top of the page -->
 
<div id='sib_container'>
<div id='sib_container'>
   <div id = 'sib_body'>     
   <div id = 'sib_body'>     
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  <b>PeptideCutter</b> [<A HREF="http://www.expasy.ch/tools/peptidecutter/tools/peptidecutter/peptidecutter_references.html">references</A> /
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   <form method=POST action="http://www.expasy.ch/cgi-bin/peptidecutter/peptidecutter.pl" target="_blank">
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  <A HREF="http://www.expasy.ch/tools/peptidecutter/tools/peptidecutter/peptidecutter_instructions.html">documentation</A>]
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   <textarea name="protein" rows=5 cols=50>Met S T A V L E N P G L G R K L S D F G Q E T S Y I E D N C N Q N G A I S L I F S L K E E V G A L A K V L R L F E E N D V N L T H I E S R P S R L K K D E Y E F F T H L D K R S L P A L T N I I K I L R H D I G A T V H E L S R D K K K D T V P W F P R T I Q E L D R F A N Q I L S Y G A E L D A D H P G F K D P V Y R A R R K Q F A D I A Y N Y R H G Q P I P R V E Y Met E E E K K T W G T V F K T L K S L Y K T H A C Y E Y N H I F P L L E K Y C G F H E D N I P Q L E D V S Q F L Q T C T G F R L R P V A G L L S S R D F L G G L A F R V F H C T Q Y I R H G S K P Met Y T P E P D I C H E L L G H V P L F S D R S F A Q F S Q E I G L A S L G A P D E Y I E K L A T I Y W F T V E F G L C K Q G D S I K A Y G A G L L S S F G E L Q Y C L S E K P K L L P L E L E K T A I Q N Y T V T E F Q P L Y Y V A E S F N D A K E K V R N F A A T I P R P F S V R Y D P Y T Q R I E V L D N T Q Q L K I L A D S I N S E I G I L C S A L Q K I K Stop</textarea>
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    predicts potential cleavage sites cleaved by proteases or chemicals in a given protein
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    sequence. 
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    PeptideCutter returns the query sequence with the
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    possible cleavage sites mapped on it and /or a table of cleavage site positions.
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  <P>
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   <form method=POST action="http://www.expasy.ch/cgi-bin/peptidecutter/peptidecutter.pl">
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    Enter a UniProtKB (Swiss-Prot or TrEMBL) protein 
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    identifier, ID (e.g. ALBU_HUMAN), or accession number, AC (e.g. P04406),
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  <B>or </B> an amino acid sequence (e.g. 'SERVELAT'):<BR>
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   <textarea name="protein" rows=12 cols=50></textarea><P>
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   <input type="submit" value="Perform"> the cleavage of the protein.
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   <input type="submit" value="Perform">  
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  <input type="reset" value="Reset"> the fields.<P>
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  <hr>
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   <input type=hidden name=enzyme_number value= less_enzymes checked>
   <input type=hidden name=enzyme_number value= less_enzymes checked>
   <input type=hidden name=enzyme  value=Pn1.3 checked>
   <input type=hidden name=enzyme  value=Pn1.3 checked>
   <input type=hidden checked name=cleavage_map value=cleavage_map>
   <input type=hidden checked name=cleavage_map value=cleavage_map>
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<select name="block_size"  size=1 style="display:none">
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  <option selected value= "60" selected>
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</select>
   <input type=hidden name=alphtable checked value=alphtable>
   <input type=hidden name=alphtable checked value=alphtable>
   <input type=hidden name=cleave_number checked value=all>  
   <input type=hidden name=cleave_number checked value=all>  
   </form>
   </form>
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  <HR>
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<br><A HREF="http://www.expasy.ch/tools/peptidecutter/tools/peptidecutter/peptidecutter_references.html">references</A> /<A HREF="http://www.expasy.ch/tools/peptidecutter/tools/peptidecutter/peptidecutter_instructions.html">documentation</A>  
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</div>
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</div> <!-- sib_body -->
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<!-- ********************************************************************************************** -->
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<!-- START OF FOOTER information at the bottom of the page -->
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<div id = 'sib_last_update'></div>
<div id = 'sib_last_update'></div>
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<div id = 'sib_footer'> </div>
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<div id = 'sib_footer'> </div>
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</div>
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<!-- END OF FOOTER -->
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<!-- ********************************************************************************************** -->
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</div> <!-- sib_container -->
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</body>
</body>
</html>
</html>
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<html><center><a href="https://2009.igem.org/Team:Imperial_College_London/M2"><img width=150px src="https://static.igem.org/mediawiki/2009/1/10/II09_TourArrow.png"></a>
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</html>
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{{Imperial/09/TemplateBottom}}
{{Imperial/09/TemplateBottom}}

Latest revision as of 23:30, 19 October 2009

The Stomach & Proteolysis:

Digestivesystem.jpg

The stomach is the first point at which polypeptides are broken down. It is here that large polypeptides are broken down into peptides. This process broadly involves two steps. First polypeptides are denatured by stomach acid, which causes them to open up. Subsequently, these denatured polypeptides are attacked by the protease 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. Small peptides leaving the stomach are later broken down into amino acids once they enter the duodenum.


The Stomach Simulator

One of the enzymes that we are showcasing is phenylalanine hydroxylase (PAH) (as a treatment for PKU). If this enzyme was simply swallowed in an unencapsulated form it would be cleaved in 146 places by pepsin in the stomach.

Click on the perform button to see a simulated digestion of PAH by pepsin. Alternativly, paste in your own sequence into the box below to see if it would be a good candidate for encapsulation.


references /documentation



Mr. Gene   Geneart   Clontech   Giant Microbes

Retrieved from "http://2009.igem.org/Team:Imperial_College_London/Stomach"