From Proteopedia

Revision as of 18:04, 28 October 2010

Trypsin

Trypsin is a serine protease that is produced in the pancreas. Serine protease means that it is an enzyme that cleaves amino acid sequences and that a serine residue is located in the active site of the enzyme. In order to prevent it from breaking down the proteins in the pancreas of the organism that produces it, it is first produced as the inactive zymogen, proenzyme trypsinogen.

Structural Aspects

Trypsin is an enzyme that is composed of one, sequence unique, chain consisting of 58 amino acid residues. Looking at the of trypsin one can see it is composed of two alpha helices(pink) and two beta sheets(yellow).

Observing the of trypsin one can easily follow the primary sequence of the amino acids as it begins at the amide or N-terminal end(dark blue), and progresses to the carboxyl or C-terminal end with the final 58th amino acid reside (red).

Trypsin is held together by three located between the 5 and 55, 14 and 38, and 30 and 51 Cystine residues(yellow). Besides disulphide bonds, another major force that holds an enzymes structure together is hydrogen bonding. Looking first at the one can begin to see the importance of hydrogen bonds in the alpha helices and beta sheets. Looking at the in the side chains, it one can see how it further serves to stabilize these secondary structures. A salt bridge holds the N and C terminal ends together, further stabilizing the protein.

To determine the polar and non-polar sections of an enzyme, the various R groups coming off of the are analyzed. Looking at the , the side chains can be classified as either non-polar otherwise known as hydrophobic (literally meaning water fearing) or polar otherwise known as hydrophilic (water loving). Looking first at the you can easily see the classifications of the nonpolar(pink) and polar(yellow) side chains. Looking at this molecule you can see the majority of the yellow strands are found near the exterior of the enzyme where they would act with the polar environment, while many of the nonpolar residues are hidden inside. Looking at the model you can achieve a better grasp on the organization of these nonpolar and polar sections of the enzyme. Polar regions again appear in yellow, nonpolar pink, and some of the waters that would interact with the enzyme appear gray in the diagram.

Looking at the structure you will notice three SO4 molecules and a single SO2 (sulfur yellow, oxygen red). This play no part in the function or role of the enzyme but were simply used to help stabilize the protein for crystallization so its three dimensional structure could be recorded and analyzed.

Function

In biological applications trypsin is used to cleave and break down proteins. Due to the nature of trypsin's it cleaves on the C-terminal(or carboxyl) end of lysine and arginine amino acid residues, except when this C-terminal end is attached to proline (as its rigid structure sterically inhibits the enzyme). The yellow ball and stick residues show the active site, while the green shows an aspartic acid residue. As aspartic acid is deprotonated at physiological pH it carries a negative charge and easily attracts the lysine and arginine positive residues which trypsin cleaves.

Medical Importance and Other Applications

Cystic Fibrosis is a disease in which the body fails to properly transport trypsin and other enzymes from the pancreas.

Imbalances of trypsin and other related proteins are believed to play a role in disorders like emphysema, asthma, arthritis, skin disorders, and cancerous tumor growth.

Trypsin is used with a combination of bromelain and rutin to relieve pain and improve function joint for individuals suffering from osteoarthritis.

Trypsin is used in wound cleansing and healing as it helps remove dead tissue and improve healing time.

Trypsin is added to baby food to help pre-digest the proteins to help babies digest it.

Trypsin is also used as a digestion aid to help individuals who lack enzymes needed for digestion.