Sandbox 37: Difference between revisions

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[[Image:Papaya.jpg | right| thumb| ''Carica papaya'']]

<scene name='Sandbox_37/Main_scene/1'>Papain</scene> is a cysteine protease that is stable and active under a wide range of conditions. The enzyme present in the leaves, latex, roots, and fruit of the papaya plant (''Carica papaya'').<ref>http://www.britannica.com/EBchecked/topic/441803/papain</ref> The papain proteins are synthesized as inactive precursors that become active within two minutes of the plant being wounded and the latex is expelled.<ref>http://www.worthington-biochem.com/pap/default.html</ref> The latex is dried and then purified to extract the active papain enzme. The enzyme was first studied and isolated in the 1960's. It has a 23.4kDa theoretical molecular weight and works at an optimum pH of 6-7 and optimum temperature of 60-70 degrees Celsius.

==Structure==

Papain's three-dimensional structure is at 1.65 Angstrom resolution. It consists of one polypepetide chain that is made up of 212 amino acids residues. There are three <scene name='Sandbox_37/Papain_disulfide_bonds/1'>disulfide bonds</scene> present in the enzyme that maintains the protein's structure. Papain consists of 25% alpha helices and 21% beta sheets within its <scene name='Sandbox_37/Papain_beta-alpha/1'>secondary structure</scene>. Alpha helices are shown in red and beta sheets are shown in green. The enzyme's structure has a mixture of <scene name='Sandbox_37/Papain_hydrophobic/7'>hydrophobic residues</scene> shown in yellow and hydrophilic residues shown in purple. This corresponds to the protein's <scene name='Sandbox_37/Papain_polar/1'>polar residues</scene> shown in orange and nonpolar residues shown in green. Papain is naturally found with many <scene name='Sandbox_37/Ligand/3'>ligands</scene>. The majority are methanol molecules because the crystallization medium is 62% (w/w) methanol in water and only 29 out of 224 solvent molecules can be regarded with any certainty as methanol molecules.<ref>http://www.pdb.org/pdb/explore.do?structureId=9PAP</ref> Here, the enzyme's sulfhydryl group can also be seen which is necessary for the activity of the enzyme. <scene name='Sandbox_37/Papain_van_der_waals/1'>Van der Waals interactions</scene> and <scene name='Sandbox_37/Papain_hydrogen_bonds/1'>hydrogen bonds</scene> between the ligands and protein maintain the structural domains of papain. Water molecules are depicted as pink spheres.Twenty-one water molecules are located in contact areas between adjacent papain molecules.

==Mechanism==

[[Image:Papain mechanism.jpg | right| thumb| Mechanism of papain catalysis]]

Papain cleaves peptide bonds of basic amino acids, leucine, or glycine. It also hydrolyzes esters and amides.<ref>http://www.sigmaaldrich.com/life-science/metabolomics/enzyme-explorer/analytical-enzymes/papain.html</ref> Its mechanism of breaking peptide bonds takes place in its <scene name='Sandbox_37/Papain_active_site/1'>active site</scene>. The active site contains a catalytic diad of residues cysteine-25 and histidine-159. The asparagine-175 residue helps with orientation during catalysis. His-159 deprotonates cys-25, then cys-25 attacks the carbonyl of the peptide as a nucleophile. A water molecule then deacylates the enzyme and releases the peptide.

~~==Structure==~~

~~<StructureSection load='9PAP' size='400' align='left' caption='Papain (9PAP)' scene=''></StructureSection>~~

Papain's three-dimensional structure is at 1.65 Angstrom resolution. It consists of one polypepetide chain that is made up of 212 amino acids residues. There are three <scene name='Sandbox_37/Papain_disulfide_bonds/1'>disulfide bonds</scene> present in the enzyme that maintains the protein's structure. Papain consists of 25% alpha helices and 21% beta sheets within its <scene name='Sandbox_37/Papain_beta-alpha/1'>secondary structure</scene>. Alpha helices are shown in red and beta sheets are shown in green. The enzyme's structure has a mixture of <scene name='Sandbox_37/Papain_hydrophobic/7'>hydrophobic residues</scene> shown in yellow and hydrophilic residues shown in purple. This corresponds to the protein's <scene name='Sandbox_37/Papain_polar/1'>polar residues</scene> shown in orange and nonpolar residues shown in green. Papain is naturally found with many <scene name='Sandbox_37/Ligand/3'>ligands</scene>. The majority are methanol molecules because the crystallization medium is 62% (w/w) methanol in water and only 29 out of 224 solvent molecules can be regarded with any certainty as methanol molecules.<ref>http://www.pdb.org/pdb/explore.do?structureId=9PAP</ref> Here, the enzyme's sulfhydryl group can also be seen which is necessary for the activity of the enzyme. <scene name='Sandbox_37/Papain_van_der_waals/1'>Van der Waals interactions</scene> and <scene name='Sandbox_37/Papain_hydrogen_bonds/1'>hydrogen bonds</scene> between the ligands and protein maintain the structural domains of papain. Water molecules are depicted as pink spheres.Twenty-one water molecules are located in contact areas between adjacent papain molecules.

==Inhibition==

<scene name='Sandbox_37/Papain_inhibitor/3'>inhibitor</scene>

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@@ Line 6: / Line 6: @@
 [[Image:Papaya.jpg | right| thumb| ''Carica papaya'']]
 <scene name='Sandbox_37/Main_scene/1'>Papain</scene> is a cysteine protease that is stable and active under a wide range of conditions. The enzyme present in the leaves, latex, roots, and fruit of the papaya plant (''Carica papaya'').<ref>http://www.britannica.com/EBchecked/topic/441803/papain</ref> The papain proteins are synthesized as inactive precursors that become active within two minutes of the plant being wounded and the latex is expelled.<ref>http://www.worthington-biochem.com/pap/default.html</ref> The latex is dried and then purified to extract the active papain enzme. The enzyme was first studied and isolated in the 1960's. It has a 23.4kDa theoretical molecular weight and works at an optimum pH of 6-7 and optimum temperature of 60-70 degrees Celsius.
+==Structure==
+<StructureSection load='9PAP' size='400' align='left' caption='Papain (9PAP)' scene=''></StructureSection>
+Papain's three-dimensional structure is at 1.65 Angstrom resolution. It consists of one polypepetide chain that is made up of 212 amino acids residues. There are three <scene name='Sandbox_37/Papain_disulfide_bonds/1'>disulfide bonds</scene> present in the enzyme that maintains the protein's structure. Papain consists of 25% alpha helices and 21% beta sheets within its <scene name='Sandbox_37/Papain_beta-alpha/1'>secondary structure</scene>. Alpha helices are shown in red and beta sheets are shown in green. The enzyme's structure has a mixture of <scene name='Sandbox_37/Papain_hydrophobic/7'>hydrophobic residues</scene> shown in yellow and hydrophilic residues shown in purple. This corresponds to the protein's <scene name='Sandbox_37/Papain_polar/1'>polar residues</scene> shown in orange and nonpolar residues shown in green. Papain is naturally found with many <scene name='Sandbox_37/Ligand/3'>ligands</scene>. The majority are methanol molecules because the crystallization medium is 62% (w/w) methanol in water and only 29 out of 224 solvent molecules can be regarded with any certainty as methanol molecules.<ref>http://www.pdb.org/pdb/explore.do?structureId=9PAP</ref> Here, the enzyme's sulfhydryl group can also be seen which is necessary for the activity of the enzyme. <scene name='Sandbox_37/Papain_van_der_waals/1'>Van der Waals interactions</scene> and <scene name='Sandbox_37/Papain_hydrogen_bonds/1'>hydrogen bonds</scene> between the ligands and protein maintain the structural domains of papain. Water molecules are depicted as pink spheres.Twenty-one water molecules are located in contact areas between adjacent papain molecules.
 ==Mechanism==
 [[Image:Papain mechanism.jpg | right| thumb| Mechanism of papain catalysis]]
 Papain cleaves peptide bonds of basic amino acids, leucine, or glycine. It also hydrolyzes esters and amides.<ref>http://www.sigmaaldrich.com/life-science/metabolomics/enzyme-explorer/analytical-enzymes/papain.html</ref> Its mechanism of breaking peptide bonds takes place in its <scene name='Sandbox_37/Papain_active_site/1'>active site</scene>. The active site contains a catalytic diad of residues cysteine-25 and histidine-159. The asparagine-175 residue helps with orientation during catalysis. His-159 deprotonates cys-25, then cys-25 attacks the carbonyl of the peptide as a nucleophile. A water molecule then deacylates the enzyme and releases the peptide.
-==Structure==
-<StructureSection load='9PAP' size='400' align='left' caption='Papain (9PAP)' scene=''></StructureSection>
-Papain's three-dimensional structure is at 1.65 Angstrom resolution. It consists of one polypepetide chain that is made up of 212 amino acids residues. There are three <scene name='Sandbox_37/Papain_disulfide_bonds/1'>disulfide bonds</scene> present in the enzyme that maintains the protein's structure. Papain consists of 25% alpha helices and 21% beta sheets within its <scene name='Sandbox_37/Papain_beta-alpha/1'>secondary structure</scene>. Alpha helices are shown in red and beta sheets are shown in green. The enzyme's structure has a mixture of <scene name='Sandbox_37/Papain_hydrophobic/7'>hydrophobic residues</scene> shown in yellow and hydrophilic residues shown in purple. This corresponds to the protein's <scene name='Sandbox_37/Papain_polar/1'>polar residues</scene> shown in orange and nonpolar residues shown in green. Papain is naturally found with many <scene name='Sandbox_37/Ligand/3'>ligands</scene>. The majority are methanol molecules because the crystallization medium is 62% (w/w) methanol in water and only 29 out of 224 solvent molecules can be regarded with any certainty as methanol molecules.<ref>http://www.pdb.org/pdb/explore.do?structureId=9PAP</ref> Here, the enzyme's sulfhydryl group can also be seen which is necessary for the activity of the enzyme. <scene name='Sandbox_37/Papain_van_der_waals/1'>Van der Waals interactions</scene> and <scene name='Sandbox_37/Papain_hydrogen_bonds/1'>hydrogen bonds</scene> between the ligands and protein maintain the structural domains of papain. Water molecules are depicted as pink spheres.Twenty-one water molecules are located in contact areas between adjacent papain molecules.
 ==Inhibition==
+<Structure load='1pop' size='500' frame='true' align='right' caption='Papain with leupeptin inhibitor (1POP)' scene='' />
 <scene name='Sandbox_37/Papain_inhibitor/3'>inhibitor</scene>