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'''Papain''' is a [[cysteine protease]], also known as '''papaya proteinase I''',from the peptidase C1 family with E.C. 3.4.22.2.It functions as a hydrolase, endopeptidase, and thiol protease.<ref name="UniProt">http://www.uniprot.org/uniprot/P00784</ref> Naturally found in the latex of the papaya fruit, one of the most common uses of papain is as a meat tenderizer because of its ability to hydrolyze esters and amides.<ref>IUBMB Enzyme Nomenclature: www.chem.qmul.ac.uk/iubmb/enzyme/EC3/4/22/2.html</ref> Another common use is as a digestive aid. Papaya is commonly referenced as a preferred fruit for those suffering from gastroesophageal reflux disease due to its ability to help the the stomach with digestion of complex proteins.

'''Papain''' is a [[cysteine protease]], also known as '''papaya proteinase I''', from the peptidase C1 family with E.C. 3.4.22.2. It functions as a hydrolase, endopeptidase, and thiol protease.<ref name="UniProt">http://www.uniprot.org/uniprot/P00784</ref> Naturally found in the latex of the papaya fruit, one of the most common uses of papain is as a meat tenderizer because of its ability to hydrolyze esters and amides.<ref>IUBMB Enzyme Nomenclature: www.chem.qmul.ac.uk/iubmb/enzyme/EC3/4/22/2.html</ref> Another common use is as a digestive aid. Papaya is commonly referenced as a preferred fruit for those suffering from gastroesophageal reflux disease due to its ability to help the the stomach with digestion of complex proteins.

Papain digests a large variety of proteins, with a very broad specificity. Its <scene name='Sandbox_34/9pap_active_site/1'>active site</scene>consists of the residues cysteine-25, histidine-159, and asparagine-175. It cleaves the peptide bonds of basic amino acids, leucine and glycine by nucleophilic attack with its sulfhydryl group on cysteine-25 <ref>http://www.ebi.ac.uk/QuickGO/GTerm?id=GO:0004197</ref>. It also hydrolyzes esters and amides. It prefers amino acids that bear large hydrophobic side chains at the P2 position, and will not accept valine at the P1' position. <ref name"UniProt" />

~~</StructureSection~~>

<StructureSection load='9pap' size='500' side='right' caption='Structure of 9PAP (PDB entry [[9pap]])'

== External References ==

[http://en.wikipedia.org/wiki/Papain Wikipedia]

Papain is a cysteine protease, also known as papaya proteinase I, from the peptidase C1 family with E.C. 3.4.22.2. It functions as a hydrolase, endopeptidase, and thiol protease.^[1] Naturally found in the latex of the papaya fruit, one of the most common uses of papain is as a meat tenderizer because of its ability to hydrolyze esters and amides.^[2] Another common use is as a digestive aid. Papaya is commonly referenced as a preferred fruit for those suffering from gastroesophageal reflux disease due to its ability to help the the stomach with digestion of complex proteins.

History

Papain's enzymatic use was first discovered in 1873 by G.C. Roy. Roy published his results in the Calcutta Medical Journal in the article, "The Solvent Action of Papaya Juice on Nitrogenous Articles of Food."^[3] In 1879, papain was named officially by Wurtz and Bouchut, who managed to partially purify the product from the sap of papaya.^[3]. It wasn't until the mid-twentieth century that the complete purification and isolation of papain was achieved. In 1968, Drenth et al. determined the structure of papain by x-ray crystallography, making it the second enzyme whose structure was successfully determined by x-ray crystallography. Additionally, papain was the first cysteine protease to have its structure identified. ^[3] In 1984, Kamphuis et al. determined the geometry of the active site, and the three-dimensional structure was visualized to a 1.65 Angstrom solution.^[4] Today, studies continue on the stability of papain, involving changes in environmental conditions, in addition to testing of inhibitors such as phenylmethanesulfonylfluoride (PMSF), TLCK, TPCK, aplh2-macroglobulin, heavy metals, AEBSF, antipain, cystatin, E-64, leupeptin, sulfhydryl binding agents, carbonyl reagents, and alkylating agents.^[3]

Papain is a relatively simple enzyme. It consists of only one chain of 212 residues with three disulfide bonds, illustrated in yellow.^[4] A modified cysteine residue with a sulhydryl group, , is necessary for the activity of the enzyme.^[5] In 9PAP, the sulfhydryl group has been oxidized. Papain contains many illustrated in magenta.

1 Ligands
2 Specificity
3 Inhibitors
4 References
5 External References

Ligands

Papain binds many methanol molecules via hydrogen bonding.

Specificity

Papain digests a large variety of proteins, with a very broad specificity. Its consists of the residues cysteine-25, histidine-159, and asparagine-175. It cleaves the peptide bonds of basic amino acids, leucine and glycine by nucleophilic attack with its sulfhydryl group on cysteine-25 ^[6]. It also hydrolyzes esters and amides. It prefers amino acids that bear large hydrophobic side chains at the P2 position, and will not accept valine at the P1' position. ^[1]

Inhibitors

References

↑ ^1.0 ^1.1 http://www.uniprot.org/uniprot/P00784
↑ IUBMB Enzyme Nomenclature: www.chem.qmul.ac.uk/iubmb/enzyme/EC3/4/22/2.html
↑ ^3.0 ^3.1 ^3.2 ^3.3 http://www.worthington-biochem.com/pap/default.html
↑ ^4.0 ^4.1 Kamphuis IG, Kalk KH, Swarte MB, Drenth J. Structure of papain refined at 1.65 A resolution. J Mol Biol. 1984 Oct 25;179(2):233-56. PMID:6502713
↑ http://www.sigmaaldrich.com/life-science/metabolomics/enzyme-explorer/analytical-enzymes/papain.html
↑ http://www.ebi.ac.uk/QuickGO/GTerm?id=GO:0004197

External References

Wikipedia

@@ Line 9: / Line 9: @@
 <StructureSection load='9pap' size='500' side='right' caption='Structure of 9PAP (PDB entry [[9pap]])' scene='Sandbox_34/9pap_without_solvent_meoh/3'>
-'''Papain''' is a [[cysteine protease]], also known as '''papaya proteinase I''',from the peptidase C1 family with E.C. 3.4.22.2.It functions as a hydrolase, endopeptidase, and thiol protease.<ref name="UniProt">http://www.uniprot.org/uniprot/P00784</ref> Naturally found in the latex of the papaya fruit, one of the most common uses of papain is as a meat tenderizer because of its ability to hydrolyze esters and amides.<ref>IUBMB Enzyme Nomenclature: www.chem.qmul.ac.uk/iubmb/enzyme/EC3/4/22/2.html</ref> Another common use is as a digestive aid. Papaya is commonly referenced as a preferred fruit for those suffering from gastroesophageal reflux disease due to its ability to help the the stomach with digestion of complex proteins.
+'''Papain''' is a [[cysteine protease]], also known as '''papaya proteinase I''', from the peptidase C1 family with E.C. 3.4.22.2. It functions as a hydrolase, endopeptidase, and thiol protease.<ref name="UniProt">http://www.uniprot.org/uniprot/P00784</ref> Naturally found in the latex of the papaya fruit, one of the most common uses of papain is as a meat tenderizer because of its ability to hydrolyze esters and amides.<ref>IUBMB Enzyme Nomenclature: www.chem.qmul.ac.uk/iubmb/enzyme/EC3/4/22/2.html</ref> Another common use is as a digestive aid. Papaya is commonly referenced as a preferred fruit for those suffering from gastroesophageal reflux disease due to its ability to help the the stomach with digestion of complex proteins.
 == History ==
@@ Line 30: / Line 30: @@
 == Specificity ==
-Papain digests a large variety of proteins, with a very broad specificity. Its <scene name='Sandbox_34/9pap_active_site/1'>active site</scene>consists of the residues cysteine-25, histidine-159, and asparagine-175. It cleaves the peptide bonds of basic amino acids, leucine and glycine by nucleophilic attack with its sulfhydryl group on cysteine-25 <ref>http://www.ebi.ac.uk/QuickGO/GTerm?id=GO:0004197</ref>. It also hydrolyzes esters and amides. It prefers amino acids that bear large hydrophobic side chains at the P2 position, and will not accept valine at the P1' position. <ref name"UniProt" />
+Papain digests a large variety of proteins, with a very broad specificity. Its <scene name='Sandbox_34/9pap_active_site/1'>active site</scene>consists of the residues cysteine-25, histidine-159, and asparagine-175. It cleaves the peptide bonds of basic amino acids, leucine and glycine by nucleophilic attack with its sulfhydryl group on cysteine-25 <ref>http://www.ebi.ac.uk/QuickGO/GTerm?id=GO:0004197</ref>. It also hydrolyzes esters and amides. It prefers amino acids that bear large hydrophobic side chains at the P2 position, and will not accept valine at the P1' position. <ref name="UniProt" />
-</StructureSection>
 == Inhibitors ==
-<StructureSection load='9pap' size='500' side='right' caption='Structure of 9PAP (PDB entry [[9pap]])'
-</StructureSection>
 == References ==
 <references />
+== External References ==
+[http://en.wikipedia.org/wiki/Papain Wikipedia]

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Revision as of 22:51, 13 November 2011

Papain

Introduction

History

Structure

Contents

Ligands

Specificity

Inhibitors

References

External References

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