Sandbox 34: Difference between revisions
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=== Introduction === | === Introduction === | ||
<Structure load='9pap' size=' | <Structure load='9pap' size='350' frame='true' align='right' caption='Papain' scene='Sandbox_34/Entire_protein_with_ligandscys/1' /> | ||
'''Papain''' is a cysteine protease, also known as '''papaya proteinase I''', from the peptidase C1 family (E.C. 3.4.22.2).<ref name="UniProt">http://www.uniprot.org/uniprot/P00784</ref> It functions as an endopeptidase, amidase, and esterase.<ref name="Worthington">http://www.worthington-biochem.com/pap/default.html</ref> Its optimal activity values for pH lie between 6.0 and 7.0, and | '''Papain''' is a cysteine protease, also known as '''papaya proteinase I''', from the peptidase C1 family (E.C. 3.4.22.2).<ref name="UniProt">http://www.uniprot.org/uniprot/P00784</ref> It functions as an endopeptidase, amidase, and esterase.<ref name="Worthington">http://www.worthington-biochem.com/pap/default.html</ref> Its optimal activity values for pH lie between 6.0 and 7.0, and its optimal temperature for activity is 65 °C. Its pI values are 8.75 and 9.55. Papain is best visualized at a wavelength of 278 nm. <ref>http://www.sigmaaldrich.com/life-science/metabolomics/enzyme-explorer/analytical-enzymes/papain.html</ref> While only consisting of a single peptide chain, papain has two domains that form a cleft in which the active site lies.<ref name="PDBSum">http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=9pap&template=clefts.html&r=speedfill</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 === | === History === | ||
Papain's enzymatic use was first discovered in 1873 by G.C. Roy who published his results in the Calcutta Medical Journal in the article, "The Solvent Action of Papaya Juice on Nitrogenous Articles of Food."<ref name="Worthington" /> In 1879, papain was named officially by Wurtz and Bouchut, who managed to partially purify the product from the sap of papaya.<ref name="Worthington" />. 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. <ref name="Worthington" /> 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.<ref name="Structure">PMID:6502713</ref> 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.<ref name="Worthington" /> | Papain's enzymatic use was first discovered in 1873 by G.C. Roy who published his results in the Calcutta Medical Journal in the article, "The Solvent Action of Papaya Juice on Nitrogenous Articles of Food."<ref name="Worthington" /> In 1879, papain was named officially by Wurtz and Bouchut, who managed to partially purify the product from the sap of papaya.<ref name="Worthington" />. 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. <ref name="Worthington" /> 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.<ref name="Structure">PMID:6502713</ref> 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.<ref name="Worthington" /> | ||
