WordNet

any of a group of compounds that are inactive precursors of enzymes and require some change (such as the hydrolysis of a fragment that masks an active enzyme) to become active (同)zymogen

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/11/30 06:43:46」(JST)

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A zymogen (or proenzyme) is an inactive enzyme precursor. A zymogen requires a biochemical change (such as a hydrolysis reaction revealing the active site, or changing the configuration to reveal the active site) for it to become an active enzyme. The biochemical change usually occurs in a lysosome where a specific part of the precursor enzyme is cleaved in order to activate it. The inactivating piece which is cleaved off can be a peptide unit, or can be independently folding domains comprising more than 100 residues. Although they limit the enzyme's ability, these n-terminal extensions of the enzyme or a “prosegment” often aid in the stabilizing and folding of the enzyme they inhibit.

The pancreas secretes zymogens partly to prevent the enzymes from digesting proteins in the cells in which they are synthesised. Enzymes like pepsin are created in the form of pepsinogen, an inactive zymogen. Pepsinogen is activated when Chief cells release it into HCl which partially activates it. Another partially activated pepsinogen completes the activation by removing the peptide turning the pepsinogen into pepsin. Accidental activation of zymogens can happen when the secretion duct in the pancreas is blocked by a gallstone resulting in acute pancreatitis.

Fungi also secrete digestive enzymes into the environment as zymogens. The external environment has a different pH than inside the fungal cell and this changes the zymogen's structure into an active enzyme.

Examples[edit]

Examples of zymogens:

Angiotensinogen
Trypsinogen
Chymotrypsinogen
Pepsinogen
Most proteins in the coagulation system
Some of the proteins of the complement system
Caspases
Proelastase
Prolipase
Procarboxypolypeptidases

External links[edit]

Look up zymogen in Wiktionary, the free dictionary.

Webster entry on zymogen
Washington.edu
www.proteinscience.org:Molecular mechanisms for the conversion of zymogens to active proteolytic enzymes

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English Journal

Cloning and Expression Analysis of Genes Encoding Lytic Endopeptidases L1 and L5 from Lysobacter sp. Strain XL1.

Lapteva YS, Zolova OE, Shlyapnikov MG, Tsfasman IM, Muranova TA, Stepnaya OA, Kulaev IS, Granovsky IE.SourceLaboratory of Molecular Microbiology, G. K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
Applied and environmental microbiology.Appl Environ Microbiol.2012 Oct;78(19):7082-9. Epub 2012 Aug 3.
Lytic enzymes are the group of hydrolases that break down structural polymers of the cell walls of various microorganisms. In this work, we determined the nucleotide sequences of the Lysobacter sp. strain XL1 alpA and alpB genes, which code for, respectively, secreted lytic endopeptidases L1 (AlpA)
PMID 22865082

Effects of oxidation of lysozyme by hypohalous acids and haloamines on enzymatic activity and aggregation.

Petrônio MS, Ximenes VF.AbstractHen egg white lysozyme (HEL), an antibacterial enzyme, is a prototype protein for studying the physical and chemical events that underlie the formation of amyloid fibril aggregates. Here, we studied alterations in enzymatic activity and aggregation provoked by oxidation of HEL by hypochlorous acid (HOCl), hypobromous acid (HOBr), taurine chloramine (Tau-NHCl), taurine monobromamine (Tau-NHBr), and taurine dibromamine (Tau-NBr(2)). Addition of only 4-fold molar excess of Tau-NHBr or Tau-NBr(2) to HEL caused complete depletion of its intrinsic fluorescence, whereas HOCl and HOBr caused 40%-50% bleaching. Tau-NHCl was unable to oxidize lysozyme. The selective effect of bromamines on tryptophan residues had a direct effect on enzymatic activity; bromamines were about two-fold more effective as inhibitors of lysozyme than the acid precursors. The oxidation of HEL by HOCl and HOBr was more effective regarding the aggregation of the protein, which was evidenced by increased turbidity, Rayleigh scattering, and anisotropy. The aggregates presented spectroscopic properties that suggested the formation of amyloid fibrils, as measured by the thioflavin assay. In conclusion, the capacity of Tau-NHBr and Tau-NBr(2) as inhibitors of the bactericidal activity of HEL could represent a role in the exacerbation of pulmonary infection, since leukocytes are rich sources of both taurine and HOBr. Moreover, the oxidation of HEL by just a small excess of hypohalous acids, a condition that could be found in inflammatory sites, may represent a new pathway for initiation of aggregation.
Biochimica et biophysica acta.Biochim Biophys Acta.2012 Oct;1824(10):1090-6. Epub 2012 Jun 27.
Hen egg white lysozyme (HEL), an antibacterial enzyme, is a prototype protein for studying the physical and chemical events that underlie the formation of amyloid fibril aggregates. Here, we studied alterations in enzymatic activity and aggregation provoked by oxidation of HEL by hypochlorous acid (
PMID 22750692

PPP2R1A mutations are common in the serous type of endometrial cancer.

Nagendra DC, Burke J 3rd, Maxwell GL, Risinger JI.SourceDepartment of Obstetrics, Gynecology and Reproductive Biology, Michigan State University College of Human Medicine, Grand Rapids, Michigan.
Molecular carcinogenesis.Mol Carcinog.2012 Oct;51(10):826-31. doi: 10.1002/mc.20850. Epub 2011 Aug 31.
Recently unbiased sequencing efforts identified PPP2R1A mutations in clear cell ovarian cancers (OCC). Similar mutations were also noted with high frequency in uterine serous carcinoma. Because the endometrium develops from the same developmental precursors we further examined the hypothesis that PP
PMID 21882256

Japanese Journal

Propeptide processing and proteolytic activity of proenzymes of the Staphylococcal and Enterococcal GluV8-family protease

Rouf S M A,Ohara-Nemoto Yuko,Shimoyama Y,Kimura S,Ono Toshio,Nemoto Takayuki K.
Indian Journal of Biochemistry and Biophysics 49(6), 421-427, 2012-12-00
… In addition, proteolytic activity of proenzyme of GluV8 carrying Arg-3AlaAsn-1 is demonstrated with synthetic peptide substrates LLE/Q-MCA. …
NAID 120005196714

Elucidation of Crucial Structures for a Catechol-Based Inhibitor of Plasma Hyaluronan-Binding Protein (Factor VII Activating Protease) Autoactivation

YAMAMOTO Eisaku,KITANO Yoshikazu,HASUMI Keiji
Bioscience, biotechnology, and biochemistry 75(10), 2070-2072, 2011-10-23
… Previous investigations have suggested the presence of catechol-binding sites in its proenzyme form, pro-PHBP. …
NAID 10029873414

Inhibition of Plasma Hyaluronan-Binding Protein Autoactivation by Laccaic Acid

Sekido Chikako,Nishimura Naoko,Takai Masayuki [他],HASUMI Keiji
Bioscience, biotechnology, and biochemistry 74(11), 2320-2322, 2010-11-23
… We identified laccaic acid, a widely used food coloring from scale insects, as a potent inhibitor of the protease in terms of both autoactivation of the PHBP proenzyme (IC<SUB>50</SUB> …
NAID 10027561853

Imaging and Targeting of the Hypoxia-inducible Factor 1-active Microenvironment

Kizaka-Kondoh Shinae,Tanaka Shotaro,Hiraoka Masahiro
Journal of toxicologic pathology 22(2), 93-100, 2009-06-01
… The drug consists of the following three functional domains: the protein transduction domain (PTD), which efficiently delivers the fusion protein to hypoxic tumor cells, the ODD domain, which has a VHL-mediated protein destruction motif of human HIF-1α protein and confers hypoxia-dependent stabilization to the fusion proteins, and the human procaspase-3 proenzyme responsible for the cytocidal activity of the protein drug. …
NAID 10030977756