1ptk: Difference between revisions

Revision as of 15:32, 21 February 2008

STUDIES ON THE INHIBITORY ACTION OF MERCURY UPON PROTEINASE K

OverviewOverview

In proteinase K, Cys73 is located "below" the imidazole of the active site His69. In a 2.4-A resolution x-ray crystal structure of the complex formed between the enzyme and HgAc2, two Hg(II) positions are found: a fully occupied site, covalently bound to Cys73 (S gamma), which disrupts the catalytic triad (Asp39-His69-Ser224), and a 2-fold disordered (25 and 35% occupancy), noncovalent complexation to His72, Cys73, and Thr76 of lower affinity. The enzyme is inhibited noncompetitively at low concentrations and competitively above stoichiometric concentrations of Hg(II), but it retains 7% residual activity. This can be rationalized if the molecule is flexible enough to permit transient formation of the catalytic triad. Except for the active site, only minor structural changes are observed upon binding of Hg(II), but the thermal stability is reduced by 4 degrees C.

About this StructureAbout this Structure

1PTK is a Single protein structure of sequence from Engyodontium album with and as ligands. Active as Peptidase K, with EC number 3.4.21.64 Full crystallographic information is available from OCA.

ReferenceReference

Studies on the inhibitory action of mercury upon proteinase K., Muller A, Saenger W, J Biol Chem. 1993 Dec 15;268(35):26150-4. PMID:8253733

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-[[Image:1ptk.jpg|left|200px]]<br /><applet load="1ptk" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1ptk.jpg|left|200px]]<br /><applet load="1ptk" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1ptk, resolution 2.4&Aring;" />
 '''STUDIES ON THE INHIBITORY ACTION OF MERCURY UPON PROTEINASE K'''<br />
 ==Overview==
-In proteinase K, Cys73 is located "below" the imidazole of the active site, His69. In a 2.4-A resolution x-ray crystal structure of the complex formed, between the enzyme and HgAc2, two Hg(II) positions are found: a fully, occupied site, covalently bound to Cys73 (S gamma), which disrupts the, catalytic triad (Asp39-His69-Ser224), and a 2-fold disordered (25 and 35%, occupancy), noncovalent complexation to His72, Cys73, and Thr76 of lower, affinity. The enzyme is inhibited noncompetitively at low concentrations, and competitively above stoichiometric concentrations of Hg(II), but it, retains 7% residual activity. This can be rationalized if the molecule is, flexible enough to permit transient formation of the catalytic triad., Except for the active site, only minor structural changes are observed, upon binding of Hg(II), but the thermal stability is reduced by 4 degrees, C.
+In proteinase K, Cys73 is located "below" the imidazole of the active site His69. In a 2.4-A resolution x-ray crystal structure of the complex formed between the enzyme and HgAc2, two Hg(II) positions are found: a fully occupied site, covalently bound to Cys73 (S gamma), which disrupts the catalytic triad (Asp39-His69-Ser224), and a 2-fold disordered (25 and 35% occupancy), noncovalent complexation to His72, Cys73, and Thr76 of lower affinity. The enzyme is inhibited noncompetitively at low concentrations and competitively above stoichiometric concentrations of Hg(II), but it retains 7% residual activity. This can be rationalized if the molecule is flexible enough to permit transient formation of the catalytic triad. Except for the active site, only minor structural changes are observed upon binding of Hg(II), but the thermal stability is reduced by 4 degrees C.
 ==About this Structure==
-PTK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Engyodontium_album Engyodontium album] with HG and CA as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Peptidase_K Peptidase K], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.64 3.4.21.64] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1PTK OCA].
+PTK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Engyodontium_album Engyodontium album] with <scene name='pdbligand=HG:'>HG</scene> and <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Peptidase_K Peptidase K], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.64 3.4.21.64] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PTK OCA].
 ==Reference==
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 [[Category: hydrolase(serine proteinase)]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 00:06:56 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:32:23 2008''