1ptk
|
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 HG and CA 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
Page seeded by OCA on Wed Nov 21 00:06:56 2007