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Mercury induced modifications in the stereochemistry of the active site through Cys-73 in a serine protease - Crystal structure of the complex of a partially modified proteinase K with mercury at 1.8 Å resolution

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Title Mercury induced modifications in the stereochemistry of the active site through Cys-73 in a serine protease - Crystal structure of the complex of a partially modified proteinase K with mercury at 1.8 Å resolution
 
Creator Gourinath, S
Degenhardt, M
Eschenburg, S
Moore, K
Delucas, L J
Betzel, Ch
Singh, T P
 
Description 298-302
Proteinese K(PK) isolated from Tritirachium album Limber was
crystallized with HgCl2 in excess. under microgravity conditions.
The intensity data were collected at 4°C to 1.8 Ǻ resolution and the final
R-factor after refinement for all the reflections was 0. 164. Mercury has been
found at two sites with partial occupancies (0.4 and 0.6) which are at distances
of 2.48 Ǻ and 2.58 Ǻ respectively from Cys-73 Sγ. The Cys-73 in the enzyme structure is
located close to the active site residue. His-69. This region is completely
buri ed and is not accessible to the solvent. It is rather tightly packed.
Therefore. the binding of mercury distorts the stereochemistry of the
neighbouring residues including those be longing to the catalytic tri ad. As a
result of this. the Oγ of Ser-224 is displaced by 0.6 Ǻ which causes the inactivation
of proteinase K by increasing the H-bond distance to 3.7 Ǻ between Ser-224 Oγ and His-69 Nε2.
 
Date 2012-12-25T18:42:59Z
2012-12-25T18:42:59Z
2001-10
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://hdl.handle.net/123456789/15317
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJBB Vol.38(5) [October 2001]