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1ht3
From Proteopedia
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 A RESOLUTION
Overview
Proteinese K (PK) isolated from Tritirachium album Limber was crystallized with HgCl2 in excess, under microgravity conditions. The intensity data were collected at 4 degrees C to 1.8 A 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 A and 2.58 A respectively from Cys-73 Sgamma. The Cys-73 in the enzyme structure is located close to the active site residue, His-69. This region is completely buried 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 belonging to the catalytic triad. As a result of this, the Ogamma of Ser-224 is displaced by 0.6 A which causes the inactivation of proteinase K by increasing the H-bond distance to 3.7 A between Ser-224 Ogamma and His-69 Nepsilon2.
About this Structure
1HT3 is a Single protein structure of sequence from Engyodontium album. Full crystallographic information is available from OCA.
Reference
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 A resolution., Gourinath S, Degenhardt M, Eschenburg S, Moore K, Delucas LJ, Betzel C, Singh TP, Indian J Biochem Biophys. 2001 Oct;38(5):298-302. PMID:11886076 Page seeded by OCA on Fri May 2 19:12:13 2008
