1HT3

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

Summary for 1HT3

• Entry DOI: 10.2210/pdb1ht3/pdb
• Related: 1CNM 1EGQ 2PRK
• Descriptor: PROTEINASE K, MERCURY (II) ION, CALCIUM ION, ... (4 entities in total)
• Functional Keywords: proteinase k, mercury, stereochemistry, hydrolase
• Biological source: Engyodontium album
• Total number of polymer chains: 1
• Total formula weight: 29400.10

Authors

Gourinath, S. (deposition date: 2000-12-27, release date: 2001-06-27, Last modification date: 2024-10-30)

Primary citation

Gourinath, S.,Degenhardt, M.,Eschenburg, S.,Moore, K.,Delucas, L.J.,Betzel, C.H.,Singh, T.P.
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
Indian J.Biochem.Biophys., 38:298-302, 2001

PubMed Abstract: 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.

PubMed: 11886076

Experimental method

X-RAY DIFFRACTION (1.8 Å)